HUD/FHA Manufactured Home Permanent Foundation Certification
A Manufactured Home is defined as a structure built on a permanent chassis, transportable in one or more sections that are no more than 8 feet wide and 40 feet long, or 320 square feet when erected on the site. It is designed to be used as a dwelling and contain plumbing, heating, air-conditioning and electrical systems. The category does not include recreational vehicles (RVs), structures designed for temporary living, or modular homes.
Mortgages are available for the purchase of new or existing manufactured homes. Most mortgages written by a lender are almost certain to be insured by the Federal Housing Administration (FHA), a division of the U.S. Department of Housing and Urban Development (HUD).
As a condition of providing insurance, the FHA requires that the foundation for new homes be designed by, and the design sealed by a licensed Professional Engineer. The design must comply with FHA guidelines. For existing homes, a Professional Engineer is required to certify that the foundation meets the FHA requirements.
A permanent foundation is one that is “constructed of durable materials (concrete, mortared masonry, treated wood) and be site built. It shall have attachment points to anchor and stabilize the manufactured home to transfer all loads to underlying soil or rock. The permanent foundations shall be structurally developed in accordance with this document or be structurally designed by a licensed professional engineer.” Although the design must comply with the manufacturer’s instructions, doing so does not guaranty that it complies with the HUD Guide.
The design must provide vertical stability.
- Anchorage capacity to prevent uplift and overturning due to winds or seismic forces, whichever controls. Screw-in soil anchors are not considered permanent anchorage.
- Footing size to prevent overloading the soil-bearing capacity and avoids soil settlement. Footings shall be reinforced concrete to be considered permanent.
- Base of footing below maximum frost-penetration depth.
- Enclose a basement or crawl space with a continuous wall (whether bearing or non-bearing) that separates the basement of the crawlspace from the backfill, and keeps out vermin and water.
The design must provide lateral stability with anchorage capacity to prevent sliding due to wind or seismic forces, whichever controls, in the transverse or longitudinal direction.
There are two methods to prepare acceptable design solutions. The first is to offer an engineered solution using the Guide criteria. The second is to use the appendices in the guide and the worksheets offered to select and document a design of an approved type.