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Manufactured homes are built on a fundamentally different production model than site-built houses, and that difference runs through nearly every aspect of how they are constructed, transported, and eventually repaired after a loss. Rather than being framed on a foundation at the home’s final location, a manufactured home is built almost entirely inside a factory, on a permanent steel chassis with an integrated frame that remains part of the structure for its entire life, even after the home is set on a foundation or piers at its destination. That steel chassis is what allows the completed home, or in the case of a multi-section home, each completed section, to be transported over the highway on its own wheels and axles to the site.
Because the entire structure has to survive over-the-road transport, manufactured home framing uses connection methods and structural detailing suited to that stress, which differs in specific ways from typical stick-built residential framing even when the finished wall looks similar from the inside. Floor systems are built as a rigid unit over the steel chassis rather than over a site-built foundation, walls are often shorter in stud length with different connection hardware at the top and bottom plates, and roof systems on multi-section homes are engineered to be transported separately and then joined and sealed at the ridge once the sections are set together on site. That ridge seam, called the marriage line on multi-section homes, is a location that deserves particular attention during any inspection, since water intrusion at an improperly sealed marriage line can cause damage that is not always obvious from either the interior ceiling or a casual look at the roof from the ground.
Exterior siding on manufactured homes has historically differed from typical site-built siding as well, with vinyl and metal lap siding common on older units and a wider range of siding types, including products closely resembling site-built materials, appearing on homes built in more recent decades. Roofing similarly evolved over time, with many older manufactured homes originally built with a low-slope roof design that has often been retrofitted with a pitched roof structure added over the original roofline by homeowners or previous owners seeking better snow shedding and reduced ice damming in cold climates like Minnesota’s. When evaluating storm damage on an older manufactured home, determining whether the roof structure being inspected is the original factory roof or a later site-added retrofit roof is an important early step, since the two can have very different construction quality and repair considerations.
Skirting, the material enclosing the space beneath the home between the chassis and the ground, and the tie-down or anchoring system securing the home to its foundation or piers, are components unique to manufactured housing that have no real equivalent in site-built construction. Wind damage evaluation on a manufactured home needs to consider these components specifically, since a home that has come loose from its anchoring system, even partially, represents a different category of damage than surface damage to siding or roofing, and anchoring failures are not always visually obvious without a direct inspection underneath the home.
Because so much of a manufactured home’s structural integrity depends on how well it was originally installed and anchored at its specific site, rather than purely on how it was built at the factory, site-specific installation records, when available, are a useful reference point during any damage evaluation involving structural or foundation-related questions.
This article is general education about how the appraisal process commonly works. It is not legal advice, and specific procedures can vary by state and policy.
Russ Lis is a working property insurance appraiser and umpire based in Minnesota, serving clients nationwide. Contact Appraisal Resolution.