San Diego Home Inspector Inspecting Mobile Homes

INTRODUCTION- to the Inspection of Mobile Homes for Defects

Consumer Reports (2/98) points out common weak spots surveyed and recommends that buyers hire a home inspector. But many inspectors are not familiar with the special problems found in mobile homes.

PRIORITIES OF INSPECTION & Reporting of Mobile Home Defects

MOBILE HOME FIRE SAFETY - Fire Safety Defects in Mobile Homes

Electrical
Heating, flues, chimneys
Safety Exits - doors and push-out windows
Smoke detectors critical - short exit time for this construction

STRUCTURAL & SAFETY DEFECTS in Mobile Homes

Movement (impacts electrical & flues)
Storm Damage
Floor Collapse (particle board, exterior & plumbing leaks)

MOBILE HOME LABELS - Mobile Homes and Manufactured Housing Labels & Certifications

INSTALLATION MANUAL - For new/recent mobile home, every manufacturer is required to provide instructions on site preparation, installation and anchoring.
Manufacturer's CERTIFYING LABEL - on rear section outside or near the main entry door, HUD Insignia

DATA PLATE - near the main electrical panel or other visible & accessible location (under sink for many manufactured homes): name of mfg., serial and HUD ID, zone information (see Structure discussion)

DAMAGE DURING TRANSPORT: if the unit was damaged during transport it no longer conforms to the standards and should not be accepted by the code official;

ROOFING DEFECTS - Inspecting for Mobile Home Roofing Defects

31% of mobile homes had roof problems; (C.R. survey)
flat or near-flat, may be covered with conventional shingles (slope too low)

chimneys or plumbing vents "patched-over" so as to be blocked

dents and ponding and leaks at seams (patching with roof cement fixes leaks but corrodes metal)

roofs with no overhang: frequent leaks in walls at windows or wall tops;

Shingled roofs usually have overhang (added?); flat roofs don't. Metal roof seams leak;

EXTERIOR DEFECTS - Inspecting for Mobile Home Exterior Defects

usual site drainage requirements

Building officials should have checked the home location for proper setbacks from property boundaries etc. - a buyer should be sure that this information has been reviewed and that a CO is on file.

The Building address needs to be visible from the road, letters 4" high and reflective on contrasting background for recognition of the property by emergency vehicles.

steps and rails: need 2 exit doors/steps/rails, usual step and platform issues; doors usually at either end of one side or at opposite ends and opposite sides; 30 ft apart.

Fire escape: assure functional second egress door, steps, rails, etc. Have found doors that didn't open or that opened to tall drops where deck was rotted and then removed.

Missing stairs: there must be an exit platform and stairway at every exterior door. We have found doors opening to a 6' drop where a stair had never been installed or had been removed because it was rotted.

older units, bad leaky windows - beware: leaks into walls invite rot and insect damage. Check the floor below windows and doors, and inspect this area carefully from the crawl space.

skirt condition, missing, avenue for insect attack and rodent entry. In cold climates a missing skirt can lead to frozen burst pipes and related damage. find opening (s)

site concerns: open septics; inadequate. frost protection for supply or DWV; shared wells, shared septics, possibly not tested nor maintained;

Siding: vinyl preferred over metal or hardboard (C.R.)

Site debris: may be unsafe, a sanitary or other Building code violation, source of rodents, or otherwise a cost to a buyer to have removed.

FOUNDATIONS Common Mobile Home Foundation Defects

Systems used: Perimeter concrete, concrete block; piers and/or posts; concrete slab; piers and ground anchors; permanent wood;
Preventing frost damage: footings below frost; floating slab; other engineered design;
Preventing wind damage: ground anchors & ties; ties to concrete dead men, footings, or foundation; other engineered design;

MOBILE HOME PIERS - Mobile Home Pier Foundations

slab preferred; assure good drainage away (risk undermined piers); (Floating or on frost footings ok)

missing or improper tie-downs against storm damage (Northridge disaster & in FL); tie-downs may be driven or screwed into ground; cables must be taut.

improper masonry piers-blocks on sides, stacked debris, removed chassis, water-undermined piers; footings/piers often not below frost line; reinforced floating slab may work ok;

piers at excessive intervals (more than 6-8 feet and/or closer than 3 ft. to the ends of the home)

piers missing at large sidewall openings (sliders) or at tip-outs or expanded units or under fireplaces.

masonry piers: properly-stacked blocks, hardwood or treated wood or concrete cap, shims; piers sit on 16"x16"x4" concrete pad, precast or poured in place, or 12" x 20" treated wood;

Piers less than 36" high can be single-stacked 8x8x16" block with the long 16" dimension perpendicular to the frame;

Piers 36" to 80" high and all corner piers of more than 3 blocks high shall be double-blocked with interlocking alternating courses and capped with 5x16x16 solid concrete block or equivalent;

Piers more than 80" high must be double blocked, alternating courses, laid in mortar and steel reinforcing rods set in block cells and cells filled with concrete.

NO more than 4" of wood in space between pier and frame; No more than 1" thick shims and must be tight;

metal stands (jacks) on soil surface likely to shift/tip/settle; Steel piers should be on concrete soil pads/footings;

settlement: may show up in hard-to-operate windows/doors;

STABILIZING SYSTEMS - Tie Downs for Mobile Homes

DEFINITIONS:

Stabilizing Devices: all components of the anchoring & support systems
Support System: combination of footings, piers, caps, shims that support the home
Anchoring System: system to resist overturning and lateral movement
Anchoring Equipment: combination of straps, cables, turnbuckles, chains and tensioning devices.
Anchor: device secured in the ground (Screw or other)
Tie: cable, chain, strap and tensioning device; Diagonal ties, or frame straps, at 45 deg. angle attach to main frame at one end and to ground at other to resist lateral movement; Ground anchor should be about at same angle as the strap; May be vertical; Diagonal ties for double-wide units are required only at outside rails of each unit; Vertical straps or ground straps resist uplift and overturn, required only for hurricane or wind zones;
The number and placement of tie downs for mobile homes and trailers depends on the wind zone in which the home is located and the length of the structure. For example, a 65' trailer would need 2 to 3 vertical tie downs per side, or 4 to 6 tie downs per side if diagonal tie downs are used, depending on which wind zone it's in.
Connection: the mobile home tie down is connected to the steel I-beam at specific locations provided by the manufacturer; typically strap wraps around the I-beam.

Tie downs are usually expected to be placed and connected according to details provided in the mobile home installation manual (have you ever seen one?). If you know your mobile home or trailer model name and perhaps serial number, you may be able to contact the mobile home manufacturer to ask for an installation manual.

MULTI-WIDE CONNECTIONS - Multi-Wide Mobile Home unit connections:

lag screws or through bolts at adjacent mate beams, especially important if the manufacturer has support columns under only half of the home;

hinged roof connections require that king posts be site-installed and metal uplift straps secured to the mate lien wall and roof assembly once the hinged roof is up;

WALL DEFECTS - Defects in Mobile Homes

watch for furring strips and aluminum siding vs. real 2x4 or 2x6 studs 16"o.c.
watch for short walls less than 7'6" (C.R.) - short walls mean special short doors, furring strips means no real insulation;
Sheathing: OSB or plywood under vinyl; metal siding may have no sheathing = weaker structure;
metal siding: leaks at decorative railing/trim (horizontal); leaks at doors and windows;
hardboard siding: leaks at seams and joints; poor material, short life;

CRAWL SPACES - Mobile Home Crawl Space Concerns

openings, damaged insulation, leaking pipes, improper plumbing and wiring
violations of proper clearance to ground:
12" minimum beneath lowest frame member and ground in area of utility connections;
no more than 25% of the main frame can be less than 12" above grade;
If over basement or habitable lower level or more than 1/4 of home is more than 3' above grade a professional must design the foundation;
belly wrap (plastic or other) to seal out moisture and hold in insulation:
often damaged or pulled out for repair; rodents, water, leaks; air leaks;
look for termites & carpenter ants - up skirt into floors/walls esp. @ leaks (plumbing, windows, doors)

GENERAL STRUCTURAL - General Mobile Home Structural Concerns

support added for sagging roofs/ceilings, makeshift, improper

ELECTRICAL DEFECTS - in Mobile Homes

Common electrical defects in mobile homes are discussed below.

ELECTRICAL SUPPLY - Defects in Mobile Homes

meter & disconnect separate from the home, with own grounding electrode; therefore the panel in the home must be wired like a sub panel (isolate ground and neutral in the panel) with a 4-wire conductor that separates ground and neutral.
Factory-installed electrical equipment will have the bonding screws removed (dryer, range). Same must be done with owner-installed equipment..

ELECTRICAL SERVICE - Drop Feeders for Mobile Homes

Traditional: cord and plug method to main switch;

Service equipment must be in sight of and no more than 30 ft from the exterior wall of the home it serves;

Cord and plug limited to 50A, sometimes 40A

Permanent feeders: SEC adjacent to home or mounted in the home provided manufacturer installed; may enter underground via conduit; If overhead, look for 4 color coded conductors ; (Hot, Hot, Neutral, Ground);

Masthead must give 8ft vertical clearance from all points of all roofs over which conductors pass, 2 exceptions:

3ft ok if roof is 4 in 12 or more

18" ok if no more than 4' of service drop conductors pass over the roof overhang and if terminate in a through-roof raceway

ELECTRICAL GROUNDING - for Mobile Homes

Neutral bond separated from Ground in panels wired as subs
Often no metal water pipe entering the unit to serve as ground
Metal shell & Frame & Panel MUST be grounded (electrocutions & fires common from this defect)

COMMON DEFECTS in Mobile Home Electrical Wiring

improper connection to site, service entry, support, clearance over roofs

aluminum wiring

lots of do-it-yourself wiring, exposed splices, bad or no GFCI, lamp cord wiring

due to limited storage space access to panel often blocked

abandoned fixtures or boxes left open to weather

GFCI missing at baths, kitchens, outside, or mis-wired;

Loose, falling fittings and lights and fixtures inside and out;

MOBILE HOME HEATING System Defects

General Characteristics:

Hot air, gas-fired, central return heating units are most common ; oil & electric mobile home heaters are also used;
20% of mobile homes have problems with HVAC (C.R. survey);

Common Defects in Mobile Home Heating Systems

fuel connection should have label indicating equipment and piping are ok for natural or LP gas or both; inadequate combustion air

inadequate clearance to combustibles modified equipment, controls, flue-vent connectors, burners, duct work, venting

air heat: all return air taken from crawl area beneath living unit - one-way heat; blocked return; blocked supply; ducts through un-heated area; NO return air, or none when utility closet door is shut!

LP Tanks, copper gas lines are often left unsupported and exposed to mechanical damage; also check for LP gas leaks at tanks or fittings;

Oil tanks - indoor-rated heating oil tanks are quite often placed outside, above ground, in ground contact, with heat tapes (a fire hazard), often leaking, and in cold climates, exposed to frost-risk which in turn risks loss of heat and related damage to the home

missing or still-covered-over spark arrestor on the heating flue

MOBILE HOME COOLING System Defects - Air Conditioning

General Characteristics of Mobile Home Cooling Ducts

Ducts placed at one of these typical locations:
- cooling ducts placed in the floor along center line of the mobile home;
- cooling ducts placed in the floor along exterior walls (better heating in cold climates);
- cooling ducts placed in the in trailer or mobile home ceiling (better cooling in South); [The duct location may tip off the wind zone rating intended for the mobile home unit being inspected.]

Common Defects

floor ducts often damaged; registers blocked or covered

MOBILE HOME INSULATION and Ventilation Defects

crawl: sq ft/150 = min area and must cross vent on at least 2 sides;

PVC on soil recommended to hold down moisture;

attic venting (sloped shingled roofs) - often omitted, shorter shingle life, voids warranty, &c;

attic venting (often none or just a few spot vents in flat roofs) - condensation, leaks, related damage.

check dryer vent routing and materials for fire hazards (blocked overheats dryer; or may collect water)

MOBILE HOME PLUMBING Defects

GENERAL PLUMBING - Comments for Mobile Home Inspectors

36% of mobile homes report problems with plumbing (C.R. survey)
most common complaint according to C.R. - 1/3 homes have problems;
Low quality sinks, tubs, showers, faucets (molded plastic faucets, fixtures; porcelain or acrylic preferred)
no shutoff valves especially at toilets
leaks damage structure, especially with use of particle board sub flooring.

SUPPLY PIPING - Mobile Home Supply Piping Defects

PB (polybutylene with mechanical fittings) Piping leaks: especially in South e.g. FL per M Cramer
New units: 3/4" supply piping, min 6" off ground; shutoff valve required;
Freeze Protection for Mobile Homes and Trailers:
- 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.
- 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 Drain Waste Vent Piping Defects

leaky traps rot walls and floors faster than conventional construction.

drains added (added laundry or bath) not under unit or ?

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);

MOBILE HOME FUEL SUPPLY Defects & Concerns, gas and oil piping

gas piping: crossover flex connector at mate line of adjacent units;
tank location - per manufacturer and code;
gas and oil shutoffs required per usual locations
meter base: manufacturer may spec min distance from the gas inlet;
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.

Note that CPSC recommends this procedure 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.

WATER HEATER Defects in Mobile Homes

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

MOBILE HOME PLUMBING Fixture Defects

Tubs: usual leaks at fittings; missing components, history of leaks and no maintenance;

INTERIOR DEFECTS Defects in Mobile Homes

32% of mobile homes report problems with windows or doors (C.R. survey)

Hardboard floors - get wet, toilet falls through; plywood preferred; check especially floors at baths, kitchens, and below windows and doors

Walls: paneling or drywall

Windows: often single-glazed, glued or screwed frames (leaky); welded vinyl perform better; caulking often missing between window frames and sheathing (water damage) - same at doors; Caulk at door and window gaps (from factory) may break during transport;