24 C.F.R. § 3280.610 Drainage systems.
Title 24 - Housing and Urban Development
(a) General. (1) Each fixture directly connected to the drainage system shall be installed with a water seal trap (§3280.606(a)). (2) The drainage system shall be designed to provide an adequate circulation of air in all piping with no danger of siphonage, aspiration, or forcing of trap seals under conditions of ordinary use. (b) Materials—(1) Pipe. Drainage piping shall be standard weight steel, wrought iron, brass, copper tube DWV, listed plastic, cast iron, or other listed or approved materials. (2) Fittings. Drainage fittings shall be recessed drainage pattern with smooth interior waterways of the same diameter as the piping and shall be of a material conforming to the type of piping used. Drainage fittings shall be designed to provide for a (i) Fittings for screw pipe shall be cast iron, malleable iron, brass, or listed plastic with standard pipe threads. (ii) Fittings for copper tubing shall be cast brass or wrought copper. (iii) Socket-type fittings for plastic piping shall comply with listed standards. (iv) Brass or bronze adaptor or wrought copper fittings shall be used to join copper tubing to threaded pipe. (c) Drain outlets. (1) Each manufactured home shall have only one drain outlet. (2) Clearance from drain outlet. The drain outlet shall be provided with a minimum clearance of 3 inches in any direction from all parts of the structure or appurtenances and with not less than 18 inches unrestricted clearance directly in front of the drain outlet. (3) Drain connector. The drain connector shall not be smaller than the piping to which it is connected and shall be equipped with a water-tight cap or plug matching the drain outlet. The cap or plug shall be permanently attached to the manufactured home or drain outlet. (4) The drain outlet and drain connector shall not be less than 3 inches inside diameter. (5) Preassembly of drain lines. Section(s) of the drain system, designed to be located underneath the home, are not required to be factory installed when the manufacturer designs the system for site assembly and also provides all materials and components, including piping, fittings, cement, supports, and instructions necessary for proper site installation. (d) Fixture connections. Drainage piping shall be provided with approved or listed inlet fittings for fixture connections, correctly located according to the size and type of fixture to be connected. (1) Water closet connection. The drain connection for each water closet shall be 3 inches minimum inside diameter and shall be fitted with an iron, brass, or listed plastic floor flange adaptor ring securely screwed, soldered or otherwise permanently attached to the drain piping, in an approved manner and securely fastened to the floor. (2) [Reserved] (e) Size of drainage piping—(1) Fixture load. Except as provided by §3280.611(d), drain pipe sizes shall be determined by the type of fixture and the total number connected to each drain. (i) A 1 (ii) A 2-inch minimum diameter piping shall be required for four or more fixtures individually vented. (iii) A 3-inch minimum diameter piping shall be required for water closets. (f) Wet-vented drainage system. Plumbing fixture traps may connect into a wet-vented drainage system which shall be designed and installed to accommodate the passage of air and waste in the same pipe. (1) Horizontal piping. All parts of a wet-vented drainage system, including the connected fixture drains, shall be horizontal except for wet-vented vertical risers which shall terminate with a 1 (2) Size. A wet-vented drain pipe shall be 2 inches minimum diameter and at least one pipe size larger than the largest connected trap or fixture drain. Not more than three fixtures may connect to a 2-inch diameter wet-vented drain system. (3) Length of trap arm. Fixture traps shall be located within the distance given in §3280.611(c)(5). Not more than one trap shall connect to a trap arm. (g) Offsets and branch fittings—(1) Changes in direction. Changes in direction of drainage piping shall be made by the appropriate use of approved or listed fittings, and shall be of the following angles: 11 (2) Horizontal to vertical. Horizontal drainage lines, connecting with a vertical pipe shall enter through 45-degree “Y” branches, 60-degree “Y” branches, long-turn “TY” branches, sanitary “T” branches, or other approved or listed fittings or combination of fittings having equivalent sweep. Fittings having more than one branch at the same level shall not be used, unless the fitting is constructed so that the discharge from any one branch cannot readily enter any other branch. However, a double sanitary “T” may be used when the drain line is increased not less than two pipe sizes. (3) Horizontal to horizontal and vertical to horizontal. Horizontal drainage lines connecting with other horizontal drainage lines or vertical drainage lines connected with horizontal drainage lines shall enter through 45-degree “Y” branches, long-turn “TY” branches, or other approved or listed fittings or combination of fittings having equivalent sweep. (h) Grade of horizontal drainage piping. Except for fixture connections on the inlet side of the trap, horizontal drainage piping shall be run in practical alignment and have a uniform grade of not less than [40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4586, Feb. 12, 1987; 58 FR 55015, Oct. 25, 1993]
Title 24: Housing and Urban Development
PART 3280—MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS
Subpart G—Plumbing Systems
§ 3280.610 Drainage systems.
