How to Inspect the Plumbing Systems of Mobile Homes, Double wides, Trailers InspectAPedia® -
Mobile home plumbing 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
Our site offers impartial, unbiased advice without conflicts of interest.
We will block advertisements which we discover or readers inform us are associated with bad business practices,
false-advertising, or junk science. Our contact info is at
InspectAPedia.com/appointment.htm.
How to Inspect Mobile Homes or Manufactured Housing for Defects: detailed procedures, defect lists, references to standards.
Ver.3.4 - 04/25/07 - 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.
no shutoff valves especially at toilets in mobile homes and trailers
leaks damage structure, especially with use of particle board sub flooring.
SUPPLY PIPING - Mobile Home Supply Piping Defects and Plastic or polybutylene water supply piping failures, leaks, and litigation
PB (polybutylene with mechanical fittings) Piping leaks: especially in South, for example trailers and double-wides throughout Florida that were piped with this material - per M Cramer. See "Polybutylene Piping: Time Bomb?" Daniel Friedman, Journal of Light Construction, August 1996 [Technical Q&A].
If plastic water piping is installed, such as polybutylene water supply piping, it should be at least 18" from the water heater.
New mobile home and trailer units: 3/4" supply piping, min 6" off ground; shutoff valve required;
Freeze Protection Suggestions for Mobile Homes, Double-Wides and Trailers:
Note on use of heat tapes on plumbing or oil piping: The US CPSC recommends that heat tapes be connected to a GFCI-protected electrical receptacle (or on newer wired-installations AFCI circuits) for fire safety but HUD rules do not allow connection of the
heat tape to GFCI because they don't want to risk frost damage: so note
conflict between frost damage and life-safety concerns. Heat tapes used on
exposed plumbing at extra risk of freezing, e.g. below the units.
If mobile home supply piping has frozen, burst, and leaked into the structure,
you'll need to remove and discard any wet insulation - or else face a mold problem.
Simply adding insulation, in any amount is by itself unlikely to be sufficient to protect
a mobile home from freezing if it's left unattended with heat off.
Rather people design the plumbing to be drained when the home is left.
If the trailer or mobile the home is occupied then you'll need to look carefully at
supply pipe routing and maybe even add heat in some areas.
We dislike heat tapes - as they can be unreliable and possible fire hazards, but they can work in some cases.
High-quality plumbing pipe heating tapes that can be crossed over one another without melting and shorting
out (fire hazard) are available. Of course if the home loses electrical power this solution won't help much.
To reduce the mobile home fire risk when using heat tapes, use metal-braid shielded heating cables connected to
a GFCI protected electrical outlet so that if the
heating tapes short out the circuit will trip.
Trailer & mobile home water entry lines are often exposed to freezing below the unit - (photos above left and right).
If the mobile home water supply is provided by a pump and the pump is found to have
cracked (and the home is located in a climate where freezing weather occurs, pump cracking probably means it froze
and was not drained or protected from freezing.
If mobile home drains are freezing the same frost protection or heating concerns need to be addressed
as we've just listed.
Open drains or leaky connections (crawl)
Leaky supply main (crawl)
DRAIN WASTE VENT - Mobile Home & Trailer Drain Waste Vent Piping Defects
leaky traps rot walls and floors faster than
conventional construction especially where OSB or chipboard was used for subfloor material in the mobile home or trailer
Drains added (added laundry or bath) not under unit or ? (photo at above left shows a laundry drain spilling onto the yard surface by the mobile home)
look for leaks into the crawl area;
look for proper slope 1/8" /ft, and support
(no less than 4ft o.c.), and
direction of fittings, and proper adhesive (DWV
for PVC, ABS or both);
Damaged plumbing fixtures, leaky sink traps, unsafe electrical receptacles or no GFCI's in bathrooms and kitchens - our photo at left shows a leaky sink, improper (down-sloping) drain connection to a laundry at left of the sink tailpiece, and leaks that have created a mold problem in this mobile home.
MOBILE HOME & TRAILER or DOUBLE-Wide Heating FUEL SUPPLY Defects & Concerns, gas and oil piping
Mobile home and trailer gas piping: crossover flex connector at mate
line of adjacent units
LP tank or oil tank location - per manufacturer and code;
Gas and oil shutoffs required per usual locations - at but not inside the appliance cover
Gas meter base: if a gas meter is installed, the manufacturer may specify the minimum distance from the gas inlet; because installation is done on limited budget it's often by people who are not trained and don't know these or other safety requirements
Gas piping supplying LP gas to the mobile home, trailer, or double-wide home is often not protected from damage (photo at left - Steve Vermilye)
Heat Tapes - use metal-braid shielded type connected to GFCI so if short will trip. Heat tapes, especially the non-shielded types,
short and start fires, especially if crossed over themselves or otherwise improperly installed.
Oil tank support (often falling or in ground-contact) see our photo at page top
Oil tank gauges and fill and vent piping - exposed to water entry from roof spillage or, as in our photo, from a makeshift repair to a fuel gage or other tank connection
WATER HEATER Defects in Mobile Homes, Trailers, Double-Wides
Heat Tapes - use metal-braid shielded type connected to GFCI so if short will trip;
gas-fired in sleeping areas
electric (usually); bad wiring connections,
tipped on rotting floors,
relief valves: to hidden location (below
trailer, can't see leaks), and usual issues of down-sized pipes
Improper exhaust venting, risk dangerous carbon monoxide leaks into the interior - see Carbon Monoxide - CO
MOBILE HOME PLUMBING Fixture Defects
Tubs: usual leaks at fittings; missing components,
history of leaks and no maintenance;
Fixtures or fixture drains damaged from freezing underneath the home in cold climates
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Additional technical contributors & reference sources for this article are listed below.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
"Modular Home Construction, special defects and inspection methods" Dan Friedman, NY Metro ASHI Seminar, Holiday Inn, Crowne Plaza, White Plains NY, October 4, 1996
"Modular Home Construction, special defects and inspection methods" Dan Friedman, NY Metro ASHI Seminar, Holiday Inn, Crowne Plaza, White Plains NY, October 4, 1996
"Modular Home Construction, special defects and inspection methods" Dan Friedman, NY Metro ASHI Seminar, Holiday Inn, Crowne Plaza, White Plains NY, October 4, 1996
New York State: "Manufactured Homes: an installation guide for the code enforcement official," undated. [Div. of Code Enforcement & Admin. - 518-474-4073, George E. Clark, Jr., Director] - this is a guide tool, not an enforcement code or standard.
HUD State Administrative Agency (for 36 states) (NY: 518-474-4073) - for complaints
Manufactured Housing Institute, 2101 Wilson Blvd. Ste. 610, Arlington VA 22201 703-558-0400 www.mfghome.org
NYMHA, 35 Commerce Ave., Albany NY 12206-2015 518-435-9859 800-721-HOME (they want the Star Program to provide for separate assessment of manufactured homes)
Consumer Reports: www.consumerreports.org - special report 2/98
More Information on Building Diagnostic Inspections and Repairs
...
InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.
The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems
Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.