Primary Distinctions Between Site-Built Homes and Manufactured Homes

(The following narrative contains excerpts from a comprehensive report titled “Mobilizing Energy Efficiency in the Manufactured Housing Sector” by the American Council for an Energy-Efficient Economy).

For many, the term “mobile home” conjures images of either rural trailer parks or the unpopular emergency (FEMA) houses delivered to the Gulf Coast following Hurricane Katrina and Rita. These stereotypes reinforce the commonly held belief that manufactured homes are substantially different and inferior to site-built homes. While there are differences in design and the construction process, manufactured and site-built homes actually share primary techniques and materials.

There are two primary distinctions between site-built and manufactured homes: first, manufactured homes feature a permanent chassis underneath the house: and second, manufactured homes are constructed in a factory facility and transported to an installation site as a complete structure (multi-section homes are transported as separate sections and assembled on site). Wheels are attached to the chassis for transportation from the factory and then removed during installation, but the chassis stays in place. The chassis allows the owner to relocate the home if desired, although, in practice, this happens infrequently. In fact, 67 percent of occupied homes are located on their original foundation (Census 2011). Modular homes, also built in a factory, do not include the chassis.

During its approximately fifty-year history, the manufactured housing industry has changed dramatically. The house-on-wheels designs of the 1950s have disappeared from showrooms, replaced by homes that fit in many ways more closely resemble their site-built counterparts than the freewheeling structures of the past. Even the term mobile home has largely become a passe in the industry, which has adopted manufactured housing as the preferred nomenclature.* This deliberate shift in semantics alludes to the changes in building design, construction, and installation that have occurred in the past half-century. That is, modern manufactured homes are built to last many decades and rarely move from their initial installation sites. In fact, today, the manufactured housing industry competes directly with the site-built industry, particularly among first-time, retired, and low-income home buyers seeking an affordable route to homeownership.

*Despite manufacturers’ usage of the term “manufactured housing,” surveys conducted by the Manufactured Housing Institute, the trade group for the manufactured housing industry, suggested that most manufactured homeowners still refer to their homes as “mobile homes” (MHI 2011).

Siting differs between site-built and manufactured homes. The majority (60 percent) of manufactured homes are installed on concrete blocks or metal piers. Another 18 percent of homes are installed on a permanent foundation, and 17 percent are on a concrete pad (Census 2011). Even for homeowners who plan never to move their home, the preference for concrete blocks makes some financial sense, as site preparation and home installation may comprise 14 percent or more of total home costs, and siting a home on concrete blocks costs less than concrete pads and permanent foundations. On the other hand, sitting a manufactured home on a permanent foundation makes it easier for a homeowner to qualify for a conventional mortgage, which can reduce interest rates and monthly payments on loans.


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