Refine Search

Factory-built Houses​—Which One Would You Buy?

JOHN liked Michael’s house plans. “I want to give my builder the same plans and have him build my house exactly like yours.” John did. When finished, the two houses looked alike. But they were not built alike. Michael had ordered his house ready-built from the factory. It was delivered in two long halves. A crane lifted each of the halves or sections off the flatbed conveyers and set them side by side on the foundation. A carpenter joined the sections by closing in the gables and covering the interior seams with molding strips. Within two weeks after Michael’s foundation was prepared, his house was finished and landscaped and ready to be occupied.

John’s house took months to complete. His contractor used the conventional “stick-built” method of building the house right there on the site.

John mused: “Maybe Michael was smart to order his entire house ready-built. . . . But I was suspicious that all he was getting was a fancy mobile home.” Most people think like John, that the only sort of dwellings to come out of factories are cheap, flimsy “house trailers.”

But during the past 10 years especially, a growing number of “house shops” have appeared. Usually they are small, independent single-plant manufacturers compared to giant mobile-home corporations with chains of plants. The houses they build, so long as the style and shape are kept fairly clean and simple, are hard to tell apart from conventional houses whether finished in wood, metal or masonry veneer. How, then, can the houses they build be distinguished from their forerunners, the mobile homes?

Michael’s “Shop-Built” House

It is a matter of building codes and standards. Some American states have administrative boards to supervise factory-built housing. The state or its agency takes responsibility to inspect the houses as they are built on the factory assembly line. It requires them to meet the same general construction standards as “site-built” houses of the same type. Structures meeting its standards are then “deemed to comply with the requirements of all ordinances or regulations enacted by local government,” quoting from “Rules of Georgia State Building Administrative Board” regulating Factory Built Housing, Chapter 90-2-7(4).

This means that a house bearing that state’s emblem or decal of approval can be sited just about anywhere the owner pleases within the State of Georgia, because state ordinances overrule local ordinances that might prohibit, for instance, a mobile home. It is very important to make sure before contracting for a manufactured house that it can be sited where you want it. An unbelievable number of people buy a manufactured house only to discover to their dismay that it cannot pass some local ordinance restricting it to a mobile-home rental park or mobile-home subdivision.

The house Michael ordered meets conventional building codes for houses. Mobile homes are built to a different code. For example, part of a mobile home is the steel underbridging with axles, wheels and pulling hitch. While the “running gear” can be removed, the underbridging or chassis cannot. It is part of the floor construction. Now, Michael’s house had no underbridging attached. His two house sections were delivered on conveyance platforms called “lowboys.” When the crane lifted the sections off the “lowboys” there was nothing underneath but conventional wood-floor joists to rest on the foundation. The “lowboys,” or delivery flatbeds, are returned to the factory.

Fred’s “Modular” House

John and Michael have another friend, Fred. Fred bought a “modular” house. Fred’s house was the same size as theirs, 24 feet (7 meters) wide and 70 feet (21 meters) long. (There is a wide range in sizes.) Fred’s house has a gable roof like theirs, and rough wood siding. By the way, Fred got his house fully furnished, with everything color coordinated by a professional decorator. When the area was landscaped a casual observer could not distinguish Fred’s house from theirs.

What is the difference? There might be a host of minor differences that appear on closer scrutiny. For example, Fred’s partition walls might be thinner than Michael’s. But when Fred looks under his “crawl space” he sees one obvious difference. The bottom of his house includes the big steel underbridging. The steel chassis rests on the foundation piers and the perimeter walls, and the wood subfloor rests on the chassis. Fred boasts that his house has two foundations, one wood, one steel.

Think of Michael’s “shop-built” house and Fred’s “modular” house as representing two layers on a cake. Michael’s is the top layer because it is built to a code similar to that of conventional housing. Fred’s is the next layer. His house meets a different building code. It is one of three national building codes, either UBC, BOCA, or SBCC. One or the other of these codes is represented by an insignia or decal somewhere on Fred’s house. It testifies that the codes people or their “third party” agency are responsible for inspecting the house on the assembly line. If city and county governments want to, they can prohibit a “modular” house like Fred’s from being sited in just any area he might choose. On the other hand, they might not consign it to mobile-home locations. It usually ends up in areas zoned for lower-cost housing or in agricultural areas.

Ralph’s “Mobile” Home

Ralph also bought a house. It is the same size as Michael’s and Fred’s. It has a gable roof and rough wood siding. Set on a permanent foundation and landscaped, it looks much like their houses. But Ralph’s house is the third and bottom layer of the manufactured housing cake: it is a “mobile” house, a “doublewide.”

Since June 1976 manufacturing of mobile homes in the United States has come under supervision of the Department of Housing and Urban Development (HUD). Ralph’s house wears the HUD emblem. It signifies that HUD or its “third party” agency is responsible for inspection of the house on the assembly line.

While HUD standards are not the same as the standards for modular houses, at least the standards are uniform everywhere. But while HUD has established a uniform national standard, no state or local authority has to accept the HUD-approved structures. Most cities and counties relegate mobile homes to strictly defined areas such as parks, where lots are rented, or to special subdivisions where lots are sold.

Government Standards for Mobile Homes

The Government (HUD) building requirements might be considered the standard for the third or lower layer of the industrialized housing “cake.” HUD requirements include furnace walls lined with gypsum and fireproof backing behind stoves and exhaust fans. Furnace and water heaters must draw oxygen from outside but emit no gases inside. Smoke and fire detectors are a “must,” as are sliding or open-out windows in bedrooms. Insulation must meet a heat loss-and-gain equivalent of other housing that is qualified for Government-insured financing (FHA, VA, etc.). This means that the HUD-approved mobile home, no matter how small, must lose no more warmth in winter or no more coolness in summer, proportionately, than any other HUD-approved house, no matter how large.

In Europe it is common to see something that resembles a gigantic waffle iron on a railroad flatcar. It is stationed on a railway siding near a building project. The lid is raised, concrete is poured into the “griddle.” After the concrete hardens, a crane lifts out a section of molded floor or wall or roof. The molded section is combined in the construction of buildings as small as houses or as enormous as hospitals, schools and office complexes. The “mobile plant” resolves the problem of trying to transport manufactured buildings from a stationary factory.

In shopping for a manufactured house, remember that current classifications are complex and confusing. The three basic cake “layers” are: (1) The HUD group, which is still mobile housing whether singlewide or doublewide like Ralph’s. (2) The regionally coded group (UBC, BOCA, SBCC)a of multiple-wide modulars like Fred’s, which is often allowed more zoning latitude and easier financing terms. (3) The state-coded group of multiple-wides like Michael’s, which is generally accepted as conventional housing with even more latitude and financing terms.

[Footnotes]

BOCA, established by the Building Officials and Code Administrators International, Inc.

SBCC, established by the Southern Building Code Congress.