Title 29: Labor
PART 1910—OCCUPATIONAL SAFETY AND HEALTH STANDARDS
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Subpart D—Walking-Working Surfaces
Authority: Secs. 4, 6, and 8 of the Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655, and 657); Secretary of Labor's Order No. 12–71 (36 FR 8754), 8–76 (41 FR 25059), 9–83 (48 FR 35736), or 1–90 (55 FR 9033), as applicable; and 29 CFR part 1911.
§ 1910.21 Definitions.
(a) As used in §1910.23, unless the context requires otherwise, floor and wall opening, railing and toe board terms shall have the meanings ascribed in this paragraph.
(1) Floor hole. An opening measuring less than 12 inches but more than 1 inch in its least dimension, in any floor, platform, pavement, or yard, through which materials but not persons may fall; such as a belt hole, pipe opening, or slot opening.
(2) Floor opening. An opening measuring 12 inches or more in its least dimension, in any floor, platform, pavement, or yard through which persons may fall; such as a hatchway, stair or ladder opening, pit, or large manhole. Floor openings occupied by elevators, dumb waiters, conveyors, machinery, or containers are excluded from this subpart.
(3) Handrail. A single bar or pipe supported on brackets from a wall or partition, as on a stairway or ramp, to furnish persons with a handhold in case of tripping.
(4) Platform. A working space for persons, elevated above the surrounding floor or ground; such as a balcony or platform for the operation of machinery and equipment.
(5) Runway. A passageway for persons, elevated above the surrounding floor or ground level, such as a footwalk along shafting or a walkway between buildings.
(6) Standard railing. A vertical barrier erected along exposed edges of a floor opening, wall opening, ramp, platform, or runway to prevent falls of persons.
(7) Standard strength and construction. Any construction of railings, covers, or other guards that meets the requirements of §1910.23.
(8) Stair railing. A vertical barrier erected along exposed sides of a stairway to prevent falls of persons.
(9) Toeboard. A vertical barrier at floor level erected along exposed edges of a floor opening, wall opening, platform, runway, or ramp to prevent falls of materials.
(10) Wall hole. An opening less than 30 inches but more than 1 inch high, of unrestricted width, in any wall or partition; such as a ventilation hole or drainage scupper.
(11) Wall opening. An opening at least 30 inches high and 18 inches wide, in any wall or partition, through which persons may fall; such as a yard-arm doorway or chute opening.
(b) As used in §1910.24, unless the context requires otherwise, fixed industrial stair terms shall have the meaning ascribed in this paragraph.
(1) Handrail. A single bar or pipe supported on brackets from a wall or partition to provide a continuous handhold for persons using a stair.
(2) Nose, nosing. That portion of a tread projecting beyond the face of the riser immediately below.
(3) Open riser. The air space between the treads of stairways without upright members (risers).
(4) Platform. An extended step or landing breaking a continuous run of stairs.
(5) Railing. A vertical barrier erected along exposed sides of stairways and platforms to prevent falls of persons. The top member of railing usually serves as a handrail.
(6) Rise. The vertical distance from the top of a tread to the top of the next higher tread.
(7) Riser. The upright member of a step situated at the back of a lower tread and near the leading edge of the next higher tread.
(8) Stairs, stairway. A series of steps leading from one level or floor to another, or leading to platforms, pits, boiler rooms, crossovers, or around machinery, tanks, and other equipment that are used more or less continuously or routinely by employees, or only occasionally by specific individuals. A series of steps and landings having three or more risers constitutes stairs or stairway.
(9) Tread. The horizontal member of a step.
(10) Tread run. The horizontal distance from the leading edge of a tread to the leading edge of an adjacent tread.
(11) Tread width. The horizontal distance from front to back of tread including nosing when used.
(c) As used in §1910.25, unless the context requires otherwise, portable wood ladders terms shall have the meanings ascribed in this paragraph.
(1) Ladders. A ladder is an appliance usually consisting of two side rails joined at regular intervals by cross- pieces called steps, rungs, or cleats, on which a person may step in ascending or descending.
(2) Stepladder. A stepladder is a selfsupporting portable ladder, nonadjustable in length, having flat steps and a hinged back. Its size is designated by the overall length of the ladder measured along the front edge of the side rails.
(3) Single ladder. A single ladder is a non-self-supporting portable ladder, nonadjustable in length, consisting of but one section. Its size is designated by the overall length of the side rail.
(4) Extension ladder. An extension ladder is a non-self-supporting portable ladder adjustable in length. It consists of two or more sections traveling in guides or brackets so arranged as to permit length adjustment. Its size is designated by the sum of the lengths of the sections measured along the side rails.
(5) Sectional ladder. A sectional ladder is a non-self-supporting portable ladder, nonadjustable in length, consisting of two or more sections of ladder so constructed that the sections may be combined to function as a single ladder. Its size is designated by the overall length of the assembled sections.
(6) Trestle ladder. A trestle ladder is a self-supporting portable ladder, nonadjustable in length, consisting of two sections hinged at the top to form equal angles with the base. The size is designated by the length of the side rails measured along the front edge.
(7) Extension trestle ladder. An extension trestle ladder is a self-supporting portable ladder, adjustable in length, consisting of a trestle ladder base and a vertically adjustable single ladder, with suitable means for locking the ladders together. The size is designated by the length of the trestle ladder base.
(8) Special-purpose ladder. A special-purpose ladder is a portable ladder which represents either a modification or a combination of design or construction features in one of the general-purpose types of ladders previously defined, in order to adapt the ladder to special or specific uses.
(9) Trolley ladder. A trolley ladder is a semifixed ladder, nonadjustable in length, supported by attachments to an overhead track, the plane of the ladder being at right angles to the plane of motion.
(10) Side-rolling ladder. A side-rolling ladder is a semifixed ladder, nonadjustable in length, supported by attachments to a guide rail, which is generally fastened to shelving, the plane of the ladder being also its plane of motion.
(11) Wood characteristics. Wood characteristics are distinguishing features which by their extent and number determine the quality of a piece of wood.
(12) Wood irregularities. Wood irregularities are natural characteristics in or on wood that may lower its durability, strength, or utility.
(13) Cross grain. Cross grain (slope of grain) is a deviation of the fiber direction from a line parallel to the sides of the piece.
(14) Knot. A knot is a branch or limb, imbedded in the tree and cut through in the process of lumber manufacture, classified according to size, quality, and occurrence. The size of the knot is determined as the average diameter on the surface of the piece.
(15) Pitch and bark pockets. A pitch pocket is an opening extending parallel to the annual growth rings containing, or that has contained, pitch, either solid or liquid. A bark pocket is an opening between annual growth rings that contains bark.
(16) Shake. A shake is a separation along the grain, most of which occurs between the rings of annual growth.
(17) Check. A check is a lengthwise separation of the wood, most of which occurs across the rings of annual growth.
(18) Wane. Wane is bark, or the lack of wood from any cause, on the corner of a piece.
(19) Decay. Decay is disintegration of wood substance due to action of wood-destroying fungi. It is also known as dote and rot.
(20) Compression failure. A compression failure is a deformation (buckling) of the fibers due to excessive compression along the grain.
(21) Compression wood. Compression wood is an aberrant (abnormal) and highly variable type of wood structure occurring in softwood species. The wood commonly has density somewhat higher than does normal wood, but somewhat lower stiffness and tensile strength for its weight in addition to high longitudinal shrinkage.
(22) Low density. Low-density wood is that which is exceptionally light in weight and usually deficient in strength properties for the species.
(d) As used in §1910.26, unless the context requires otherwise, portable metal ladder terms shall have the meanings ascribed in this paragraph.
(1) Ladder. A ladder is an appliance usually consisting of two side rails joined at regular intervals by cross- pieces called steps, rungs, or cleats, on which a person may step in ascending or descending.
(2) Step ladder. A step ladder is a self-supporting portable ladder, nonadjustable in length, having flat steps and a hinged back. Its size is designated by the overall length of the ladder measured along the front edge of the side rails.
(3) Single ladder. A single ladder is a non-self-supporting portable ladder, nonadjustable in length, consisting of but one section. Its size is designated by the overall length of the side rail.
(4) Extension ladder. An extension ladder is a non-self-supporting portable ladder adjustable in length. It consists of two or more sections traveling in guides or brackets so arranged as to permit length adjustment. Its size is designated by the sum of the lengths of the sections measured along the side rails.
(5) Platform ladder. A self-supporting ladder of fixed size with a platform provided at the working level. The size is determined by the distance along the front rail from the platform to the base of the ladder.
(6) Sectional ladder. A sectional ladder is a non-self-supporting portable ladder, non-adjustable in length, consisting of two or more sections so constructed that the sections may be combined to function as a single ladder. Its size is designated by the overall length of the assembled sections.
(7) Trestle ladder. A trestle ladder is a self-supporting portable ladder, non-adjustable in length, consisting of two sections, hinged at the top to form equal angles with the base. The size is designated by the length of the side rails measured along the front edge.
(8) Extension trestle ladder. An extension trestle ladder is a self-supporting portable ladder, adjustable in length, consisting of a trestle ladder base and a vertically adjustable single ladder, with suitable means for locking the ladders together. The size is designated by the length of the trestle ladder base.
(9) Special-purpose ladder. A special-purpose ladder is a portable ladder which represents either a modification or a combination of design or construction features in one of the general-purpose types of ladders previously defined, in order to adapt the ladder to special or specific uses.
(e) As used in §1910.27, unless the context requires otherwise, fixed ladder terms shall have the meanings ascribed in this paragraph.
(1) Ladder. A ladder is an appliance usually consisting of two side rails joined at regular intervals by cross- pieces called steps, rungs, or cleats, on which a person may step in ascending or descending.
(2) Fixed ladder. A fixed ladder is a ladder permanently attached to a structure, building, or equipment.
(3) Individual-rung ladder. An individual-rung ladder is a fixed ladder each rung of which is individually attached to a structure, building, or equipment.
(4) Rail ladder. A rail ladder is a fixed ladder consisting of side rails joined at regular intervals by rungs or cleats and fastened in full length or in sections to a building, structure, or equipment.
(5) Railings. A railing is any one or a combination of those railings constructed in accordance with §1910.23. A standard railing is a vertical barrier erected along exposed edges of floor openings, wall openings, ramps, platforms, and runways to prevent falls of persons.
(6) Pitch. Pitch is the included angle between the horizontal and the ladder, measured on the opposite side of the ladder from the climbing side.
(7) Fastenings. A fastening is a device to attach a ladder to a structure, building, or equipment.
(8) Rungs. Rungs are ladder cross- pieces of circular or oval cross-section on which a person may step in ascending or descending.
(9) Cleats. Cleats are ladder cross- pieces of rectangular cross-section placed on edge on which a person may step in ascending or descending.
(10) Steps. Steps are the flat cross- pieces of a ladder on which a person may step in ascending or descending.
(11) Cage. A cage is a guard that may be referred to as a cage or basket guard which is an enclosure that is fastened to the side rails of the fixed ladder or to the structure to encircle the climbing space of the ladder for the safety of the person who must climb the ladder.
(12) Well. A well is a permanent complete enclosure around a fixed ladder, which is attached to the walls of the well. Proper clearances for a well will give the person who must climb the ladder the same protection as a cage.
(13) Ladder safety device. A ladder safety device is any device, other than a cage or well, designed to eliminate or reduce the possibility of accidental falls and which may incorporate such features as life belts, friction brakes, and sliding attachments.
(14) Grab bars. Grab bars are individual handholds placed adjacent to or as an extension above ladders for the purpose of providing access beyond the limits of the ladder.
(15) Through ladder. A through ladder is one from which a man getting off at the top must step through the ladder in order to reach the landing.
(16) Side-step ladder. A side-step ladder is one from which a man getting off at the top must step sideways from the ladder in order to reach the landing.
(f) As used in §1910.28, unless the context requires otherwise, scaffolding terms shall have the meaning ascribed in this paragraph.
(1) Bearer. A horizontal member of a scaffold upon which the platform rests and which may be supported by ledgers.
(2) Boatswain's chair. A seat supported by slings attached to a suspended rope, designed to accommodate one workman in a sitting position.
(3) Brace. A tie that holds one scaffold member in a fixed position with respect to another member.
(4) Bricklayers' square scaffold. A scaffold composed of framed wood squares which support a platform limited to light and medium duty.
(5) Carpenters' bracket scaffold. A scaffold consisting of wood or metal brackets supporting a platform.
(6) Coupler. A device for locking together the component parts of a tubular metal scaffold. The material used for the couplers shall be of a structural type, such as a drop-forged steel, malleable iron, or structural grade aluminum. The use of gray cast iron is prohibited.
(7) Crawling board or chicken ladder. A plank with cleats spaced and secured at equal intervals, for use by a worker on roofs, not designed to carry any material.
(8) Double pole or independent pole scaffold. A scaffold supported from the base by a double row of uprights, independent of support from the walls and constructed of uprights, ledgers, horizontal platform bearers, and diagonal bracing.
(9) Float or ship scaffold. A scaffold hung from overhead supports by means of ropes and consisting of a substantial platform having diagonal bracing underneath, resting upon and securely fastened to two parallel plank bearers at right angles to the span.
(10) Guardrail. A rail secured to uprights and erected along the exposed sides and ends of platforms.
(11) Heavy duty scaffold. A scaffold designed and constructed to carry a working load not to exceed 75 pounds per square foot.
(12) Horse scaffold. A scaffold for light or medium duty, composed of horses supporting a work platform.
(13) Interior hung scaffold. A scaffold suspended from the ceiling or roof structure.
(14) Ladder jack scaffold. A light duty scaffold supported by brackets attached to ladders.
(15) Ledger (stringer). A horizontal scaffold member which extends from post to post and which supports the putlogs or bearer forming a tie between the posts.
(16) Light duty scaffold. A scaffold designed and constructed to carry a working load not to exceed 25 pounds per square foot.
(17) Manually propelled mobile scaffold. A portable rolling scaffold supported by casters.
(18) Masons' adjustable multiple-point suspension scaffold. A scaffold having a continuous platform supported by bearers suspended by wire rope from overhead supports, so arranged and operated as to permit the raising or lowering of the platform to desired working positions.
(19) Maximum intended load. The total of all loads including the working load, the weight of the scaffold, and such other loads as may be reasonably anticipated.
(20) Medium duty scaffold. A scaffold designed and constructed to carry a working load not to exceed 50 pounds per square foot.
(21) Mid-rail. A rail approximately midway between the guardrail and platform, used when required, and secured to the uprights erected along the exposed sides and ends of platforms.
(22) Needle beam scaffold. A light duty scaffold consisting of needle beams supporting a platform.
(23) Outrigger scaffold. A scaffold supported by outriggers or thrustouts projecting beyond the wall or face of the building or structure, the inboard ends of which are secured inside of such a building or structure.
(24) Putlog. A scaffold member upon which the platform rests.
(25) Roofing bracket. A bracket used in sloped roof construction, having provisions for fastening to the roof or supported by ropes fastened over the ridge and secured to some suitable object.
(26) Runner. The lengthwise horizontal bracing or bearing members or both.
(27) Scaffold. Any temporary elevated platform and its supporting structure used for supporting workmen or materials or both.
(28) Single-point adjustable suspension scaffold. A manually or power-operated unit designed for light duty use, supported by a single wire rope from an overhead support so arranged and operated as to permit the raising or lowering of the platform to desired working positions.
(29) Single pole scaffold. Platforms resting on putlogs or crossbeams, the outside ends of which are supported on ledgers secured to a single row of posts or uprights and the inner ends of which are supported on or in a wall.
(30) Stone setters' adjustable multiple-point suspension scaffold. A swinging-type scaffold having a platform supported by hangers suspended at four points so as to permit the raising or lowering of the platform to the desired working position by the use of hoisting machines.
(31) Toeboard. A barrier secured along the sides and ends of a platform, to guard against the falling of material.
(32) Tube and coupler scaffold. An assembly consisting of tubing which serves as posts, bearers, braces, ties, and runners, a base supporting the posts, and special couplers which serve to connect the uprights and to join the various members.
(33) Tubular welded frame scaffold. A sectional, panel, or frame metal scaffold substantially built up of prefabricated welded sections which consist of posts and horizontal bearer with intermediate members. Panels or frames shall be braced with diagonal or cross braces.
(34) Two-point suspension scaffold (swinging scaffold). A scaffold, the platform of which is supported by hangers (stirrups) at two points, suspended from overhead supports so as to permit the raising or lowering of the platform to the desired working position by tackle or hoisting machines.
(35) Window jack scaffold. A scaffold, the platform of which is supported by a bracket or jack which projects through a window opening.
(36) Working load. Load imposed by men, materials, and equipment.
(g) As used in §1910.29, unless the context requires otherwise, manually propelled mobile ladder stand and scaffold (tower) terms shall have the meaning ascribed in this paragraph.
(1) Bearer. A horizontal member of a scaffold upon which the platform rests and which may be supported by ledgers.
(2) Brace. A tie that holds one scaffold member in a fixed position with respect to another member.
(3) Climbing ladder. A separate ladder with equally spaced rungs usually attached to the scaffold structure for climbing and descending.
(4) Coupler. A device for locking together the components of a tubular metal scaffold which shall be designed and used to safely support the maximum intended loads.
(5) Design working load. The maximum intended load, being the total of all loads including the weight of the men, materials, equipment, and platform.
(6) Equivalent. Alternative design or features, which will provide an equal degree or factor of safety.
(7) Guardrail. A barrier secured to uprights and erected along the exposed sides and ends of platforms to prevent falls of persons.
(8) Handrail. A rail connected to a ladder stand running parallel to the slope and/or top step.
(9) Ladder stand. A mobile fixed size self-supporting ladder consisting of a wide flat tread ladder in the form of stairs. The assembly may include handrails.
(10) Ledger (stringer). A horizontal scaffold member which extends from post to post and which supports the bearer forming a tie between the posts.
(11) Mobile scaffold (tower). A light, medium, or heavy duty scaffold mounted on casters or wheels.
(12) Mobile. “Manually propelled.”
(13) Mobile work platform. Generally a fixed work level one frame high on casters or wheels, with bracing diagonally from platform to vertical frame.
(14) Runner. The lengthwise horizontal bracing and/or bearing members.
(15) Scaffold. Any temporary elevated platform and its necessary vertical, diagonal, and horizontal members used for supporting workmen and materials. (Also known as a scaffold tower.)
(16) Toeboard. A barrier at platform level erected along the exposed sides and ends of a scaffold platform to prevent falls of materials.
(17) Tube and coupler scaffold. An assembly consisting of tubing which serves as posts, bearers, braces, ties, and runners, a base supporting the posts, and uprights, and serves to join the various members, usually used in fixed locations.
(18) Tubular welded frame scaffold. A sectional, panel, or frame metal scaffold substantially built up of prefabricated welded sections, which consist of posts and bearers with intermediate connecting members and braced with diagonal or cross braces.
(19) Tubular welded sectional folding scaffold. A sectional, folding metal scaffold either of ladder frame or inside stairway design, substantially built of prefabricated welded sections, which consist of end frames, platform frame, inside inclined stairway frame and braces, or hinged connected diagonal and horizontal braces, capable of being folded into a flat package when the scaffold is not in use.
(20) Work level. The elevated platform, used for supporting workmen and their materials, comprising the necessary vertical, horizontal, and diagonal braces, guardrails, and ladder for access to the work platform.
§ 1910.22 General requirements.
This section applies to all permanent places of employment, except where domestic, mining, or agricultural work only is performed. Measures for the control of toxic materials are considered to be outside the scope of this section.
(a) Housekeeping. (1) All places of employment, passageways, storerooms, and service rooms shall be kept clean and orderly and in a sanitary condition.
(2) The floor of every workroom shall be maintained in a clean and, so far as possible, a dry condition. Where wet processes are used, drainage shall be maintained, and false floors, platforms, mats, or other dry standing places should be provided where practicable.
(3) To facilitate cleaning, every floor, working place, and passageway shall be kept free from protruding nails, splinters, holes, or loose boards.
(b) Aisles and passageways. (1) Where mechanical handling equipment is used, sufficient safe clearances shall be allowed for aisles, at loading docks, through doorways and wherever turns or passage must be made. Aisles and passageways shall be kept clear and in good repairs, with no obstruction across or in aisles that could create a hazard.
(2) Permanent aisles and passageways shall be appropriately marked.
(c) Covers and guardrails. Covers and/or guardrails shall be provided to protect personnel from the hazards of open pits, tanks, vats, ditches, etc.
(d) Floor loading protection. (1) In every building or other structure, or part thereof, used for mercantile, business, industrial, or storage purposes, the loads approved by the building official shall be marked on plates of approved design which shall be supplied and securely affixed by the owner of the building, or his duly authorized agent, in a conspicuous place in each space to which they relate. Such plates shall not be removed or defaced but, if lost, removed, or defaced, shall be replaced by the owner or his agent.
(2) It shall be unlawful to place, or cause, or permit to be placed, on any floor or roof of a building or other structure a load greater than that for which such floor or roof is approved by the building official.
§ 1910.23 Guarding floor and wall openings and holes.
(a) Protection for floor openings. (1) Every stairway floor opening shall be guarded by a standard railing constructed in accordance with paragraph (e) of this section. The railing shall be provided on all exposed sides (except at entrance to stairway). For infrequently used stairways where traffic across the opening prevents the use of fixed standard railing (as when located in aisle spaces, etc.), the guard shall consist of a hinged floor opening cover of standard strength and construction and removable standard railings on all exposed sides (except at entrance to stairway).
(2) Every ladderway floor opening or platform shall be guarded by a standard railing with standard toeboard on all exposed sides (except at entrance to opening), with the passage through the railing either provided with a swinging gate or so offset that a person cannot walk directly into the opening.
(3) Every hatchway and chute floor opening shall be guarded by one of the following:
(i) Hinged floor opening cover of standard strength and construction equipped with standard railings or permanently attached thereto so as to leave only one exposed side. When the opening is not in use, the cover shall be closed or the exposed side shall be guarded at both top and intermediate positions by removable standard railings.
(ii) A removable railing with toeboard on not more than two sides of the opening and fixed standard railings with toeboards on all other exposed sides. The removable railings shall be kept in place when the opening is not in use.
Where operating conditions necessitate the feeding of material into any hatchway or chute opening, protection shall be provided to prevent a person from falling through the opening.
(4) Every skylight floor opening and hole shall be guarded by a standard skylight screen or a fixed standard railing on all exposed sides.
(5) Every pit and trapdoor floor opening, infrequently used, shall be guarded by a floor opening cover of standard strength and construction. While the cover is not in place, the pit or trap opening shall be constantly attended by someone or shall be protected on all exposed sides by removable standard railings.
(6) Every manhole floor opening shall be guarded by a standard manhole cover which need not be hinged in place. While the cover is not in place, the manhole opening shall be constantly attended by someone or shall be protected by removable standard railings.
(7) Every temporary floor opening shall have standard railings, or shall be constantly attended by someone.
(8) Every floor hole into which persons can accidentally walk shall be guarded by either:
(i) A standard railing with standard toeboard on all exposed sides, or
(ii) A floor hole cover of standard strength and construction. While the cover is not in place, the floor hole shall be constantly attended by someone or shall be protected by a removable standard railing.
(9) Every floor hole into which persons cannot accidentally walk (on account of fixed machinery, equipment, or walls) shall be protected by a cover that leaves no openings more than 1 inch wide. The cover shall be securely held in place to prevent tools or materials from falling through.
(10) Where doors or gates open directly on a stairway, a platform shall be provided, and the swing of the door shall not reduce the effective width to less than 20 inches.
(b) Protection for wall openings and holes. (1) Every wall opening from which there is a drop of more than 4 feet shall be guarded by one of the following:
(i) Rail, roller, picket fence, half door, or equivalent barrier. Where there is exposure below to falling materials, a removable toe board or the equivalent shall also be provided. When the opening is not in use for handling materials, the guard shall be kept in position regardless of a door on the opening. In addition, a grab handle shall be provided on each side of the opening with its center approximately 4 feet above floor level and of standard strength and mounting.
(ii) Extension platform onto which materials can be hoisted for handling, and which shall have side rails or equivalent guards of standard specifications.
(2) Every chute wall opening from which there is a drop of more than 4 feet shall be guarded by one or more of the barriers specified in paragraph (b)(1) of this section or as required by the conditions.
(3) Every window wall opening at a stairway landing, floor, platform, or balcony, from which there is a drop of more than 4 feet, and where the bottom of the opening is less than 3 feet above the platform or landing, shall be guarded by standard slats, standard grill work (as specified in paragraph (e)(11) of this section), or standard railing.
Where the window opening is below the landing, or platform, a standard toe board shall be provided.
(4) Every temporary wall opening shall have adequate guards but these need not be of standard construction.
(5) Where there is a hazard of materials falling through a wall hole, and the lower edge of the near side of the hole is less than 4 inches above the floor, and the far side of the hole more than 5 feet above the next lower level, the hole shall be protected by a standard toeboard, or an enclosing screen either of solid construction, or as specified in paragraph (e)(11) of this section.
(c) Protection of open-sided floors, platforms, and runways. (1) Every open-sided floor or platform 4 feet or more above adjacent floor or ground level shall be guarded by a standard railing (or the equivalent as specified in paragraph (e)(3) of this section) on all open sides except where there is entrance to a ramp, stairway, or fixed ladder. The railing shall be provided with a toeboard wherever, beneath the open sides,
(i) Persons can pass,
(ii) There is moving machinery, or
(iii) There is equipment with which falling materials could create a hazard.
(2) Every runway shall be guarded by a standard railing (or the equivalent as specified in paragraph (e)(3) of this section) on all open sides 4 feet or more above floor or ground level. Wherever tools, machine parts, or materials are likely to be used on the runway, a toeboard shall also be provided on each exposed side.
Runways used exclusively for special purposes (such as oiling, shafting, or filling tank cars) may have the railing on one side omitted where operating conditions necessitate such omission, providing the falling hazard is minimized by using a runway of not less than 18 inches wide. Where persons entering upon runways become thereby exposed to machinery, electrical equipment, or other danger not a falling hazard, additional guarding than is here specified may be essential for protection.
(3) Regardless of height, open-sided floors, walkways, platforms, or runways above or adjacent to dangerous equipment, pickling or galvanizing tanks, degreasing units, and similar hazards shall be guarded with a standard railing and toe board.
(d) Stairway railings and guards. (1) Every flight of stairs having four or more risers shall be equipped with standard stair railings or standard handrails as specified in paragraphs (d)(1) (i) through (v) of this section, the width of the stair to be measured clear of all obstructions except handrails:
(i) On stairways less than 44 inches wide having both sides enclosed, at least one handrail, preferably on the right side descending.
(ii) On stairways less than 44 inches wide having one side open, at least one stair railing on open side.
(iii) On stairways less than 44 inches wide having both sides open, one stair railing on each side.
(iv) On stairways more than 44 inches wide but less than 88 inches wide, one handrail on each enclosed side and one stair railing on each open side.
(v) On stairways 88 or more inches wide, one handrail on each enclosed side, one stair railing on each open side, and one intermediate stair railing located approximately midway of the width.
(2) Winding stairs shall be equipped with a handrail offset to prevent walking on all portions of the treads having width less than 6 inches.
(e) Railing, toe boards, and cover specifications. (1) A standard railing shall consist of top rail, intermediate rail, and posts, and shall have a vertical height of 42 inches nominal from upper surface of top rail to floor, platform, runway, or ramp level. The top rail shall be smooth-surfaced throughout the length of the railing. The intermediate rail shall be approximately halfway between the top rail and the floor, platform, runway, or ramp. The ends of the rails shall not overhang the terminal posts except where such overhang does not constitute a projection hazard.
(2) A stair railing shall be of construction similar to a standard railing but the vertical height shall be not more than 34 inches nor less than 30 inches from upper surface of top rail to surface of tread in line with face of riser at forward edge of tread.
(3) [Reserved]
(i) For wood railings, the posts shall be of at least 2-inch by 4-inch stock spaced not to exceed 6 feet; the top and intermediate rails shall be of at least 2-inch by 4-inch stock. If top rail is made of two right-angle pieces of 1-inch by 4-inch stock, posts may be spaced on 8-foot centers, with 2-inch by 4-inch intermediate rail.
(ii) For pipe railings, posts and top and intermediate railings shall be at least 11/2 inches nominal diameter with posts spaced not more than 8 feet on centers.
(iii) For structural steel railings, posts and top and intermediate rails shall be of 2-inch by 2-inch by 3/8-inch angles or other metal shapes of equivalent bending strength with posts spaced not more than 8 feet on centers.
(iv) The anchoring of posts and framing of members for railings of all types shall be of such construction that the completed structure shall be capable of withstanding a load of at least 200 pounds applied in any direction at any point on the top rail.
(v) Other types, sizes, and arrangements of railing construction are acceptable provided they meet the following conditions:
(a) A smooth-surfaced top rail at a height above floor, platform, runway, or ramp level of 42 inches nominal;
(b) A strength to withstand at least the minimum requirement of 200 pounds top rail pressure;
(c) Protection between top rail and floor, platform, runway, ramp, or stair treads, equivalent at least to that afforded by a standard intermediate rail;
(4) A standard toeboard shall be 4 inches nominal in vertical height from its top edge to the level of the floor, platform, runway, or ramp. It shall be securely fastened in place and with not more than 1/4-inch clearance above floor level. It may be made of any substantial material either solid or with openings not over 1 inch in greatest dimension.
Where material is piled to such height that a standard toeboard does not provide protection, paneling from floor to intermediate rail, or to top rail shall be provided.
(5)(i) A handrail shall consist of a lengthwise member mounted directly on a wall or partition by means of brackets attached to the lower side of the handrail so as to offer no obstruction to a smooth surface along the top and both sides of the handrail. The handrail shall be of rounded or other section that will furnish an adequate handhold for anyone grasping it to avoid falling. The ends of the handrail should be turned in to the supporting wall or otherwise arranged so as not to constitute a projection hazard.
(ii) The height of handrails shall be not more than 34 inches nor less than 30 inches from upper surface of handrail to surface of tread in line with face of riser or to surface of ramp.
(iii) The size of handrails shall be: When of hardwood, at least 2 inches in diameter; when of metal pipe, at least 11/2 inches in diameter. The length of brackets shall be such as will give a clearance between handrail and wall or any projection thereon of at least 3 inches. The spacing of brackets shall not exceed 8 feet.
(iv) The mounting of handrails shall be such that the completed structure is capable of withstanding a load of at least 200 pounds applied in any direction at any point on the rail.
(6) All handrails and railings shall be provided with a clearance of not less than 3 inches between the handrail or railing and any other object.
(7) Floor opening covers may be of any material that meets the following strength requirements:
(i) Trench or conduit covers and their supports, when located in plant roadways, shall be designed to carry a truck rear-axle load of at least 20,000 pounds.
(ii) Manhole covers and their supports, when located in plant roadways, shall comply with local standard highway requirements if any; otherwise, they shall be designed to carry a truck rear-axle load of at least 20,000 pounds.
(iii) The construction of floor opening covers may be of any material that meets the strength requirements. Covers projecting not more than 1 inch above the floor level may be used providing all edges are chamfered to an angle with the horizontal of not over 30 degrees. All hinges, handles, bolts, or other parts shall set flush with the floor or cover surface.
(8) Skylight screens shall be of such construction and mounting that they are capable of withstanding a load of at least 200 pounds applied perpendicularly at any one area on the screen. They shall also be of such construction and mounting that under ordinary loads or impacts, they will not deflect downward sufficiently to break the glass below them. The construction shall be of grillwork with openings not more than 4 inches long or of slatwork with openings not more than 2 inches wide with length unrestricted.
(9) Wall opening barriers (rails, rollers, picket fences, and half doors) shall be of such construction and mounting that, when in place at the opening, the barrier is capable of withstanding a load of at least 200 pounds applied in any direction (except upward) at any point on the top rail or corresponding member.
(10) Wall opening grab handles shall be not less than 12 inches in length and shall be so mounted as to give 3 inches clearance from the side framing of the wall opening. The size, material, and anchoring of the grab handle shall be such that the completed structure is capable of withstanding a load of at least 200 pounds applied in any direction at any point of the handle.
(11) Wall opening screens shall be of such construction and mounting that they are capable of withstanding a load of at least 200 pounds applied horizontally at any point on the near side of the screen. They may be of solid construction, of grillwork with openings not more than 8 inches long, or of slatwork with openings not more than 4 inches wide with length unrestricted.
[39 FR 23502, June 27, 1974, as amended at 43 FR 49744, Oct. 24, 1978; 49 FR 5321, Feb. 10, 1984]
§ 1910.24 Fixed industrial stairs.
(a) Application of requirements. This section contains specifications for the safe design and construction of fixed general industrial stairs. This classification includes interior and exterior stairs around machinery, tanks, and other equipment, and stairs leading to or from floors, platforms, or pits. This section does not apply to stairs used for fire exit purposes, to construction operations to private residences, or to articulated stairs, such as may be installed on floating roof tanks or on dock facilities, the angle of which changes with the rise and fall of the base support.
(b) Where fixed stairs are required. Fixed stairs shall be provided for access from one structure level to another where operations necessitate regular travel between levels, and for access to operating platforms at any equipment which requires attention routinely during operations. Fixed stairs shall also be provided where access to elevations is daily or at each shift for such purposes as gauging, inspection, regular maintenance, etc., where such work may expose employees to acids, caustics, gases, or other harmful substances, or for which purposes the carrying of tools or equipment by hand is normally required. (It is not the intent of this section to preclude the use of fixed ladders for access to elevated tanks, towers, and similar structures, overhead traveling cranes, etc., where the use of fixed ladders is common practice.) Spiral stairways shall not be permitted except for special limited usage and secondary access situations where it is not practical to provide a conventional stairway. Winding stairways may be installed on tanks and similar round structures where the diameter of the structure is not less than five (5) feet.
(c) Stair strength. Fixed stairways shall be designed and constructed to carry a load of five times the normal live load anticipated but never of less strength than to carry safely a moving concentrated load of 1,000 pounds.
(d) Stair width. Fixed stairways shall have a minimum width of 22 inches.
(e) Angle of stairway rise. Fixed stairs shall be installed at angles to the horizontal of between 30° and 50°. Any uniform combination of rise/tread dimensions may be used that will result in a stairway at an angle to the horizontal within the permissible range. Table D–1 gives rise/tread dimensions which will produce a stairway within the permissible range, stating the angle to the horizontal produced by each combination. However, the rise/tread combinations are not limited to those given in Table D–1.
Table D-1------------------------------------------------------------------------ Tread Angle to horizontal Rise (in run (in inches) inches)------------------------------------------------------------------------30°35[min]...................................... 6\1/2\ 1132°08[min]...................................... 6\3/4\ 10\3/4\33°41[min]...................................... 7 10\1/2\35°16[min]...................................... 7\1/4\ 10\1/4\36°52[min]...................................... 7\1/2\ 1038°29[min]...................................... 7\3/4\ 9\3/4\40°08[min]...................................... 8 9\1/2\41°44[min]...................................... 8\1/4\ 9\1/4\43°22[min]...................................... 8\1/2\ 945°00[min]...................................... 8\3/4\ 8\3/4\46°38[min]...................................... 9 8\1/2\48°16[min]...................................... 9\1/4\ 8\1/4\49°54[min]...................................... 9\1/2\ 8------------------------------------------------------------------------
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(f) Stair treads. All treads shall be reasonably slip-resistant and the nosings shall be of nonslip finish. Welded bar grating treads without nosings are acceptable providing the leading edge can be readily identified by personnel descending the stairway and provided the tread is serrated or is of definite nonslip design. Rise height and tread width shall be uniform throughout any flight of stairs including any foundation structure used as one or more treads of the stairs.
(g) Stairway platforms. Stairway platforms shall be no less than the width of a stairway and a minimum of 30 inches in length measured in the direction of travel.
(h) Railings and handrails. Standard railings shall be provided on the open sides of all exposed stairways and stair platforms. Handrails shall be provided on at least one side of closed stairways preferably on the right side descending. Stair railings and handrails shall be installed in accordance with the provisions of §1910.23.
(i) Vertical clearance. Vertical clearance above any stair tread to an overhead obstruction shall be at least 7 feet measured from the leading edge of the tread.
[39 FR 23502, June 27, 1974, as amended at 43 FR 49744, Oct. 24, 1978; 49 FR 5321, Feb. 10, 1984] § 1910.25 Portable wood ladders.
(a) Application of requirements. This section is intended to prescribe rules and establish minimum requirements for the construction, care, and use of the common types of portable wood ladders, in order to insure safety under normal conditions of usage. Other types of special ladders, fruitpicker's ladders, combination step and extension ladders, stockroom step ladders, aisle-way step ladders, shelf ladders, and library ladders are not specifically covered by this section.
(b) Materials—(1) Requirements applicable to all wood parts. (i) All wood parts shall be free from sharp edges and splinters; sound and free from accepted visual inspection from shake, wane, compression failures, decay, or other irregularities. Low density wood shall not be used.
(ii) [Reserved]
(2) [Reserved]
(c) Construction requirements.
(1) [Reserved]
(2) Portable stepladders. Stepladders longer than 20 feet shall not be supplied. Stepladders as hereinafter specified shall be of three types:
Type I—Industrial stepladder, 3 to 20 feet for heavy duty, such as utilities, contractors, and industrial use.
Type II—Commercial stepladder, 3 to 12 feet for medium duty, such as painters, offices, and light industrial use.
Type III—Household stepladder, 3 to 6 feet for light duty, such as light household use.
(i) General requirements.
(a) [Reserved]
(b) A uniform step spacing shall be employed which shall be not more than 12 inches. Steps shall be parallel and level when the ladder is in position for use.
(c) The minimum width between side rails at the top, inside to inside, shall be not less than 111/2 inches. From top to bottom, the side rails shall spread at least 1 inch for each foot of length of stepladder.
(d)–(e) [Reserved]
(f) A metal spreader or locking device of sufficient size and strength to securely hold the front and back sections in open positions shall be a component of each stepladder. The spreader shall have all sharp points covered or removed to protect the user. For Type III ladder, the pail shelf and spreader may be combined in one unit (the so-called shelf-lock ladder).
(3) Portable rung ladders.
(i) [Reserved]
(ii) Single ladder. (a) Single ladders longer than 30 feet shall not be supplied.
(b) [Reserved]
(iii) Two-section ladder. (a) Two-section extension ladders longer than 60 feet shall not be supplied. All ladders of this type shall consist of two sections, one to fit within the side rails of the other, and arranged in such a manner that the upper section can be raised and lowered.
(b) [Reserved]
(iv) Sectional ladder. (a) Assembled combinations of sectional ladders longer than lengths specified in this subdivision shall not be used.
(b) [Reserved]
(v) Trestle and extension trestle ladder. (a) Trestle ladders, or extension sections or base sections of extension trestle ladders longer than 20 feet shall not be supplied.
(b) [Reserved]
(4) Special-purpose ladders.
(i) [Reserved]
(ii) Painter's stepladder. (a) Painter's stepladders longer than 12 feet shall not be supplied.
(b) [Reserved]
(iii) Mason's ladder. A mason's ladder is a special type of single ladder intended for use in heavy construction work.
(a) Mason's ladders longer than 40 feet shall not be supplied.
(b) [Reserved]
(5) Trolley and side-rolling ladders—(i) Length. Trolley ladders and side-rolling ladders longer than 20 feet should not be supplied.
(ii) [Reserved]
(d) Care and use of ladders—(1) Care. To insure safety and serviceability the following precautions on the care of ladders shall be observed:
(i) Ladders shall be maintained in good condition at all times, the joint between the steps and side rails shall be tight, all hardware and fittings securely attached, and the movable parts shall operate freely without binding or undue play.
(ii) Metal bearings of locks, wheels, pulleys, etc., shall be frequently lubricated.
(iii) Frayed or badly worn rope shall be replaced.
(iv) Safety feet and other auxiliary equipment shall be kept in good condition to insure proper performance.
(v)–(ix) [Reserved]
(x) Ladders shall be inspected frequently and those which have developed defects shall be withdrawn from service for repair or destruction and tagged or marked as “Dangerous, Do Not Use.”
(xi) Rungs should be kept free of grease and oil.
(2) Use. The following safety precautions shall be observed in connection with the use of ladders:
(i) Portable rung and cleat ladders shall, where possible, be used at such a pitch that the horizontal distance from the top support to the foot of the ladder is one-quarter of the working length of the ladder (the length along the ladder between the foot and the top support). The ladder shall be so placed as to prevent slipping, or it shall be lashed, or held in position. Ladders shall not be used in a horizontal position as platforms, runways, or scaffolds;
(ii) Ladders for which dimensions are specified should not be used by more than one man at a time nor with ladder jacks and scaffold planks where use by more than one man is anticipated. In such cases, specially designed ladders with larger dimensions of the parts should be procured;
(iii) Portable ladders shall be so placed that the side rails have a secure footing. The top rest for portable rung and cleat ladders shall be reasonably rigid and shall have ample strength to support the applied load;
(iv) Ladders shall not be placed in front of doors opening toward the ladder unless the door is blocked upon, locked, or guarded;
(v) Ladders shall not be placed on boxes, barrels, or other unstable bases to obtain additional height;
(vi)–(vii) [Reserved]
(viii) Ladders with broken or missing steps, rungs, or cleats, broken side rails, or other faulty equipment shall not be used; improvised repairs shall not be made;
(ix) Short ladders shall not be spliced together to provide long sections;
(x) Ladders made by fastening cleats across a single rail shall not be used;
(xi) Ladders shall not be used as guys, braces, or skids, or for other than their intended purposes;
(xii) Tops of the ordinary types of stepladders shall not be used as steps;
(xiii) On two-section extension ladders the minimum overlap for the two sections in use shall be as follows:
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------------------------------------------------------------------------ Overlap Size of ladder (feet) (feet)------------------------------------------------------------------------Up to and including 36...................................... 3Over 36 up to and including 48.............................. 4Over 48 up to and including 60.............................. 5------------------------------------------------------------------------
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(xiv) Portable rung ladders with reinforced rails (see paragraphs (c)(3) (ii)(c) and (iii)(d) this section) shall be used only with the metal reinforcement on the under side;
(xv) No ladder should be used to gain access to a roof unless the top of the ladder shall extend at least 3 feet above the point of support, at eave, gutter, or roofline;
(xvi) [Reserved]
(xvii) Middle and top sections of sectional or window cleaner's ladders should not be used for bottom section unless the user equips them with safety shoes;
(xviii) [Reserved]
(xix) The user should equip all portable rung ladders with nonslip bases when there is a hazard of slipping. Nonslip bases are not intended as a substitute for care in safely placing, lashing, or holding a ladder that is being used upon oily, metal, concrete, or slippery surfaces;
(xx) The bracing on the back legs of step ladders is designed solely for increasing stability and not for climbing.
[39 FR 23502, June 27, 1974, as amended at 43 FR 49744, Oct. 24, 1978; 49 FR 5321, Feb. 10, 1984] § 1910.26 Portable metal ladders.
(a) Requirements—(1) General. Specific design and construction requirements are not part of this section because of the wide variety of metals and design possibilities. However, the design shall be such as to produce a ladder without structural defects or accident hazards such as sharp edges, burrs, etc. The metal selected shall be of sufficient strength to meet the test requirements, and shall be protected against corrosion unless inherently corrosion-resistant.
(i)–(ii) [Reserved]
(iii) The spacing of rungs or steps shall be on 12-inch centers.
(iv) [Reserved]
(v) Rungs and steps shall be corrugated, knurled, dimpled, coated with skid-resistant material, or otherwise treated to minimize the possibility of slipping.
(2) General specifications—straight and extension ladders. (i) The minimum width between side rails of a straight ladder or any section of an extension ladder shall be 12 inches.
(ii) The length of single ladders or individual sections of ladders shall not exceed 30 feet. Two-section ladders shall not exceed 48 feet in length and over two-section ladders shall not exceed 60 feet in length.
(iii) Based on the nominal length of the ladder, each section of a multisection ladder shall overlap the adjacent section by at least the number of feet stated in the following:
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------------------------------------------------------------------------ Overlap Normal length of ladder (feet) (feet)------------------------------------------------------------------------Up to and including 36...................................... 3Over 36, up to and including 48............................. 4Over 48, up to 60........................................... 5------------------------------------------------------------------------
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(iv) Extension ladders shall be equipped with positive stops which will insure the overlap specified in the table above.
(3) General specifications—step ladders.
(i)–(ii) [Reserved]
(iii) The length of a stepladder is measured by the length of the front rail. To be classified as a standard length ladder, the measured length shall be within plus or minus one-half inch of the specified length. Stepladders shall not exceed 20 feet in length.
(iv)–(vi) [Reserved]
(vii) The bottoms of the four rails are to be supplied with insulating nonslip material for the safety of the user.
(viii) A metal spreader or locking device of sufficient size and strength to securely hold the front and back sections in the open position shall be a component of each stepladder. The spreader shall have all sharp points or edges covered or removed to protect the user.
(4) General specifications—trestles and extension trestle ladders. (i) Trestle ladders or extension sections or base sections of extension trestle ladders shall be not more than 20 feet in length.
(ii) [Reserved]
(5) General specifications—platform ladders. (i) The length of a platform ladder shall not exceed 20 feet. The length of a platform ladder shall be measured along the front rail from the floor to the platform.
(ii) [Reserved]
(b) [Reserved]
(c) Care and maintenance of ladders—(1) General. To get maximum serviceability, safety, and to eliminate unnecessary damage of equipment, good safe practices in the use and care of ladder equipment must be employed by the users.
The following rules and regulations are essential to the life of the equipment and the safety of the user.
(2) Care of ladders.
(i)–(iii) [Reserved]
(iv) Ladders must be maintained in good usable condition at all times.
(v) [Reserved]
(vi) If a ladder is involved in any of the following, immediate inspection is necessary:
(a) If ladders tip over, inspect ladder for side rails dents or bends, or excessively dented rungs; check all rung-to- side-rail connections; check hardware connections; check rivets for shear.
(b)–(c) [Reserved]
(d) If ladders are exposed to oil and grease, equipment should be cleaned of oil, grease, or slippery materials. This can easily be done with a solvent or steam cleaning.
(vii) Ladders having defects are to be marked and taken out of service until repaired by either maintenance department or the manufacturer.
(3) Use of ladders. (i). A simple rule for setting up a ladder at the proper angle is to place the base a distance from the vertical wall equal to one-fourth the working length of the ladder.
(ii) Portable ladders are designed as a one-man working ladder based on a 200-pound load.
(iii) The ladder base section must be placed with a secure footing.
(iv) The top of the ladder must be placed with the two rails supported, unless equipped with a single support attachment.
(v) When ascending or descending, the climber must face the ladder.
(vi) Ladders must not be tied or fastened together to provide longer sections. They must be equipped with the hardware fittings necessary if the manufacturer endorses extended uses.
(vii) Ladders should not be used as a brace, skid, guy or gin pole, gangway, or for other uses than that for which they were intended, unless specifically recommended for use by the manufacturer.
(viii) See §1910.333(c) for work practices to be used when work is performed on or near electric circuits.
[39 FR 23502, June 27, 1974, as amended at 43 FR 49745, Oct. 24, 1978; 49 FR 5321, Feb. 10, 1984; 55 FR 32014, Aug. 6, 1990] § 1910.27 Fixed ladders.
(a) Design requirements—(1) Design considerations. All ladders, appurtenances, and fastenings shall be designed to meet the following load requirements:
(i) The minimum design live load shall be a single concentrated load of 200 pounds.
(ii) The number and position of additional concentrated live-load units of 200 pounds each as determined from anticipated usage of the ladder shall be considered in the design.
(iii) The live loads imposed by persons occupying the ladder shall be considered to be concentrated at such points as will cause the maximum stress in the structural member being considered.
(iv) The weight of the ladder and attached appurtenances together with the live load shall be considered in the design of rails and fastenings.
(2) Design stresses. Design stresses for wood components of ladders shall not exceed those specified in §1910.25. All wood parts of fixed ladders shall meet the requirements of §1910.25(b).
For fixed ladders consisting of wood side rails and wood rungs or cleats, used at a pitch in the range 75 degrees to 90 degrees, and intended for use by no more than one person per section, single ladders as described in §1910.25(c)(3)(ii) are acceptable.
(b) Specific features—(1) Rungs and cleats. (i) All rungs shall have a minimum diameter of three-fourths inch for metal ladders, except as covered in paragraph (b)(7)(i) of this section and a minimum diameter of 11/8 inches for wood ladders.
(ii) The distance between rungs, cleats, and steps shall not exceed 12 inches and shall be uniform throughout the length of the ladder.
(iii) The minimum clear length of rungs or cleats shall be 16 inches.
(iv) Rungs, cleats, and steps shall be free of splinters, sharp edges, burrs, or projections which may be a hazard.
(v) The rungs of an individual-rung ladder shall be so designed that the foot cannot slide off the end. A suggested design is shown in figure D–1.
 Figure D–1—Suggested Design for Rungs on Individual-rung Ladders.
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(2) Side rails. Side rails which might be used as a climbing aid shall be of such cross sections as to afford adequate gripping surface without sharp edges, splinters, or burrs.
(3) Fastenings. Fastenings shall be an integral part of fixed ladder design.
(4) Splices. All splices made by whatever means shall meet design requirements as noted in paragraph (a) of this section. All splices and connections shall have smooth transition with original members and with no sharp or extensive projections.
(5) Electrolytic action. Adequate means shall be employed to protect dissimilar metals from electrolytic action when such metals are joined.
(6) Welding. All welding shall be in accordance with the “Code for Welding in Building Construction” (AWSD1.0–1966).
(7) Protection from deterioration. (i) Metal ladders and appurtenances shall be painted or otherwise treated to resist corrosion and rusting when location demands. Ladders formed by individual metal rungs imbedded in concrete, which serve as access to pits and to other areas under floors, are frequently located in an atmosphere that causes corrosion and rusting. To increase rung life in such atmosphere, individual metal rungs shall have a minimum diameter of 1 inch or shall be painted or otherwise treated to resist corrosion and rusting.
(ii) Wood ladders, when used under conditions where decay may occur, shall be treated with a nonirritating preservative, and the details shall be such as to prevent or minimize the accumulation of water on wood parts.
(iii) When different types of materials are used in the construction of a ladder, the materials used shall be so treated as to have no deleterious effect one upon the other.
 Figure D–2—Rail Ladder With Bar Steel Rails and Round Steel Rungs
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(c) Clearance—(1) Climbing side. On fixed ladders, the perpendicular distance from the centerline of the rungs to the nearest permanent object on the climbing side of the ladder shall be 36 inches for a pitch of 76 degrees, and 30 inches for a pitch of 90 degrees (fig. D–2 of this section), with minimum clearances for intermediate pitches varying between these two limits in proportion to the slope, except as provided in subparagraphs (3) and (5) of this paragraph.
(2) Ladders without cages or wells. A clear width of at least 15 inches shall be provided each way from the centerline of the ladder in the climbing space, except when cages or wells are necessary.
(3) Ladders with cages or baskets. Ladders equipped with cage or basket are excepted from the provisions of subparagraphs (1) and (2) of this paragraph, but shall conform to the provisions of paragraph (d)(1)(v) of this section. Fixed ladders in smooth-walled wells are excepted from the provisions of subparagraph (1) of this paragraph, but shall conform to the provisions of paragraph (d)(1)(vi) of this section.
(4) Clearance in back of ladder. The distance from the centerline of rungs, cleats, or steps to the nearest permanent object in back of the ladder shall be not less than 7 inches, except that when unavoidable obstructions are encountered, minimum clearances as shown in figure D–3 shall be provided.
Minimum Ladder Clearances
 Figure D–3—Clearance for Unavoidable Obstruction at Rear of Fixed Ladder
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(5) Clearance in back of grab bar. The distance from the centerline of the grab bar to the nearest permanent object in back of the grab bars shall be not less than 4 inches. Grab bars shall not protrude on the climbing side beyond the rungs of the ladder which they serve.
(6) Step-across distance. The step-across distance from the nearest edge of ladder to the nearest edge of equipment or structure shall be not more than 12 inches, or less than 21/2 inches (fig. D–4).
 Figure D–4—Ladder Far from Wall
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(7) Hatch cover. Counterweighted hatch covers shall open a minimum of 60 degrees from the horizontal. The distance from the centerline of rungs or cleats to the edge of the hatch opening on the climbing side shall be not less than 24 inches for offset wells or 30 inches for straight wells. There shall be not protruding potential hazards within 24 inches of the centerline of rungs or cleats; any such hazards within 30 inches of the centerline of the rungs or cleats shall be fitted with deflector plates placed at an angle of 60 degrees from the horizontal as indicated in figure D–5. The relationship of a fixed ladder to an acceptable counterweighted hatch cover is illustrated in figure D–6.
(d) Special requirements—(1) Cages or wells. (i) Cages or wells (except on chimney ladders) shall be built, as shown on the applicable drawings, covered in detail in figures D–7, D–8, and D–9, or of equivalent construction.
(ii) Cages or wells (except as provided in subparagraph (5) of this paragraph) conforming to the dimensions shown in figures D–7, D–8, and D–9 shall be provided on ladders of more than 20 feet to a maximum unbroken length of 30 feet.
 Figure D–5—Deflector Plates for Head Hazards
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 Figure D–6—Relationship of Fixed Ladder to a Safe Access Hatch
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(iii) Cages shall extend a minimum of 42 inches above the top of landing, unless other acceptable protection is provided.
(iv) Cages shall extend down the ladder to a point not less than 7 feet nor more than 8 feet above the base of the ladder, with bottom flared not less than 4 inches, or portion of cage opposite ladder shall be carried to the base.
(v) Cages shall not extend less than 27 nor more than 28 inches from the centerline of the rungs of the ladder. Cage shall not be less than 27 inches in width. The inside shall be clear of projections. Vertical bars shall be located at a maximum spacing of 40 degrees around the circumference of the cage; this will give a maximum spacing of approximately 91/2 inches, center to center.
(vi) Ladder wells shall have a clear width of at least 15 inches measured each way from the centerline of the ladder. Smooth-walled wells shall be a minimum of 27 inches from the centerline of rungs to the well wall on the climbing side of the ladder. Where other obstructions on the climbing side of the ladder exist, there shall be a minimum of 30 inches from the centerline of the rungs.
 Figure D–7—Cages for Ladders More Than 20 Feet High
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 Figure D–8—Clearance Diagram for Fixed Ladder in Well
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 Figure D–9—Cages—Special applications.
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(2) Landing platforms. When ladders are used to ascend to heights exceeding 20 feet (except on chimneys), landing platforms shall be provided for each 30 feet of height or fraction thereof, except that, where no cage, well, or ladder safety device is provided, landing platforms shall be provided for each 20 feet of height or fraction thereof. Each ladder section shall be offset from adjacent sections. Where installation conditions (even for a short, unbroken length) require that adjacent sections be offset, landing platforms shall be provided at each offset.
(i) Where a man has to step a distance greater than 12 inches from the centerline of the rung of a ladder to the nearest edge of structure or equipment, a landing platform shall be provided. The minimum step-across distance shall be 21/2 inches.
(ii) All landing platforms shall be equipped with standard railings and toeboards, so arranged as to give safe access to the ladder. Platforms shall be not less than 24 inches in width and 30 inches in length.
(iii) One rung of any section of ladder shall be located at the level of the landing laterally served by the ladder. Where access to the landing is through the ladder, the same rung spacing as used on the ladder shall be used from the landing platform to the first rung below the landing.
(3) Ladder extensions. The side rails of through or side-step ladder extensions shall extend 31/2 feet above parapets and landings. For through ladder extensions, the rungs shall be omitted from the extension and shall have not less than 18 nor more than 24 inches clearance between rails. For side-step or offset fixed ladder sections, at landings, the side rails and rungs shall be carried to the next regular rung beyond or above the 31/2 feet minimum (fig. D–10).
 Figure D–10—Offset Fixed Ladder Sections
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(4) Grab bars. Grab bars shall be spaced by a continuation of the rung spacing when they are located in the horizontal position. Vertical grab bars shall have the same spacing as the ladder side rails. Grab-bar diameters shall be the equivalent of the round-rung diameters.
(5) Ladder safety devices. Ladder safety devices may be used on tower, water tank, and chimney ladders over 20 feet in unbroken length in lieu of cage protection. No landing platform is required in these cases. All ladder safety devices such as those that incorporate lifebelts, friction brakes, and sliding attachments shall meet the design requirements of the ladders which they serve.
(e) Pitch—(1) Preferred pitch. The preferred pitch of fixed ladders shall be considered to come in the range of 75 degrees and 90 degrees with the horizontal (fig. D–11).
 Figure D–11—Pitch of Fixed Ladders
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(2) Substandard pitch. Fixed ladders shall be considered as substandard if they are installed within the substandard pitch range of 60 and 75 degrees with the horizontal. Substandard fixed ladders are permitted only where it is found necessary to meet conditions of installation. This substandard pitch range shall be considered as a critical range to be avoided, if possible.
(3) Scope of coverage in this section. This section covers only fixed ladders within the pitch range of 60 degrees and 90 degrees with the horizontal.
(4) Pitch greater than 90 degrees. Ladders having a pitch in excess of 90 degrees with the horizontal are prohibited.
(f) Maintenance. All ladders shall be maintained in a safe condition. All ladders shall be inspected regularly, with the intervals between inspections being determined by use and exposure. § 1910.28 Safety requirements for scaffolding.
(a) General requirements for all scaffolds. (1) Scaffolds shall be furnished and erected in accordance with this standard for persons engaged in work that cannot be done safely from the ground or from solid construction, except that ladders used for such work shall conform to §1910.25 and §1910.26.
(2) The footing or anchorage for scaffolds shall be sound, rigid, and capable of carrying the maximum intended load without settling or displacement. Unstable objects such as barrels, boxes, loose brick, or concrete blocks shall not be used to support scaffolds or planks.
(3) [Reserved]
(4) Scaffolds and their components shall be capable of supporting without failure at least four times the maximum intended load.
(5) Scaffolds and other devices mentioned or described in this section shall be maintained in safe condition. Scaffolds shall not be altered or moved horizontally while they are in use or occupied.
(6) Any scaffold damaged or weakened from any cause shall be immediately repaired and shall not be used until repairs have been completed.
(7) Scaffolds shall not be loaded in excess of the working load for which they are intended.
(8) All load-carrying timber members of scaffold framing shall be a minimum of 1,500 f. (Stress Grade) construction grade lumber. All dimensions are nominal sizes as provided in the American Lumber Standards, except that where rough sizes are noted, only rough or undressed lumber of the size specified will satisfy minimum requirements. (Note: Where nominal sizes of lumber are used in place of rough sizes, the nominal size lumber shall be such as to provide equivalent strength to that specified in tables D–7 through D–12 and D–16.)
(9) All planking shall be Scaffold Grade as recognized by grading rules for the species of wood used. The maximum permissible spans for 2- × 9-inch or wider planks are shown in the following table:
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------------------------------------------------------------------------ Material --------------------------------------- Full thickness Nominal undressed lumber thickness ------------------------ lumber --------------- ------------------------------------------------------------------------Working load (p.s.f.)........... 25 50 75 25 50Permissible span (ft.).......... 10 8 6 8 9------------------------------------------------------------------------
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The maximum permissible span for 11/4×9-inch or wider plank of full thickness is 4 feet with medium loading of 50 p.s.f.
(10) Nails or bolts used in the construction of scaffolds shall be of adequate size and in sufficient numbers at each connection to develop the designed strength of the scaffold. Nails shall not be subjected to a straight pull and shall be driven full length.
(11) All planking or platforms shall be overlapped (minimum 12 inches) or secured from movement.
(12) An access ladder or equivalent safe access shall be provided.
(13) Scaffold planks shall extend over their end supports not less than 6 inches nor more than 18 inches.
(14) The poles, legs, or uprights of scaffolds shall be plumb, and securely and rigidly braced to prevent swaying and displacement.
(15) Materials being hoisted onto a scaffold shall have a tag line.
(16) Overhead protection shall be provided for men on a scaffold exposed to overhead hazards.
(17) Scaffolds shall be provided with a screen between the toeboard and the guardrail, extending along the entire opening, consisting of No. 18 gauge U.S. Standard Wire one-half-inch mesh or the equivalent, where persons are required to work or pass under the scaffolds.
(18) Employees shall not work on scaffolds during storms or high winds.
(19) Employees shall not work on scaffolds which are covered with ice or snow, unless all ice or snow is removed and planking sanded to prevent slipping.
(20) Tools, materials, and debris shall not be allowed to accumulate in quantities to cause a hazard.
(21) Only treated or protected fiber rope shall be used for or near any work involving the use of corrosive substances or chemicals.
(22) Wire or fiber rope used for scaffold suspension shall be capable of supporting at least six times the intended load.
(23) When acid solutions are used for cleaning buildings over 50 feet in height, wire rope supported scaffolds shall be used.
(24) The use of shore scaffolds or lean-to scaffolds is prohibited.
(25) Lumber sizes, when used in this section, refer to nominal sizes except where otherwise stated.
(26) Scaffolds shall be secured to permanent structures, through use of anchor bolts, reveal bolts, or other equivalent means. Window cleaners' anchor bolts shall not be used.
(27) Special precautions shall be taken to protect scaffold members, including any wire or fiber ropes, when using a heat-producing process.
(b) General requirements for wood pole scaffolds. (1) Scaffold poles shall bear on a foundation of sufficient size and strength to spread the load from the poles over a sufficient area to prevent settlement. All poles shall be set plumb.
(2) Where wood poles are spliced, the ends shall be squared and the upper section shall rest squarely on the lower section. Wood splice plates shall be provided on at least two adjacent sides and shall not be less than 4 feet 0 inches in length, overlapping the abutted ends equally, and have the same width and not less than the cross-sectional area of the pole. Splice plates of other materials of equivalent strength may be used.
(3) Independent pole scaffolds shall be set as near to the wall of the building as practicable.
(4) All pole scaffolds shall be securely guyed or tied to the building or structure. Where the height or length exceeds 25 feet, the scaffold shall be secured at intervals not greater than 25 feet vertically and horizontally.
(5) Putlogs or bearers shall be set with their greater dimensions vertical, long enough to project over the ledgers of the inner and outer rows of poles at least 3 inches for proper support.
(6) Every wooden putlog on single pole scaffolds shall be reinforced with a 3/16×2-inch steel strip or equivalent secured to its lower edge throughout its entire length.
(7) Ledgers shall be long enough to extend over two pole spaces. Ledgers shall not be spliced between the poles. Ledgers shall be reinforced by bearing blocks securely nailed to the side of the pole to form a support for the ledger.
(8) Diagonal bracing shall be provided to prevent the poles from moving in a direction parallel with the wall of the building, or from buckling.
(9) Cross bracing shall be provided between the inner and outer sets of poles in independent pole scaffolds. The free ends of pole scaffolds shall be cross braced.
(10) Full diagonal face bracing shall be erected across the entire face of pole scaffolds in both directions. The braces shall be spliced at the poles.
(11) Platform planks shall be laid with their edges close together so the platform will be tight with no spaces through which tools or fragments of material can fall.
(12) Where planking is lapped, each plank shall lap its end supports at least 12 inches. Where the ends of planks abut each other to form a flush floor, the butt joint shall be at the centerline of a pole. The abutted ends shall rest on separate bearers. Intermediate beams shall be provided where necessary to prevent dislodgment of planks due to deflection, and the ends shall be nailed or cleated to prevent their dislodgment.
(13) When a scaffold turns a corner, the platform planks shall be laid to prevent tipping. The planks that meet the corner putlog at an angle shall be laid first, extending over the diagonally placed putlog far enough to have a good safe bearing, but not far enough to involve any danger from tipping. The planking running in the opposite direction at right angles shall be laid so as to extend over and rest on the first layer of planking.
(14) When moving platforms to the next level, the old platform shall be left undisturbed until the new putlogs or bearers have been set in place, ready to receive the platform planks.
(15) Guardrails not less than 2 × 4 inches or the equivalent and not less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1 × 4-inch lumber or equivalent, and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(16) All wood pole scaffolds 60 feet or less in height shall be constructed and erected in accordance with tables D–7 through D–12 of this section. If they are over 60 feet in height they shall be designed by a registered professional engineer and constructed and erected in accordance with such design. A copy of the typical drawings and specifications shall be made available to the employer and for inspection purposes.
(17) Wood-pole scaffolds shall not be erected beyond the reach of effective firefighting apparatus.
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Table D-7_Minimum Nominal Size and Maximum Spacing of Members of Single Pole Scaffolds_Light Duty------------------------------------------------------------------------ Maximum height of scaffold ---------------------------------------- 20 feet 60 feet------------------------------------------------------------------------Uniformly distributed load..... Not to exceed 25 pounds per square foot..Poles or uprights.............. 2 by 4 in.......... 4 by 4 in.Pole spacing (longitudinal).... 6 ft. 0 in......... 10 ft. 0 in.Maximum width of scaffold...... 5 ft. 0 in......... 5 ft. 0 in.Bearers or putlogs to 3 ft. 0 2 by 4 in.......... 2 by 4 in. in. width.Bearers or putlogs to 5 ft. 0 2 by 6 in. or 3 by 2 by 6 in. or 3 by in. width. 4 in. 4 in.(rough).Ledgers........................ 1 by 4 in.......... 1\1/4\ by 9 in.Planking....................... 1\1/4\ by 9 in. 2 by 9 in. (rough).Vertical spacing of horizontal 7 ft. 0 in......... 7 ft. 0 in. members.Bracing, horizontal and 1 by 4 in.......... 1 by 4 in. diagonal.Tie-ins........................ 1 by 4 in.......... 1 by 4 in.Toeboards...................... 4 in. high 4 in. high (minimum). (minimum).Guardrail...................... 2 by 4 in.......... 2 by 4 in.------------------------------------------------------------------------All members except planking are used on edge.
Table D-8_Minimum Nominal Size and Maximum Spacing of Members of Single Pole Scaffolds_Medium Duty ---------------------------------------------------Uniformly Not to exceed 50 pounds per square distributed foot. loadMaximum height 60 ft. of scaffoldPoles or 4 by 4 in. uprightsPole spacing 8 ft. 0 in. (longitudinal)Maximum width 5 ft. 0 in. of scaffoldBearers or 2 by 9 in. or 3 by 4 in. putlogsSpacing of 8 ft. 0 in. bearers or putlogsLedgers 2 by 9 in.Vertical 9 ft. 0 in. spacing of horizontal membersBracing, 1 by 6 in. or 1\1/4\ by 4 in. horizontalBracing, 1 by 4 in. diagonalTie-ins 1 by 4 in.Planking 2 by 9 in.Toeboards 4 in. high (minimum).Guardrail 2 by 4 in.------------------------------------------------------------------------All members except planking are used on edge.
Table D-9_Minimum Nominal Size and Maximum Spacing of Members of Single Pole Scaffolds_Heavy Duty ---------------------------------------------------Uniformly Not to exceed 75 pounds per square distributed foot. loadMaximum height 60 ft. of scaffoldPoles or 4 by 4 in. uprightsPole spacing 6 ft. 0 in. (longitudinal)Maximum width 5 ft. 0 in. of scaffoldBearers or 2 by 9 in. or 3 by 5 in. (rough). putlogsSpacing of 6 ft. 0 in. bearers or putlogsLedgers 2 by 9 in.Vertical 6 ft. 6 in. spacing of horizontal membersBracing, 2 by 4 in. horizontal and diagonalTie-ins 1 by 4 in.Planking 2 by 9 in.Toeboards 4 in. high (minimum).Guardrail 2 by 4 in.------------------------------------------------------------------------All members except planking are used on edge.
Table D-10_Minimum Nominal Size and Maximum Spacing of Members of Independent Pole Scaffolds_Light Duty------------------------------------------------------------------------ Maximum height of scaffold ---------------------------------------- 20 feet 60 feet------------------------------------------------------------------------Uniformly distributed load..... Not to exceed 25 pounds per square foot..Poles or uprights.............. 2 by 4 in.......... 4 by 4 in.Pole spacing (longitudinal).... 6 ft. 0 in......... 10 ft. 0 in.Pole spacing (transverse)...... 6 ft. 0 in......... 10 ft. 0 in.Ledgers........................ 1\1/4\ by 4 in..... 1\1/4\ by 9 in.Bearers to 3 ft. 0 in. span.... 2 by 4 in.......... 2 by 4 in.Bearers to 10 ft. 0 in. span... 2 by 6 in. or 3 by 2 by 9 (rough) or 4 in. 3 by 8 in.Planking....................... 1\1/4\ by 9 in..... 2 by 9 in.Vertical spacing of horizontal 7 ft. 0 in......... 7 ft. 0 in. members.Bracing, horizontal and 1 by 4 in.......... 1 by 4 in. diagonal.Tie-ins........................ 1 by 4 in.......... 1 by 4 in.Toeboards...................... 4 in. high......... 4 in. high (minimum).Guardrail...................... 2 by 4 in.......... 2 by 4 in.------------------------------------------------------------------------All members except planking are used on edge.
Table D-11_Minimum Nominal Size and Maximum Spacing of Members of Independent Pole Scaffolds_Medium Duty ---------------------------------------------------Uniformly Not to exceed 50 pounds per square distributed foot. loadMaximum height 60 ft. of scaffoldPoles or 4 by 4 in. uprightsPole spacing 8 ft. 0 in. (longitudinal)Pole spacing 8 ft. 0 in. (transverse)Ledgers 2 by 9 in.Vertical 6 ft. 0 in. spacing of horizontal membersSpacing of 8 ft. 0 in. bearersBearers 2 by 9 in. (rough) or 2 by 10 in.Bracing, 1 by 6 in. or 1\1/4\ by 4 in. horizontalBracing, 1 by 4 in. diagonalTie-ins 1 by 4 in.Planking 2 by 9 in.Toeboards 4 in. high (minimum).Guardrail 2 by 4 in.------------------------------------------------------------------------All members except planking are used on edge.
Table D-12_Minimum Nominal Size and Maximum Spacing of Members of Independent Pole Scaffolds_Heavy Duty ---------------------------------------------------Uniformly Not to exceed 75 pounds per square distributed foot. loadMaximum height 60 ft. of scaffoldPoles or 4 by 4 in. uprightsPole spacing 6 ft. 0 in. (longitudinal)Pole spacing 8 ft. 0 in. (transverse)Ledgers 2 by 9 in.Vertical 4 ft. 6 in. spacing of horizontal membersBearers 2 by 9 in. (rough).Bracing, 2 by 4 in. horizontal and diagonalTie-ins 1 by 4 in.Planking 2 by 9 in.Toeboards 4 in. high (minimum).Guardrail 2 by 4 in.------------------------------------------------------------------------All members except planking are used on edge.
Table D-13_Tube and Coupler Scaffolds_Light Duty ---------------------------------------------------Uniformly Not to exceed 25 p.s.f. distributed loadpost spacing 10 ft. 0 in. (longitudinal)Post spacing 6 ft. 0 in. (transverse)------------------------------------------------------------------------
------------------------------------------------------------------------ Additional planked Working levels levels Maximum height------------------------------------------------------------------------ 1 8 125 ft. 2 4 125 ft. 3 0 91 ft. 0 in.------------------------------------------------------------------------
Table D-14_Tube and Coupler Scaffolds_Medium Duty ---------------------------------------------------Uniformly Not to exceed 50 p.s.f. distributed loadPost spacing 8 ft. 0 in. (longitudinal)Post spacing 6 ft. 0 in. (transverse)------------------------------------------------------------------------
------------------------------------------------------------------------ Additional planked Working levels levels Maximum height------------------------------------------------------------------------ 1 6 125 ft. 2 0 78 ft. 0 in.------------------------------------------------------------------------
Table D-15_Tube and Coupler Scaffolds_Heavy Duty ---------------------------------------------------Uniformly Not to exceed 75 p.s.f. distributed loadPost spacing 6 ft. 6 in. (longitudinal)Post spacing 6 ft. 0 in. (transverse)------------------------------------------------------------------------
------------------------------------------------------------------------ Additional planked Working levels levels Maximum height------------------------------------------------------------------------ 1 6 125 ft.------------------------------------------------------------------------
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(c) Tube and coupler scaffolds. (1) A light-duty tube and coupler scaffold shall have all posts, bearers, runners, and bracing of nominal 2-inch O.D. steel tubing. The posts shall be spaced no more than 6 feet apart by 10 feet along the length of the scaffold. Other structural metals when used must be designed to carry an equivalent load.
(2) A medium-duty tube and coupler scaffold shall have all posts, runners, and bracing of nominal 2-inch O.D. steel tubing. Posts spaced not more than 6 feet apart by 8 feet along the length of the scaffold shall have bearers of nominal 21/2-inch O.D. steel tubing. Posts spaced not more than 5 feet apart by 8 feet along the length of the scaffold shall have bearers of nominal 2-inch O.D. steel tubing. Other structural metals when used must be designed to carry an equivalent load.
(3) A heavy-duty tube and coupler scaffold shall have all posts, runners, and bracing of nominal 2-inch O.D. steel tubing, with the posts spaced not more than 6 feet apart by 6 feet 6 inches along the length of the scaffold. Other structural metals when used must be designed to carry an equivalent load.
(4) Tube and coupler scaffolds shall be limited in heights and working levels to those permitted in tables D–13, 14, and 15, of this section. Drawings and specifications of all tube and coupler scaffolds above the limitations in tables D–13, 14, and 15 of this section shall be designed by a registered professional engineer and copies made available to the employer and for inspection purposes.
(5) All tube and coupler scaffolds shall be constructed and erected to support four times the maximum intended loads as set forth in tables D–13, 14, and 15 of this section, or as set forth in the specifications by a registered professional engineer, copies which shall be made available to the employer and for inspection purposes.
(6) All tube and coupler scaffolds shall be erected by competent and experienced personnel.
(7) Posts shall be accurately spaced, erected on suitable bases, and maintained plumb.
(8) Runners shall be erected along the length of the scaffold located on both the inside and the outside posts at even height. Runners shall be interlocked to form continuous lengths and coupled to each post. The bottom runners shall be located as close to the base as possible. Runners shall be placed not more than 6 feet 6 inches on centers.
(9) Bearers shall be installed transversely between posts and shall be securely coupled to the posts bearing on the runner coupler. When coupled directly to the runners, the coupler must be kept as close to the posts as possible.
(10) Bearers shall be at least 4 inches but not more than 12 inches longer than the post spacing or runner spacing. Bearers may be cantilevered for use as brackets to carry not more than two planks.
(11) Cross bracing shall be installed across the width of the scaffold at least every third set of posts horizontally and every fourth runner vertically. Such bracing shall extend diagonally from the inner and outer runners upward to the next outer and inner runners.
(12) Longitudinal diagonal bracing shall be installed at approximately a 45-degree angle from near the base of the first outer post upward to the extreme top of the scaffold. Where the longitudinal length of the scaffold permits, such bracing shall be duplicated beginning at every fifth post. In a similar manner, longitudinal diagonal bracing shall also be installed from the last post extending back and upward toward the first post. Where conditions preclude the attachment of this bracing to the posts, it may be attached to the runners.
(13) The entire scaffold shall be tied to and securely braced against the building at intervals not to exceed 30 feet horizontally and 26 feet vertically.
(14) Guardrails not less than 2×4 inches or the equivalent and not less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1×4-inch lumber or equivalent, and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(d) Tubular welded frame scaffolds. (1) Metal tubular frame scaffolds, including accessories such as braces, brackets, trusses, screw legs, ladders, etc., shall be designed and proved to safely support four times the maximum intended load.
(2) Spacing of panels or frames shall be consistent with the loads imposed.
(3) Scaffolds shall be properly braced by cross bracing or diagonal braces, or both, for securing vertical members together laterally, and the cross braces shall be of such length as will automatically square and aline vertical members so that the erected scaffold is always plumb, square, and rigid. All brace connections shall be made secure.
(4) Scaffold legs shall be set on adjustable bases or plain bases placed on mud sills or other foundations adequate to support the maximum intended load.
(5) The frames shall be placed one on top of the other with coupling or stacking pins to provide proper vertical alinement of the legs.
(6) Where uplift may occur, panels shall be locked together vertically by pins or other equivalent suitable means.
(7) Guardrails not less than 2 × 4 inches or the equivalent and not less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1- × 4-inch lumber or equivalent, and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(8) All tubular metal scaffolds shall be constructed and erected to support four times the maximum intended loads.
(9) To prevent movement, the scaffold shall be secured to the building or structure at intervals not to exceed 30 feet horizontally and 26 feet vertically.
(10) Maximum permissible spans of planking shall be in conformity with paragraph (a)(9) of this section.
(11) Drawings and specifications for all frame scaffolds over 125 feet in height above the base plates shall be designed by a registered professional engineer and copies made available to the employer and for inspection purposes.
(12) All tubular welded frame scaffolds shall be erected by competent and experienced personnel.
(13) Frames and accessories for scaffolds shall be maintained in good repair and every defect, unsafe condition, or noncompliance with this section shall be immediately corrected before further use of the scaffold. Any broken, bent, excessively rusted, altered, or otherwise structurally damaged frames or accessories shall not be used.
(14) Periodic inspections shall be made of all welded frames and accessories, and any maintenance, including painting, or minor corrections authorized by the manufacturer, shall be made before further use.
(e) Outrigger scaffolds. (1) Outrigger beams shall extend not more than 6 feet beyond the face of the building. The inboard end of outrigger beams, measured from the fulcrum point to the extreme point of support, shall be not less than one and one-half times the outboard end in length. The beams shall rest on edge, the sides shall be plumb, and the edges shall be horizontal. The fulcrum point of the beam shall rest on a secure bearing at least 6 inches in each horizontal dimension. The beam shall be secured in place against movement and shall be securely braced at the fulcrum point against tipping.
(2) The inboard ends of outrigger beams shall be securely supported either by means of struts bearing against sills in contact with the overhead beams or ceiling, or by means of tension members secured to the floor joists underfoot, or by both if necessary. The inboard ends of outrigger beams shall be secured against tipping and the entire supporting structure shall be securely braced in both directions to prevent any horizontal movement.
(3) Unless outrigger scaffolds are designed by a licensed professional engineer, they shall be constructed and erected in accordance with table D–16. Outrigger scaffolds designed by a registered professional engineer shall be constructed and erected in accordance with such design. A copy of the detailed drawings and specifications showing the sizes and spacing of members shall be kept on the job.
(4) Planking shall be laid tight and shall extend to within 3 inches of the building wall. Planking shall be nailed or bolted to outriggers.
(5) Where there is danger of material falling from the scaffold, a wire mesh or other enclosure shall be provided between the guardrail and the toeboard.
(6) Where additional working levels are required to be supported by the outrigger method, the plans and specifications of the outrigger and scaffolding structure shall be designed by a registered professional engineer.
(f) Masons' adjustable multiple-point suspension scaffolds. (1) The scaffold shall be capable of sustaining a working load of 50 pounds per square foot and shall not be loaded in excess of that figure.
(2) The scaffold shall be provided with hoisting machines that meet the requirements of a nationally recognized testing laboratory. Refer to §1910.7 for definition of nationally recognized testing laboratory.
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Table D-16_Minimum Nominal Size and Maximum Spacing of Members of Outrigger Scaffolds------------------------------------------------------------------------ Light duty Medium duty------------------------------------------------------------------------Maximum scaffold load........... 25 p.s.f.......... 50 p.s.f.Outrigger size.................. 2x10 in........... 3x10 in.Maximum outrigger spacing....... 10 ft 0 in........ 6 ft 0 in.Planking........................ 2x9 in............ 2x9 in.Guardrail....................... 2x4 in............ 2x4 in.Guardrail uprights.............. 2x4 in............ 2x4 in.Toeboards (minimum)............. 4 in.............. 4 in.------------------------------------------------------------------------
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(3) The platform shall be supported by wire ropes in conformity with paragraph (a)(22) of this section, suspended from overhead outrigger beams.
(4) The scaffold outrigger beams shall consist of structural metal securely fastened or anchored to the frame or floor system of the building or structure.
(5) Each outrigger beam shall be equivalent in strength to at least a standard 7-inch, 15.3-pound steel I-beam, be at least 15 feet long, and shall not project more than 6 feet 6 inches beyond the bearing point.
(6) Where the overhang exceeds 6 feet 6 inches, outrigger beams shall be composed of stronger beams or multiple beams and be installed in accordance with approved designs and instructions.
(7) If channel iron outrigger beams are used in place of I-beams, they shall be securely fastened together with the flanges turned out.
(8) All outrigger beams shall be set and maintained with their webs into vertical position.
(9) A stop bolt shall be placed at each end of every outrigger beam.
(10) The outrigger beam shall rest on suitable wood-bearing blocks.
(11) All parts of the scaffold such as bolts, nuts, fittings, clamps, wire rope, and outrigger beams and their fastenings, shall be maintained in sound and good working condition and shall be inspected before each installation and periodically thereafter.
(12) The free end of the suspension wire ropes shall be equipped with proper size thimbles and be secured by splicing or other equivalent means. The running ends shall be securely attached to the hoisting drum and at least four turns of rope shall at all times remain on the drum.
(13) Where a single outrigger beam is used, the steel shackles or clevises with which the wire ropes are attached to the outrigger beams shall be placed directly over the hoisting drums.
(14) The scaffold platform shall be equivalent in strength to at least 2-inch planking. (For maximum planking spans see paragraph (a)(9) of this section.)
(15) Guardrails not less than 2 × 4 inches or the equivalent and not less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1 × 4-inch lumber or equivalent, and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(16) Overhead protection shall be provided on the scaffold, not more than 9 feet above the platform, consisting of 2-inch planking or material of equivalent strength laid tight, when men are at work on the scaffold and an overhead hazard exists.
(17) Each scaffold shall be installed or relocated in accordance with designs and instructions, of a registered professional engineer, and supervised by a competent, designated person.
(g) Two-point suspension scaffolds (swinging scaffolds). (1) Two-point suspension scaffold platforms shall be not less than 20 inches no more than 36 inches wide overall. The platform shall be securely fastened to the hangers by U-bolts or by other equivalent means.
(2) The hangers of two-point suspension scaffolds shall be made of wrought iron, mild steel, or other equivalent material having a cross-sectional area capable of sustaining four times the maximum intended load, and shall be designed with a support for guardrail, intermediate rail, and toeboard.
(3) When hoisting machines are used on two-point suspension scaffolds, such machines shall be of a design tested and approved by a nationally recognized testing laboratory. Refer to §1910.7 for definition of nationally recognized testing laboratory.
(4) The roof irons or hooks shall be of wrought iron, mild steel, or other equivalent material of proper size and design, securely installed and anchored. Tie-backs of three-fourth inch manila rope or the equivalent shall serve as a secondary means of anchorage, installed at right angles to the face of the building whenever possible and secured to a structurally sound portion of the building.
(5) Guardrails not less than 2 × 4 inches or the equivalent and not less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1- × 4-inch lumber or equivalent, and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(6) Two-point suspension scaffolds shall be suspended by wire or fiber ropes. Wire and fiber ropes shall conform to paragraph (a)(22) of this section.
(7) The blocks for fiber ropes shall be of standard 6-inch size, consisting of at least one double and one single block. The sheaves of all blocks shall fit the size of rope used.
(8) All wire ropes, fiber ropes, slings, hangers, platforms, and other supporting parts shall be inspected before every installation. Periodic inspections shall be made while the scaffold is in use.
(9) On suspension scaffolds designed for a working load of 500 pounds no more than two men shall be permitted to work at one time. On suspension scaffolds with a working load of 750 pounds, no more than three men shall be permitted to work at one time. Each workman shall be protected by a safety lifebelt attached to a lifeline. The lifeline shall be securely attached to substantial members of the structure (not scaffold), or to securely rigged lines, which will safely suspend the workman in case of a fall.
(10) Where acid solutions are used, fiber ropes are not permitted unless acid-proof.
(11) Two-point suspension scaffolds shall be securely lashed to the building or structure to prevent them from swaying. Window cleaners' anchors shall not be used for this purpose.
(12) The platform of every two-point suspension scaffold shall be one of the following types:
(i) The side stringer of ladder-type platforms shall be clear straight-grained spruce or materials of equivalent strength and durability. The rungs shall be of straight-grained oak, ash, or hickory, at least 11/8 inch in diameter, with seven-eighth inch tenons mortised into the side stringers at least seven-eighth inch. The stringers shall be tied together with the tie rods not less than one-quarter inch in diameter, passing through the stringers and riveted up tight against washers on both ends. The flooring strips shall be spaced not more than five-eighth inch apart except at the side rails where the space may be 1 inch. Ladder-type platforms shall be constructed in accordance with table D–17.
(ii) Plank-type platforms shall be composed of not less than nominal 2×8-inch unspliced planks, properly cleated together on the underside starting 6 inches from each end; intervals in between shall not exceed 4 feet. The plank-type platform shall not extend beyond the hangers more than 18 inches. A bar or other effective means shall be securely fastened to the platform at each end to prevent its slipping off the hanger. The span between hangers for plank-type platforms shall not exceed 10 feet.
(iii) Beam platforms shall have side stringers of lumber not less than 2×6 inches set on edge. The span between hangers shall not exceed 12 feet when beam platforms are used. The flooring shall be supported on 2- and 6-inch crossbeams, laid flat and set into the upper edge of the stringers with a snug fit, at intervals of not more than 4 feet, securely nailed in place. The flooring shall be of 1×6inch material properly nailed. Floorboards shall not be spaced more than one-half inch apart.
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Table D-17_Schedule for Ladder-Type Platforms---------------------------------------------------------------------------------------------------------------- Length of platform (feet) ----------------------------------------------------------- 14 & 18 & 22 & 28 & 12 16 20 24 30----------------------------------------------------------------------------------------------------------------Side stringers, minimum cross section (finished sizes): At ends (in.)..................................... 1\3/4\x2\3/ 1\3/4\x2\3/ 1\3/4\x3 1\3/4\x3 1\3/4\x3\1/ 4\ 4\ 2\ At middle (in.)................................... 1\3/4\x3\3/ 1\3/4\x3\3/ 1\3/4\x4 1\3/4\x4\1/ 1\3/4\x5 4\ 4\ 4\Reinforcing strip (minimum) \1\..................... .......... .......... .......... .......... ..........Rungs \2\........................................... .......... .......... .......... .......... ..........Tie rods: Number (minimum).................................. 3 4 4 5 6 Diameter (minimum)................................ \1/4\ in \1/4\ in \1/4\ in \1/4\ in \1/4\ in.Flooring, minimum finished size (in.)............... \1/2\x2\3/ \1/2\x2\3/ \1/2\x2\3/ \1/2\x\3/ \1/2\x2\3/ 4\ 4\ 4\ 4\ 4\----------------------------------------------------------------------------------------------------------------\1\ A \1/8\x\7/8\-in. steel reinforcing strip or its equivalent shall be attached to the side or underside full length.\2\ Rungs shall be 1\1/8\-in. minimum, diameter with at least \7/8\-in. diameter tenons, and the maximum spacing shall be 12 in. center to center.
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(h) Stone setters' adjustable multiple-point suspension scaffolds. (1) The scaffold shall be capable of sustaining a working load of 25 pounds per square foot and shall not be overloaded. Scaffolds shall not be used for storage of stone or other heavy materials.
(2) The hoisting machine and its supports shall be of a type tested and listed by a nationally recognized testing laboratory. Refer to §1910.399(a)(77) for definition of listed, and §1910.7 for nationally recognized testing laboratory.
(3) The platform shall be securely fastened to the hangers by U-bolts or other equivalent means.
(4) The scaffold unit shall be suspended from metal outriggers, iron brackets, wire rope slings, or iron hooks which will safely support the maximum intended load.
(5) Outriggers when used shall be set with their webs in a vertical position, securely anchored to the building or structure and provided with stop bolts at each end.
(6) The scaffold shall be supported by wire rope conforming with paragraph (a)(22) of this section, suspended from overhead supports.
(7) The free ends of the suspension wire ropes shall be equipped with proper size thimbles, secured by splicing or other equivalent means. The running ends shall be securely attached to the hoisting drum and at least four turns of rope shall remain on the drum at all times.
(8) Guardrails not less than 2 by 4 inches or the equivalent and not less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1- by 4-inch lumber or equivalent, and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(9) When two or more scaffolds are used on a building or structure they shall not be bridged one to the other but shall be maintained at even height with platforms butting closely.
(10) Each scaffold shall be installed or relocated in accordance with designs and instructions of a registered professional engineer, and such installation or relocation shall be supervised by a competent designated person.
(i) Single-point adjustable suspension scaffolds. (1) The scaffolding, including power units or manually operated winches, shall be a type tested and listed by a nationally recognized testing laboratory. Refer to §1910.399(a)(77) for definition of listed, and §1910.7 for nationally recognized testing laboratory.
(2) [Reserved]
(3) All power-operated gears and brakes shall be enclosed.
(4) In addition to the normal operating brake, all-power driven units must have an emergency brake which engages automatically when the normal speed of descent is exceeded.
(5) Guards, mid-rails, and toeboards shall completely enclose the cage or basket. Guardrails shall be no less than 2 by 4 inches or the equivalent installed no less than 36 inches nor more than 42 inches above the platform. Mid-rails shall be 1 by 6 inches or the equivalent, installed equidistant between the guardrail and the platform. Toeboards shall be a minimum of 4 inches in height.
(6) The hoisting machines, cables, and equipment shall be regularly serviced and inspected after each installation and every 30 days thereafter.
(7) The units may be combined to form a two-point suspension scaffold. Such scaffold shall comply with paragraph (g) of this section.
(8) The supporting cable shall be straight for its entire length, and the operator shall not sway the basket and fix the cable to any intermediate points to change his original path of travel.
(9) Equipment shall be maintained and used in accordance with the manufacturers' instructions.
(10) Suspension methods shall conform to applicable provisions of paragraphs (f) and (g) of this section.
(j) Boatswain's chairs. (1) The chair seat shall be not less than 12 by 24 inches, and of 1-inch thickness. The seat shall be reinforced on the underside to prevent the board from splitting.
(2) The two fiber rope seat slings shall be of 5/8-inch diameter, reeved through the four seat holes so as to cross each other on the underside of the seat.
(3) Seat slings shall be of at least 3/8-inch wire rope when a workman is conducting a heat producing process such as gas or arc welding.
(4) The workman shall be protected by a safety life belt attached to a lifeline. The lifeline shall be securely attached to substantial members of the structure (not scaffold), or to securely rigged lines, which will safely suspend the worker in case of a fall.
(5) The tackle shall consist of correct size ball bearing or bushed blocks and properly spliced 5/8-inch diameter first-grade manila rope.
(6) The roof irons, hooks, or the object to which the tackle is anchored shall be securely installed. Tiebacks when used shall be installed at right angles to the face of the building and securely fastened to a chimney.
(k) Carpenters' bracket scaffolds. (1) The brackets shall consist of a triangular wood frame not less than 2 by 3 inches in cross section, or of metal of equivalent strength. Each member shall be properly fitted and securely joined.
(2) Each bracket shall be attached to the structure by means of one of the following:
(i) A bolt no less than five-eighths inch in diameter which shall extend through the inside of the building wall.
(ii) A metal stud attachment device.
(iii) Welding to steel tanks.
(iv) Hooking over a well-secured and adequately strong supporting member.
The brackets shall be spaced no more than 10 feet apart.
(3) No more than two persons shall occupy any given 10 feet of a bracket scaffold at any one time. Tools and materials shall not exceed 75 pounds in addition to the occupancy.
(4) The platform shall consist of not less than two 2- by 9-inch nominal size planks extending not more than 18 inches or less than 6 inches beyond each end support.
(5) Guardrails not less than 2 by 4 inches or the equivalent and not less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1- by 4-inch lumber or equivalent, and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(l) Bricklayers' square scaffolds. (1) The squares shall not exceed 5 feet in width and 5 feet in height.
(2) Members shall be not less than those specified in Table D–18.
(3) The squares shall be reinforced on both sides of each corner with 1- by 6-inch gusset pieces. They shall also have braces 1 by 8 inches on both sides running from center to center of each member, or other means to secure equivalent strength and rigidity.
(4) The squares shall be set not more than 5 feet apart for medium duty scaffolds, and not more than 8 feet apart for light duty scaffolds. Bracing 1×8 inches, extending from the bottom of each square to the top of the next square, shall be provided on both front and rear sides of the scaffold.
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Table D-18_Minimum Dimensions for Bricklayers' Square Scaffold Members------------------------------------------------------------------------ Members Dimensions (inches)------------------------------------------------------------------------Bearers or horizontal members.............. 2 by 6.Legs....................................... 2 by 6.Braces at corners.......................... 1 by 6.Braces diagonally from center frame........ 1 by 8.------------------------------------------------------------------------
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(5) Platform planks shall be at least 2- by 9-inch nominal size. The ends of the planks shall overlap the bearers of the squares and each plank shall be supported by not less than three squares.
(6) Bricklayers' square scaffolds shall not exceed three tiers in height and shall be so constructed and arranged that one square shall rest directly above the other. The upper tiers shall stand on a continuous row of planks laid across the next lower tier and be nailed down or otherwise secured to prevent displacement.
(7) Scaffolds shall be level and set upon a firm foundation.
(m) Horse scaffolds. (1) Horse scaffolds shall not be constructed or arranged more than two tiers or 10 feet in height.
(2) The members of the horses shall be not less than those specified in Table D–19.
(3) Horses shall be spaced not more than 5 feet for medium duty and not more than 8 feet for light duty.
(4) When arranged in tiers, each horse shall be placed directly over the horse in the tier below.
(5) On all scaffolds arranged in tiers, the legs shall be nailed down to the planks to prevent displacement or thrust and each tier shall be substantially cross braced.
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Table D-19_Minimum Dimensions for Horse Scaffold Members------------------------------------------------------------------------ Members Dimensions (inches)------------------------------------------------------------------------Horizontal members or bearers.............. 3 by 4.Legs....................................... 1\1/4\ by 4\1/2\.Longitudinal brace between legs............ 1 by 6.Gusset brace at top of legs................ 1 by 8.Half diagonal braces....................... 1\1/4\ by 4\1/2\.------------------------------------------------------------------------
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(6) Horses or parts which have become weak or defective shall not be used.
(7) Guardrails not less than 2 by 4 inches or the equivalent and not less than 36 inches or more than 42 inches high with a mid-rail, when required, of 1- by 4-inch lumber or equivalent and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(n) Needle beam scaffold. (1) Wood needle beams shall be in accordance with paragraph (a) (5) and (9) of this section, and shall be not less than 4 by 6 inches in size, with the greater dimension placed in a vertical direction. Metal beams or the equivalent conforming to paragraph (a) (4) and (8) of this section may be used.
(2) Ropes or hangers shall be provided for supports. The span between supports on the needle beam shall not exceed 10 feet for 4- by 6-inch timbers. Rope supports shall be equivalent in strength to 1-inch diameter first-grade manila rope.
(3) The ropes shall be attached to the needle beams by a scaffold hitch or a properly made eye splice. The loose end of the rope shall be tied by a bowline knot or by a round turn and one-half hitch.
(4) The platform span between the needle beams shall not exceed 8 feet when using 2-inch scaffold plank. For spans greater than 8 feet, platforms shall be designed based on design requirements for the special span. The overhang of each end of the platform planks shall be not less than 1 foot and not more than 18 inches.
(5) When one needle beam is higher than the other or when the platform is not level the platform shall be secured against slipping.
(6) All unattached tools, bolts, and nuts used on needle beam scaffolds shall be kept in suitable containers.
(7) One end of a needle beam scaffold may be supported by a permanent structural member conforming to paragraphs (a) (4) and (8) of this section.
(8) Each man working on a needle beam scaffold 20 feet or more above the ground or floor and working with both hands, shall be protected by a safety life belt attached to a lifeline. The lifeline shall be securely attached to substantial members of the structure (not scaffold), or to securely rigged lines, which will safely suspend the workman in case of a fall.
(o) Plasterers', decorators', and large area scaffolds. (1) Plasterers', decorators', lathers', and ceiling workers' inside scaffolds shall be constructed in accordance with the general requirements set forth for independent wood pole scaffolds.
(2) Guardrails not less than 2 by 4 inches or the equivalent and not less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1- by 4-inch lumber or equivalent, and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(3) All platform planks shall be laid with the edges close together.
(4) When independent pole scaffold platforms are erected in sections, such sections shall be provided with connecting runways equipped with substantial guardrails.
(p) Interior hung scaffolds.
(1) [Reserved]
(2) The suspended steel wire rope shall conform to paragraph (a)(22) of this section. Wire may be used providing the strength requirements of paragraph (a)(22) of this section are met.
(3) For hanging wood scaffolds, the following minimum nominal size material is recommended:
(i) Supporting bearers 2 by 9 inches on edge.
(ii) Planking 2 by 9 inches or 2 by 10 inches, with maximum span 7 feet for heavy duty and 10 feet for light duty or medium duty.
(4) Steel tube and coupler members may be used for hanging scaffolds with both types of scaffold designed to sustain a uniform distributed working load up to heavy duty scaffold loads with a safety factor of four.
(5) When a hanging scaffold is supported by means of wire rope, such wire rope shall be wrapped at least twice around the supporting members and twice around the bearers of the scaffold, with each end of the wire rope secured by at least three standard wire-rope clips.
(6) All overhead supporting members shall be inspected and checked for strength before the scaffold is erected.
(7) Guardrails not less than 2 by 4 inches or the equivalent and not less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1- by 4-inch lumber or equivalent, and toeboards, shall be installed at all open sides on all scaffolds more than 10 feet above the ground or floor. Toeboards shall be a minimum of 4 inches in height. Wire mesh shall be installed in accordance with paragraph (a)(17) of this section.
(q) Ladder-jack scaffolds. (1) All ladder-jack scaffolds shall be limited to light duty and shall not exceed a height of 20 feet above the floor or ground.
(2) All ladders used in connection with ladder-jack scaffolds shall be heavy-duty ladders and shall be designed and constructed in accordance with §1910.25 and §1910.26.
(3) The ladder jack shall be so designed and constructed that it will bear on the side rails in addition to the ladder rungs, or if bearing on rungs only, the bearing area shall be at least 10 inches on each rung.
(4) Ladders used in conjunction with ladder jacks shall be so placed, fastened, held, or equipped with devices so as to prevent slipping.
(5) The wood platform planks shall be not less than 2 inches nominal in thickness. Both metal and wood platform planks shall overlap the bearing surface not less than 12 inches. The span between supports for wood shall not exceed 8 feet. Platform width shall be not less than 18 inches.
(6) Not more than two persons shall occupy any given 8 feet of any ladder-jack scaffold at any one time.
(r) Window-jack scaffolds. (1) Window-jack scaffolds shall be used only for the purpose of working at the window opening through which the jack is placed.
(2) Window jacks shall not be used to support planks placed between one window jack and another or for other elements of scaffolding.
(3) Window-jack scaffolds shall be provided with suitable guardrails unless safety belts with lifelines are attached and provided for the workman. Window-jack scaffolds shall be used by one man only.
(s) Roofing brackets. (1) Roofing brackets shall be constructed to fit the pitch of the roof.
(2) Brackets shall be secured in place by nailing in addition to the pointed metal projections. The nails shall be driven full length into the roof. When rope supports are used, they shall consist of first-grade manila of at least three-quarter-inch diameter, or equivalent.
(3) A substantial catch platform shall be installed below the working area of roofs more than 20 feet from the ground to eaves with a slope greater than 3 inches in 12 inches without a parapet. In width the platform shall extend 2 feet beyond the projection of the eaves and shall be provided with a safety rail, mid-rail, and toeboard. This provision shall not apply where employees engaged in work upon such roofs are protected by a safety belt attached to a lifeline.
(t) Crawling boards or chicken ladders. (1) Crawling boards shall be not less than 10 inches wide and 1 inch thick, having cleats 1×11/2 inches. The cleats shall be equal in length to the width of the board and spaced at equal intervals not to exceed 24 inches. Nails shall be driven through and clinched on the underside. The crawling board shall extend from the ridge pole to the eaves when used in connection with roof construction, repair, or maintenance.
(2) A firmly fastened lifeline of at least three-quarter-inch rope shall be strung beside each crawling board for a handhold.
(3) Crawling boards shall be secured to the roof by means of adequate ridge hooks or equivalent effective means.
(u) Float or ship scaffolds. (1) Float or ship scaffolds shall support not more than three men and a few light tools, such as those needed for riveting, bolting, and welding. They shall be constructed in accordance with paragraphs (u) (2) through (6) of this section, unless substitute designs and materials provide equivalent strength, stability, and safety.
(2) The platform shall be not less than 3 feet wide and 6 feet long, made of three-quarter-inch plywood, equivalent to American Plywood Association Grade B-B, Group I, Exterior.
(3) Under the platform, there shall be two supporting bearers made from 2×4-inch, or 1×10-inch rough, selected lumber, or better. They shall be free of knots or other flaws and project 6 inches beyond the platform on both sides. The ends of the platform shall extend about 6 inches beyond the outer edges of the bearers. Each bearer shall be securely fastened to the platform.
(4) An edging of wood not less than 3/4×11/2 inches, or equivalent, shall be placed around all sides of the platform to prevent tools from rolling off.
(5) Supporting ropes shall be 1-inch diameter manila rope or equivalent, free from deterioration, chemical damage, flaws, or other imperfections. Rope connections shall be such that the platform cannot shift or slip. If two ropes are used with each float, each of the two supporting ropes shall be hitched around one end of a bearer and pass under the platforms to the other end of the bearer where it is hitched again, leaving sufficient rope at each end for the supporting ties.
(6) Each workman shall be protected by a safety lifebelt attached to a lifeline. The lifeline shall be securely attached to substantial members of the structure (not scaffold), or to securely rigged lines, which will safely suspend the workman in case of a fall.
(v) Scope. This section establishes safety requirements for the construction, operation, maintenance, and use of scaffolds used in the maintenance of buildings and structures.
[39 FR 23502, June 27, 1974, as amended at 43 FR 49746, Oct. 24, 1978; 49 FR 5321, Feb. 10, 1984; 53 FR 12121, Apr. 12, 1988] § 1910.29 Manually propelled mobile ladder stands and scaffolds (towers).
(a) General requirements—(1) Application. This section is intended to prescribe rules and requirements for the design, construction, and use of mobile work platforms (including ladder stands but not including aerial ladders) and rolling (mobile) scaffolds (towers). This standard is promulgated to aid in providing for the safety of life, limb, and property, by establishing minimum standards for structural design requirements and for the use of mobile work platforms and towers.
(2) Working loads. (i) Work platforms and scaffolds shall be capable of carrying the design load under varying circumstances depending upon the conditions of use. Therefore, all parts and appurtenances necessary for their safe and efficient utilization must be integral parts of the design.
(ii) Specific design and construction requirements are not a part of this section because of the wide variety of materials and design possibilities. However, the design shall be such as to produce a mobile ladder stand or scaffold that will safely sustain the specified loads. The material selected shall be of sufficient strength to meet the test requirements and shall be protected against corrosion or deterioration.
(a) The design working load of ladder stands shall be calculated on the basis of one or more 200-pound persons together with 50 pounds of equipment each.
(b) The design load of all scaffolds shall be calculated on the basis of:
Light—Designed and constructed to carry a working load of 25 pounds per square foot.
Medium—Designed and constructed to carry a working load of 50 pounds per square foot.
Heavy—Designed and constructed to carry a working load of 75 pounds per square foot.
All ladder stands and scaffolds shall be capable of supporting at least four times the design working load.
(iii) The materials used in mobile ladder stands and scaffolds shall be of standard manufacture and conform to standard specifications of strength, dimensions, and weights, and shall be selected to safely support the design working load.
(iv) Nails, bolts, or other fasteners used in the construction of ladders, scaffolds, and towers shall be of adequate size and in sufficient numbers at each connection to develop the designed strength of the unit. Nails shall be driven full length. (All nails should be immediately withdrawn from dismantled lumber.)
(v) All exposed surfaces shall be free from sharp edges, burrs or other safety hazards.
(3) Work levels. (i) The maximum work level height shall not exceed four (4) times the minimum or least base dimensions of any mobile ladder stand or scaffold. Where the basic mobile unit does not meet this requirement, suitable outrigger frames shall be employed to achieve this least base dimension, or provisions shall be made to guy or brace the unit against tipping.
(ii) The minimum platform width for any work level shall not be less than 20 inches for mobile scaffolds (towers). Ladder stands shall have a minimum step width of 16 inches.
(iii) The supporting structure for the work level shall be rigidly braced, using adequate cross bracing or diagonal bracing with rigid platforms at each work level.
(iv) The steps of ladder stands shall be fabricated from slip resistant treads.
(v) The work level platform of scaffolds (towers) shall be of wood, aluminum, or plywood planking, steel or expanded metal, for the full width of the scaffold, except for necessary openings. Work platforms shall be secured in place. All planking shall be 2-inch (nominal) scaffold grade minimum 1,500 f. (stress grade) construction grade lumber or equivalent.
(vi) All scaffold work levels 10 feet or higher above the ground or floor shall have a standard (4-inch nominal) toeboard.
(vii) All work levels 10 feet or higher above the ground or floor shall have a guardrail of 2- by 4-inch nominal or the equivalent installed no less than 36 inches or more than 42 inches high, with a mid-rail, when required, of 1- by 4-inch nominal lumber or equivalent.
(viii) A climbing ladder or stairway shall be provided for proper access and egress, and shall be affixed or built into the scaffold and so located that its use will not have a tendency to tip the scaffold. A landing platform shall be provided at intervals not to exceed 30 feet.
(4) Wheels or casters. (i) Wheels or casters shall be properly designed for strength and dimensions to support four (4) times the design working load.
(ii) All scaffold casters shall be provided with a positive wheel and/or swivel lock to prevent movement. Ladder stands shall have at least two (2) of the four (4) casters and shall be of the swivel type.
(iii) Where leveling of the elevated work platform is required, screw jacks or other suitable means for adjusting the height shall be provided in the base section of each mobile unit.
(b) Mobile tubular welded frame scaffolds—(1) General. Units shall be designed to comply with the requirements of paragraph (a) of this section.
(2) Bracing. Scaffolds shall be properly braced by cross braces and/or diagonal braces for securing vertical members together laterally. The cross braces shall be of a length that will automatically square and align vertical members so the erected scaffold is always plumb, square, and rigid.
(3) Spacing. Spacing of panels or frames shall be consistent with the loads imposed. The frames shall be placed one on top of the other with coupling or stacking pins to provide proper vertical alignment of the legs.
(4) Locking. Where uplift may occur, panels shall be locked together vertically by pins or other equivalent means.
(5) Erection. Only the manufacturer of a scaffold or his qualified designated agent shall be permitted to erect or supervise the erection of scaffolds exceeding 50 feet in height above the base, unless such structure is approved in writing by a registered professional engineer, or erected in accordance with instructions furnished by the manufacturer.
(c) Mobile tubular welded sectional folding scaffolds—(1) General. Units including sectional stairway and sectional ladder scaffolds shall be designed to comply with the requirements of paragraph (a) of this section.
(2) Stairway. An integral stairway and work platform shall be incorporated into the structure of each sectional folding stairway scaffold.
(3) Bracing. An integral set of pivoting and hinged folding diagonal and horizontal braces and a detachable work platform shall be incorporated into the structure of each sectional folding ladder scaffold.
(4) Sectional folding stairway scaffolds. Sectional folding stairway scaffolds shall be designed as medium duty scaffolds except for high clearance. These special base sections shall be designed as light duty scaffolds. When upper sectional folding stairway scaffolds are used with a special high clearance base, the load capacity of the entire scaffold shall be reduced accordingly. The width of a sectional folding stairway scaffold shall not exceed 41/2 feet. The maximum length of a sectional folding stairway scaffold shall not exceed 6 feet.
(5) Sectional folding ladder scaffolds. Sectional folding ladder scaffolds shall be designed as light duty scaffolds including special base (open end) sections which are designed for high clearance. For certain special applications the six-foot (6') folding ladder scaffolds, except for special high clearance base sections, shall be designed for use as medium duty scaffolds. The width of a sectional folding ladder scaffold shall not exceed 41/2 feet. The maximum length of a sectional folding ladder scaffold shall not exceed 6 feet 6 inches for a six-foot (6′) long unit, 8 feet 6 inches for an eight-foot (8′) unit or 10 feet 6 inches for a ten-foot (10′) long unit.
(6) End frames. The end frames of sectional ladder and stairway scaffolds shall be designed so that the horizontal bearers provide supports for multiple planking levels.
(7) Erection. Only the manufacturer of the scaffold or his qualified designated agent shall be permitted to erect or supervise the erection of scaffolds exceeding 50 feet in height above the base, unless such structure is approved in writing by a licensed professional engineer, or erected in accordance with instructions furnished by the manufacturer.
(d) Mobile tube and coupler scaffolds—(1) Design. Units shall be designed to comply with the applicable requirements of paragraph (a) of this section.
(2) Material. The material used for the couplers shall be of a structural type, such as a drop-forged steel, malleable iron or structural grade aluminum. The use of gray cast iron is prohibited.
(3) Erection. Only the manufacturer of the scaffold or his qualified designated agent shall be permitted to erect or supervise the erection of scaffolds exceeding 50 feet in height above the base, unless such structure is approved in writing by a licensed professional engineer, or erected in accordance with instructions furnished by the manufacturer.
(e) Mobile work platforms—(1) Design. Units shall be designed for the use intended and shall comply with the requirements of paragraph (a) of this section.
(2) Base width. The minimum width of the base of mobile work platforms shall not be less than 20 inches.
(3) Bracing. Adequate rigid diagonal bracing to vertical members shall be provided.
(f) Mobile ladder stands—(1) Design. Units shall comply with applicable requirements of paragraph (a) of this section.
(2) Base width. The minimum base width shall conform to paragraph (a)(3)(i) of this section. The maximum length of the base section shall be the total length of combined steps and top assembly, measured horizontally, plus five-eighths inch per step of rise.
(3) Steps. Steps shall be uniformly spaced, and sloped, with a rise of not less than nine (9) inches, nor more than ten (10) inches, and a depth of not less seven (7) inches. The slope of the steps section shall be a minimum of fifty-five (55) degrees and a maximum of sixty (60) degrees measured from the horizontal.
(4) Handrails. (i) Units having more than five (5) steps or 60 inches vertical height to the top step shall be equipped with handrails.
(ii) Handrails shall be a minimum of 29 inches high. Measurements shall be taken vertically from the center of the step.
(5) Loading. The load (see paragraph (a)(2)(ii)(a) of this section) shall be applied uniformly to a 31/2 inches wide area front to back at the center of the width span with a safety factor of four (4). § 1910.30 Other working surfaces.
(a) Dockboards (bridge plates). (1) Portable and powered dockboards shall be strong enough to carry the load imposed on them.
(2) Portable dockboards shall be secured in position, either by being anchored or equipped with devices which will prevent their slipping.
(3) Powered dockboards shall be designed and constructed in accordance with Commercial Standard CS202–56 (1961) “Industrial Lifts and Hinged Loading Ramps published by the U.S. Department of Commerce, which is incorporated by reference as specified in §1910.6.
(4) Handholds, or other effective means, shall be provided on portable dockboards to permit safe handling.
(5) Positive protection shall be provided to prevent railroad cars from being moved while dockboards or bridge plates are in position.
(b) Forging machine area. (1) Machines shall be so located as to give (i) enough clearance between machines so that the movement of one operator will not interfere with the work of another, (ii) ample room for cleaning machines and handling the work, including material and scrap. The arrangement of machines shall be such that operators will not stand in aisles.
(2) Aisles shall be provided of sufficient width to permit the free movement of employees bringing and removing material. This aisle space is to be independent of working and storage space.
(3) Wood platforms used on the floor in front of machines shall be substantially constructed.
(c) Veneer machinery. (1) Sides of steam vats shall extend to a height of not less than 36 inches above the floor, working platform, or ground.
(2) Large steam vats divided into sections shall be provided with substantial walkways between sections. Each walkway shall be provided with a standard handrail on each exposed side. These handrails may be removable, if necessary.
(3) Covers shall be removed only from that portion of steaming vats on which men are working and a portable railing shall be placed at this point to protect the operators.
(4) Workmen shall not ride or step on logs in steam vats.
[39 FR 23502, June 27, 1974, as amended at 49 FR 5322, Feb. 10, 1984; 61 FR 9235, Mar. 7, 1996]
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