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Mobile home water heater (C) Daniel FriedmanHow to Inspect the Plumbing Systems of Mobile Homes, Double wides, Trailer homes

  • MOBILE HOME PLUMBING - CONTENTS: Mobile home plumbing system: fixtures, water supply, drainage, sewage system inspection guide. Common mobile home plumbing system defects at plumbing pipes, fixtures, water heaters, oil tanks, oil piping or gas piping. Safety and building codes for mobile homes. Mobile ome or doublewide septic tanks & systems.
  • POST a QUESTION or READ FAQs about mobile home & double-wide plumbing systems: inspection, diagnosis, repair, or replacement of mobile home plumbing
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How to Inspect Mobile Homes or Manufactured Housing for Plumbing System Defects:

Detailed mobile home, trailer or doublewide plumbing inspection procedures, defect lists, references to plumbing standards for mobile homes, trailers, double-wide home plumbing water supply & drain piping and oil or gas fuel piping.

Mobile home septic systems are also addressed.



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Doublewide, Mobile Home (Caravan) or Trailer Plumbing System Defects & Hazards

Mobile home water heater (C) Daniel FriedmanMobile home & manufactured home plumbing standards, codes, defects & repairs.

Article Contents:

Ver.4.0 - 04/25/07, updated through January 2018 - Steve Vermilye, New Paltz NY and Daniel Friedman, Poughkeepsie NY, Hudson Valley ASHI Chapter Seminar, Newburgh NY, January 4, 2000, NY Metro ASHI Fall 99 Seminar, Holiday Inn Crowne Plaza, White Plains NY, October 2, 1999. Our page top photo shows our associated Steve Vermilye inspecting an on-ground, tipping, heating oil tank at a mobile home occupied by farm workers in Ulster County, N.Y.

GENERAL PLUMBING - Comments for Mobile Home Inspectors

SUPPLY PIPING - Mobile Home Supply Piping Defects and Plastic or polybutylene water supply piping failures, leaks, and litigation

Freeze Protection Suggestions for Mobile Homes, Double-Wides and Trailers:

Wiring for heat tape on oil tank (C) Daniel Friedman

Trailer water entry (C) Daniel Friedman Trailer water entry (C) Daniel Friedman Plumbing below a mobile home subject to freezing (C) Daniel Friedman

DRAIN WASTE VENT - Mobile Home & Trailer Drain Waste Vent Piping Defects

Mobile home drain onto ground surface (C) Daniel Friedman Mobile home bathroom (C) Daniel Friedman Multiple repairs indicates freezing pipe history (C) Daniel Friedman

Our photo (below-left) illustrates an area of plumbing drain leaks below the sink in a doublewide home - rot destroyed the subfloor, invited carpenter ants into the structure, and soaked insulation.

Plumbing drains in mobile home, leaks, floor damage (C) Daniel Friedman Improper and non-functional tub controls and spout in a mobile home (C) Daniel Friedman


Leaky sink and mold in mobile home (C) Daniel Friedman Leaks at tub in mobile home (C) Daniel Friedman

MOBILE HOME & TRAILER or DOUBLE-Wide Heating FUEL SUPPLY Defects & Concerns, gas and oil piping

LP gank gas piping defects exposed to damage (C) Daniel Friedman


Warnings about using heat tapes on mobile home water or drain pipes or on heating oil lines

Mobile home oil tank (C) Daniel Friedman

Heat Tapes - use metal-braid shielded type connected to GFCI so if a short will trip. Heat tapes, especially the non-shielded types, short and start fires, especially if crossed over themselves or otherwise improperly installed.

Mobile home oil tank defects, problems, repairs

Oil tank fuel gage using a soft drink bottle (C) Daniel Friedman

WATER HEATER Defects & Safety Hazards in Mobile Homes, Trailers, Double-Wides

Multiple repairs indicates freezing pipe history (C) Daniel Friedman
Mobile home water heater (C) Daniel Friedman Mobile home water heater (C) Daniel Friedman Mobile home water heater (C) Daniel Friedman Mobile home water heater (C) Daniel Friedman

MOBILE HOME PLUMBING Fixture Defects

Manufactured / Mobile Home Plumbing Codes & Standards

PART 3280—MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS [PDF] Complete text of 24 CFR Part 3280 - MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS contains 10 subparts pertaining to General (data plate and certification contents and locations), Plans (dimensions, exits, etc), Fire Safety, Body and Frame, Testing, Thermal Protection, Heating/Cooling and venting systems, Electrical, and Transportation (axles, springs, drawbar). It's about 90 pages of regulations.

Excerpts from Subpart G - Plumbing Systems (§§ 3280.601 - 3280.612)

§3280.603 General requirements.

(a) Minimum requirements. Any plumbing system installed in a manufactured home shall conform, at least, with the provisions of this subpart.

(1) General. The plumbing system shall be of durable material, free from defective workmanship, and so designed and constructed as to give satisfactory service for a reasonable life expectancy.

(2) Conservation. Each water closet must not use more than 1.6 gallons of water per flush.

(3) Connection to drainage system. All plumbing, fixtures, drains, appurtenances, and appliances designed or used to receive or discharge liquid waste or sewage shall be connected to the manufactured home drainage system in a manner provided by this standard.

(4) Workmanship. All design, construction, and workmanship shall be in conformance with accepted engineering practices and shall be of such character as to secure the results sought to be obtained by this standard.

(5) Components. Plumbing materials, devices, fixtures, fittings, equipment, appliances, appurtenance, and accessories intended for use in or attached to a manufactured home shall conform to one of the applicable standards referenced in §3280.604. Where an applicable standard is not referenced, or an alternative recognized standard is utilized, the plumbing component shall be listed by a nationally recognized testing laboratory, inspection agency or other qualified organization as suitable for the intended use.

(6) Prohibited fittings and practices. (i) Drainage or vent piping shall not be drilled and tapped for the purpose of making connections.

(ii) Except as specifically provided elsewhere in this standard, vent pipes shall not be used as waste or drain pipes.

(iii) Fittings, connections, devices, or methods of installation that obstruct or retard the flow of sewage, or air in the drainage or venting systems in an amount greater than the normal frictional resistance to flow shall not be used unless their use is acceptable in this standard or their use is accepted as having a desirable and acceptable function of ultimate benefit to the proper and continued functioning of the plumbing system.

(iv) Cracks, holes, or other imperfections in materials shall not be concealed by welding, brazing, or soldering or by paint, wax, tar, or other leak­sealing or repairing agents.

(v) Piping, fixtures or equipment shall be located so as not to interfere with the normal use or with the normal operation and use of windows, doors or other required facilities.

(vi) Galvanized pipe shall not be bent or welded.

(7) Alignment of fittings. All valves, pipes, and fittings shall be installed in correct relationship to the direction of flow.

(b) Protective requirements.

(1) Cutting structural members. Structural members shall not be unnecessarily or carelessly weakened by cutting or notching.

(2) Exposed piping. All piping, pipe threads, hangers, and support exposed to the weather, water, mud, and road hazard, and subject to damage therefrom, shall be painted, coated, wrapped, or otherwise protected from deterioration.

(3) Road damage. Pipes, supports, drains, outlets, or drain hoses shall not extend or protrude in a manner where they could be unduly subjected to damage during transit.

(4) Freezing. All piping and fixtures subject to freezing temperatures shall be insulated or protected to prevent freezing, under normal occupancy. The manufacturer shall provide:

(i) Written installation instructions for the method(s) required for compliance to this section;

(ii) A statement in the installation instructions required by §3280.306(b), stating that if the heat tape or pipe heating cable is used, it must be listed for use with manufactured homes.

(iii) A receptacle outlet complying with §3280.806(d)(10).

(5) All piping, except the fixture trap, shall be designed to allow drainage.

(6) Rodent resistance. All exterior openings around piping and equipment shall be sealed to resist the entrance of rodents.

(7) Piping and electrical wiring shall not pass through the same holes in walls, floors or roofs. Plastic piping shall not be exposed to heat in excess of manufacturers recommendation or radiation from heat producing appliances.

[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 54383, Oct. 5, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended
at 58 FR 55012, Oct. 25, 1993; 78 FR 73985, Dec. 9, 2013]

§3280.605 Joints and connections.

(a) Tightness. Joints and connections in the plumbing system shall be gastight and watertight for the pressures required under testing procedures.

(b) Assembling of pipe. All joints and connections shall be correctly assembled for tightness. Pipe threads shall be fully engaged with the threads of the fitting. Plastic pipe and copper tubing shall be inserted to the full depth of the solder cup or welding sockets of each fitting. Pipe threads and slip joints shall not be wrapped with string, paper, putty, or similar fillers.

(c) Threaded joints. Threads for screw pipe and fittings shall conform to the approved or listed standard. Pipe ends shall be reamed out to size of bore. All burrs, chips, cutting oil and foreign matter shall be removed. Pipe joint cement or thread lubricant shall be of approved type and applied to male threads only.

(d) Solder joints. Solder joints for tubing shall be made with approved or listed solder type fittings. Surfaces to be soldered shall be cleaned bright. The joints shall be properly fluxed with noncorrosive paste type flux and, for manufactured homes to be connected to a public water system, made with solder having not more than 0.2 percent lead.

(e) Plastic pipe, fittings and joints. Plastic pipe and fittings shall be joined by installation methods recommended by the manufacturer or in accordance with the provisions of a recognized, approved, or listed standard.

(f) Union joints. Metal unions in water piping shall have metal­to­metal ground seats.

(g) Flared joints. Flared joints for soft­copper water tubing shall be made with approved or listed fittings. The tubing shall be expanded with a proper flaring tool.

(h) Cast iron soil pipe joints. Approved or listed cast iron pipe may be joined as follows:

(1) Approved or listed hub­less pipe and fittings must be permitted to be joined with listed couplings or adapters, per the manufacturer's recommendations.

(2) Hub and plain­end soil pipe may be joined by compression fittings per the manufacturer's recommendation

§3280.606 Traps and cleanouts.

(a) Traps—

(1) Traps required. Each plumbing fixture, except listed toilets, shall be separately trapped by approved water seal “P” traps. All traps shall be effectively vented.

(2) Combination Fixtures. For the purposes of drainage and ventilation requirements, a two­ or three­compartment sink, up to three single sinks, or up to three lavatories may be connected to one “P” trap and considered as a single fixture, so long as the sinks and lavatories are in the same room, have waste outlets not more than 30 inches apart, and have flood level rims at the same level. The “P” trap must be installed at the center fixture when three such fixtures are installed.

(3) Prohibited traps. A trap which depends for its seal upon concealed interior partitions shall not be used. Full “S” traps, bell traps, drum traps, crown­vented traps, and running traps are prohibited. Fixtures shall not be double­trapped.

(4) Material and design. Each trap shall be self­cleaning with a smooth and uniform interior waterway. Traps shall be manufactured of cast iron, cast brass, or drawn brass tubing of not less than No. 20 Brown and Sharpe gage, or approved or listed plastic, or other approved or listed material. Union joints for a trap shall be beaded to provide a shoulder for the union nut. Each trap shall have the manufacturer's name stamped or cast in the body of the trap, and each tubing trap shall show the gage of the tubing.

(5) Trap seal. Each “P” trap shall have a water seal of not less than 2 inches and not more than 4 inches and shall be set true to its seal.

(6) Size. Traps shall be not less than 1 1 ∕4 inches in diameter. A trap shall not be larger than the waste pipe to which it is connected.

(7) Location. Each trap shall be located as close to its vent and to its fixture outlet as structural conditions will permit.

(8) Length of tailpiece. The vertical distance from a trap to the fixture outlet shall not exceed 24 inches.

(9) Installation. (i) Grade of trap arm. The piping between a “P” trap and the fixture tee or the vented waste line shall be graded 1 ∕4 inch per foot towards the vent and in no event shall have a slope greater than its diameter. The vent opening at fixture tees shall not be below the weir of the “P” trap outlet.

(ii) Trap arm offset. The piping between the “P” trap and vent may change direction or be offset horizontally with the equivalent of no more than 180 degrees total change in direction with a maximum of 90 degrees by any one fitting.

(iii) Concealed traps. Traps with mechanical joints shall be accessible for repair and inspection.

(iv) Removability of traps, etc. Traps shall be designed and installed so the “U” bend is removable without removing the strainers from the fixture. Continuous waste and tail pieces which are permanently attached to the “U” bend shall also be removable without removing the strainer from the fixture.

(b) Cleanout openings—(1) Location of cleanout fittings. (i) Cleanouts shall be installed if the drainage system cannot be cleaned through fixtures, drains, or vents. Cleanouts shall also be provided when fittings of more than 45 degrees are used to affect an offset except where long turn ells are used which provide sufficient “sweep” for cleaning.

(ii) A full size cleanout shall be installed at the upper end of any section of drain piping which does not have the required minimum slope of 1 ∕4 inch per foot grade.

(iii) A cleaning tool shall not be required to pass through more than 360 degrees of fittings, excluding removable “P” traps, to reach any part of the drainage system. Water closets may be removed for drainage system access.

(2) Access to cleanouts. Cleanouts shall be accessible through an unobstructed minimum clearance of 12 inches directly in front of the opening. Each cleanout fitting shall open in a direction opposite to the flow or at right angles to the pipe. Concealed cleanouts that are not provided with access covers shall be extended to a point above the floor or outside of the manufactured home, with pipe and fittings installed, as required, for drainage piping without sags and pockets.

(3) Material. Plugs and caps shall be brass or approved or listed plastic, with screw pipe threads.

(4) Design. Cleanout plugs shall have raised heads except that plugs at floor level shall have counter­sunk s...

§3280.607 Plumbing fixtures.

(a) General requirements—(1) Quality of fixtures. Plumbing fixtures shall have smooth impervious surfaces, be free from defects and concealed fouling surfaces, be capable of resisting road shock and vibration, and shall conform in quality and design to listed standards. Fixtures shall be permanently marked with the manufacturer's name or trademark.

(2) Strainers. The waste outlet of all plumbing fixtures, other than toilets, shall be equipped with a drain fitting that will provide an adequate unobstructed waterway.

(3) Fixture Connections. Fixture tailpieces and continuous wastes in exposed or accessible locations must be of not less than No. 20 Brown and Sharpe gauge seamless drawn­brass tubing or other approved pipe or tubing materials. Inaccessible fixture connections must be constructed according to the requirements for drainage piping. The diameter of
each fixture tailpiece, continuous waste, or waste and overflow must be not less than:

(i) 1 1 ∕2 inches, for sinks of two or more compartments, dishwashers, clothes washing machines, laundry tubs, bathtubs, and showers; and

(ii) Not less than 1 1 ∕4 inches for lavatories or single compartment sinks having a 2­inch maximum drain opening.

(4) Concealed connections. Concealed slip joint connections shall be provided with adequately sized unobstructed access panels and shall be accessible for inspection and repair.

(5) Directional fitting. An approved or listed “Y” or other directional­type branch fitting shall be installed in every tailpiece or continuous waste that receives the discharge from food waste disposal units, dishwashing, or other forcedischarge fixture or appliance. (See also §3280.607(b)(4)(ii).)

(6) Water conservation. All lavatory faucets, showerheads, and sink faucets must not exceed a flow of 2.5 gallons per minute (gpm).

(b) Fixtures—

(1) Spacing. All plumbing fixtures shall be so installed with regard to spacing as to be reasonably accessible for their intended use.

(2) Water closets.

(i) Water closets shall be designed and manufactured according to approved or listed standards and shall be equipped with a water flushing device capable of adequately flushing and cleaning the bowl at each operation of the flushing mechanism.

(ii) Water closet flushing devices shall be designed to replace the water seal in the bowl after each operation. Flush valves, flushometer valves, flushometer tanks and ballcocks shall operate automatically to shut off at the end of each flush or when the tank is filled to operating capacity.

(iii) All water closets must be low consumption (1.6 gallons per flush (gpf)) closets.

(iv) Flush tanks shall be fitted with an overflow pipe large enough to prevent flooding at the maximum flow rate of the ball cock. Overflow pipes shall discharge into the toilet, through the tank.

(v) Floor Connection. Water closets must be securely bolted to an approved flange or other approved fitting that is secured to the floor by means of corrosion­resistant screws.

The bolts must be of solid brass or other corrosion­resistant material and must not be less than 1 ∕4 inch in diameter. A watertight seal must be made between the water closet and flange or other approved fitting by use of a gasket, sealing compound, or listed connector device.

(vi) Floor connection. Water closets shall be securely bolted to an approved flange or other approved fitting which is secured to the floor by means of corrosion­resistant screws. The bolts shall be of solid brass or other corrosion­re... material and shall be not less than one­fourth inch in diameter. A watertight seal shall be made between the water closet and flange or other approved fitting by use of a gasket or sealing compound.

(3) Shower compartment. (i) Each compartment stall shall be provided with an approved watertight receptor with sides and back extending at least 1 inch above the finished dam or threshold. In no case shall the depth of a shower receptor be less than 2 inches or more than 9 inches measured from the top of the finished dam or threshold to the top of the drain.

The wall area shall be constructed of smooth, noncorrosive, and nonabsorbent waterproof materials to a height not less than 6 feet above the bathroom floor level. Such walls shall form a watertight joint with each other and with the bathtub, receptor or shower floor. The floor of the compartment shall slope uniformly to the drain at not less than one­fourth nor more than one­half inch per foot.

(ii) The joint around the drain connection shall be made watertight by a flange, clamping ring, or other approved listed means.

(iii) Shower doors and tub and shower enclosures shall be constructed so as to be waterproof and, if glazed, glazing shall comply with the Standard for Safety Glazing Materials used in Buildings—Safety Performance Specifications and Methods of Test, ANSI Z97.1­2004 (incorporated by reference, see §3280.4).

(iv) Prefabricated plumbing fixtures shall be approved or listed.

(v) Shower and tub­shower combination valves must be balanced pressure, thermostatic, or combination mixing valves that conform to the requirements of ASSE 1016­2005, Performance Requirements for Automatic Compensating Valves for Individual Shower and Tub/Shower Combinations (incorporated by reference, see §3280.4).

Such valves must be equipped with handle position stops that are adjustable in accordance with the valve manufacturer's instructions and to a maximum setting of 120 °F. Hot water supplied to bathtubs and whirlpool bathtubs are to be limited to a temperature of not greater than 120 °F by a water temperature limiting device that conforms to the requirements of ASSE 1070­2004, Performance Requirements for Water Temperature Limiting Devices (incorporated by reference, see §3280.4).

(4) Dishwashing machines. (i) A dishwashing machine must discharge its waste through a fixed air gap installed above the machine, through a high loop as specified by the dishwashing machine manufacturer, or into an open standpipe receptor with a height greater than the washing compartment of the machine. When a standpipe is used, it must be at least 18 inches, but not more than 30 inches, above the trap weir. The drain connections from the air gap or high loop are permitted to connect to an individual trap to a directional fitting installed in the sink tailpiece or to an opening provided on the inlet side of a food waste disposal unit.

(ii) Drain from a dishwashing machine shall not be connected to a sink tailpiece, continuous waste line, or trap on the discharge side of a food waste disposal unit.

(5) Clothes washing machines. (i) Clothes washing machines shall drain either into a properly vented trap, into a laundry tub tailpiece with watertight connections, into an open standpipe receptor, or over the rim of a laundry tub.

(ii) Standpipes must be either 1 1 ∕2 inch diameter minimum nominal iron pipe size, 1 1 ∕2 inch diameter nominal brass tubing of not less than No. 20 Brown and Sharp gauge, or 1 1∕2 inch diameter approved plastic materials.

Receptors must discharge into a vented trap or must be connected to a laundry tub appliance by means of an approved or listed directional fitting. Each standpipe must extend not less than 18 inches or more than 42 inches above its trap and must terminate in an accessible location no lower than the top of the clothes washing machine. A removable, tight­fitting cap or plug must be installed on the standpipe when the clothes washer is not provided.

(iii) Clothes washing machine drain shall not be connected to the tailpiece, continuous waste, or trap of any sink or dishwashing machine.

(c) Installation—

(1) Access. Each plumbing fixture and standpipe receptor shall be located and installed in a manner to be accessible for usage, cleaning, repair and replacement. Access to diverter valves and other connections from the fixture hardware is not required.

(2) Alignment. Fixtures shall be set level and in true alignment with adjacent walls. Where practical, piping from fixtures shall extend to nearest wall.

(3) Brackets. Wall­hung fixtures shall be rigidly attached to walls by metal brackets or supports without any strain being transmitted to the piping connections. Flush tanks shall be securely fastened to toilets or to the wall with corrosiveresistant materials.

(4) Tub supports. Bathtub rims at wall shall be supported on metal hangers or on end­grain wood blocking attached to the wall unless otherwise recommended by the manufacturer of the tub.

(5) Fixture fittings. Faucets and diverters shall be installed so that the flow of hot water from the fittings corresponds to the left­hand side of the fitting.

(6) Hydromassage bathtub—(i) Access panel. A door or panel of sufficient size must be installed to provide access to the pump for repair or replacement.

(ii) Piping drainage. The circulation pump must be accessibly located above the crown weir of the trap. The pump drain line must be properly sloped to drain the volute after fixture use.

(iii) Piping. Hydromassage bathtub circulation piping must be installed to be self­draining.

(iv) Electrical. Wiring must comply with Articles 680.70, 680.71, and 680.72 of the National Electrical Code, NFPA No. 70­2005.

See the full text in PART 3280—MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS [PDF] newer copy retrieved 2017/07/13 - faster-loading

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