PATH - A Public Private Partnership for Advancing Housing Technology

Guide to Foundation and Support Systems for Manufactured Homes

March 2002, 112 pages

In an evolving marketplace, newer foundation choices abound. Do you know how to pick the right one?

FULL TEXT: Adobe Acrobat (*.pdf, 7.7 MB)

NOTE: Adobe Reader is required to download, view, and/or print PDF files. If your computer does not have this software, you must first download Adobe Reader, and follow the installation instructions before accessing PDF files from PATH's Web site. [IMAGE: A graphic of All Steel Foundation Model #1100. Photo courtesy of Oliver Technologies.]

The changes in the manufactured housing market, the evolution of the industry itself and the diversification of the potential customers for manufactured homes are ushering in a host of innovations and changes to the industry's core product. No area is more affected by these changes than the methods for supporting and fastening the home to the ground.

This guide helps decision makers in formulating a strategy for sorting among foundation and support system alternatives and describes factors that impact the design and construction process. The guide also exposes the manufactured housing industry and buyers to some of the more popular and practical ways of designing and installing manufactured home foundation or support systems. These designs are springboards for exploring alternative design approaches and solutions. Through the use of case studies, the guide examines how some practitioners are already pursing new foundation and support system methods, hinting at the wealth and diversity of foundation solutions yet to come.


Recommendations:

  • Be sure that the foundation system you select is one that is familiar and acceptable to construction and mortgage lenders. Before settling on a system that is intended to have a real property classification, it is always prudent to confer with area lenders about locally acceptable foundation systems. (For more discussion of this topic, see page 1.3.)
  • If possible, have all pre-delivery work done a day or so before the home arrives. Doing pre-delivery work any earlier could affect the cost of borrowed construction funds; any later could mean the house is in the way while the work is being finished. It is prudent to budget extra time for site work the first few times a new system is specified.
  • Coordinate the design of the connection with the manufacturer. For all of the foundation systems presented in this guide, there are numerous ways homes are attached to their foundations, and ultimately to the ground. Direct bolting and nailing are very common. If a steel-to-steel connection is involved, welding is optimal.

See Table 2.1 for basic soil characteristics and their implications on foundation choice.

See page x, Table I.1, for a quick review of the foundation systems included in the guide and decision factors for each.

See page 3.2 for information on pier and ground anchor support systems, the most popular method of securing manufactured homes to the ground.






Key Results:

  • There is no single "best" foundation system. When comparing foundation systems, consideration of each should include ventilation factors; methods of attachment; construction challenges; initial cost; real propery classification; installation time; and resistance to wind, floods, gravity, frost and seismic loads. For example, basement foundation systems are far more expensive than other systems, are not recommended in flood-prone areas, and require more installation time. However, they can add significant amounts of usable space to a home; qualify as a real property foundation; and will resist wind, gravity and seismic loads when properly engineered.
  • As opposed to the HUD code, which is preemptive of local codes and creates uniformity of manufactured home construction across state lines, foundation systems are typically subject to state or local building codes. So, while the homes themselves may enjoy consistency of design and construction, foundation plans are subject to review by the local code enforcement authorities.

Content updated on 11/22/2006

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