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Mobile home crawl spaces.
This article describes the common defects that can be observed in the crawl space below a trailer, mobile home or doublewide home.
We include descriptions of the manufactured home or mobile home crawl space inspection components, both things that should be present (e.g. belly wrap, proper clearances) and also things that should not be present (rodents, leaks, wheels).
Manufactured & Mobile Home Crawl Space Code Specifications
When inspecting a mobile home or doublewide crawl area, be sure to look for evidence of these common defects:
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Axle, Tongue & Wheels should have been removed from a mobile home or manufactured home if it is to meet current U.S. HUD/FHA Manufactured Home standards.
Belly wrap (plastic or other) to seal out moisture and hold in insulation:
Clearances: the mobile home must have a minimum of 18" of clearance space between the ground surface and the bottom of the beam or girder supporting the home and that rests on the pier tops or foundation.
Other standards include:
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;
Ductwork for HVAC system damaged, contaminated, not functional
Flooding, mold contaminated insulation. Check the crawl space for signs of water entry right in the crawl itself; the skirt around the mobile home can keep the area from drying out.
Remember to look with care at the floor structure overhead, as you may find evidence there of leaks from above originating at the roof, walls, windows, doors, or plumbing system.
Foundation requirements: properly-constructed piers and proper footings below piers. A stack of hollow core blocks on their side sitting on wood scraps is not a safe nor adequate manufactured home foundation. See MOBILE HOME FOUNDATIONS and see MOBILE HOME PIERS
Freeze damaged plumbing
Insulation has often damaged or pulled out for repair; rodents, water, leaks; air leaks;
Insect damage & rot: look for termites & carpenter ants - up skirt into floors/walls esp. @ leaks (plumbing, windows, doors)
Moisture barrier: dirt floor crawl space surfaces under a manufactured home or mobile home must be covered with a 6-mil polyehtylene (or equivalent) moisture barrier
Openings, damaged insulation, leaking pipes, improper plumbing and wiring
Site grading should not direct surface runoff nor roof spillage under the home but rather must direct it away). The skirting must be "self supporting" and rest on a concrete footing (to meet HUD/FHA Manufactured home specifications.
Skirting around the manufactured/mobile home base: must be complete, intact, and include an access opening. The mobile home foundation perimeter wall ("skirt") has to enclose the foundation to resist vermin or other animal pests and to resist wind-driven rain.
Skirting around the crawl space of a manufactured home or mobile home can be made of various materials, masonry block, brick, treated wood, resting on a concrete footing. (Older aluminum or vinyl siding skirting won't quality co reinforced floating slab may work ok;
Permieter walls have to be at least 8" above surrounding grade.
Structural damage: for doublewides inspect the center mating girder for signs of separation that may indicate framing damage, rot, poor original construction, or settlement of the supporting piers of the home's perimeter.
Utility Connections: often visible below the manufactured or mobile home: must be permanently-installed. An "extension cord" hookup for electrical power, a garden hose for water supply, etc. are not acceptable.
Ventilation of the crawl area: current U.S. HUD/FHA standards require one square foot of ventilation opening (screened foundation vents or skirting vents) per 150 square feet of the home's crawl space floor.
A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
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Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting: A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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