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Glossary of terms

If you’re new to manufactured homes it’s easy to be confused by the different terms you will hear. Here’s are some definitions to help you better understand what these homes are—and what they are not.

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BOCA Code Home (Michigan)

In Michigan, state pre-manufactured (modular) homes are designed, built and regulated to adhere to the State of Michigan Residential Building Code. State pre-manufactured homes are often referred to as BOCA Code homes, but this is an outdated term. Since July 2001, Michigan has mandated one state-wide building code that is, for the major part, the same as the international code, and properly called the State of Michigan Residential Building Code. Building Officials and Code Administrators International, Inc. is the oldest of three "model" codes used in the United States. Site-built and modular homes previously fell under this code, which is still used by states in the Midwestern and Eastern parts of the country. Modular homes may be one- or two-story dwellings and are placed only on private property.

DAPIA (Design Approval Primary Inspection Agency)

Under the HUD Code, the DAPIA is the organization that reviews the manufacturer's complete drawing and engineering package for each home plan. If the engineering calculations demonstrate that the home will meet the HUD Code's performance standards, the DAPIA issues a plan approval to the manufacturer, which is the factory's authority to build and sell the home. This is the manufactured housing industry's equivalent to the local building department's plan-checking function.


A projecting structure built out from a sloping roof, usually including one or more windows.


The portion of a roof projecting past the exterior walls.

Factory built home

Any home that is constructed inside a factory and then brought to the site in big pieces, usually sections or modules, and assembled. This is a pretty broad term: manufactured homes, mobile home and modular homes are examples of factory built home.

Fastener Plate

Braces of heavy sheet metal used in some manufactured homes to bolt finished walls to the subfloor frame.

HUD (United States Department of Housing and Urban Development)

HUD has jurisdiction over the manufactured housing industry, but not modular homes, whose construction is governed by the individual states.

HUD Code

The informal name for the National Manufactured Home Construction and Safety Standards.

HUD-Code home

Same as a manufactured home.


The protection of a structure from heat loss by filling wall, roof and floor voids with materials that retard heat flow.

Manufactured Home

Simply defined, a manufactured home is a complete dwelling unit designed for year-around-living, and substantially constructed in a factory in conformance with a national building code developed in 1976 by the U.S. Department of Housing and Urban Development (HUD). The home can consist of one or more transportable sections, each constructed on an integral permanent steel chassis (frame) to which are attached axles, wheels, brakes and a hitch. Each complete section is then hitched to a tractor trailer and towed from the factory to a retail sales lot or to a home site. Once a home is placed on its site, usually on jack stands or blocks, the wheels and running gear are removed and recycled back to the factory. The home is then tied to the foundation (well , it’s supposed to be but enforcement varies widely) and skirting is installed around the perimeter to enclose the space beneath the home.
The key distinction here is the home is towed to its site on its own wheels. A second distinction is “manufactured home,” at least technically, refers to any such home constructed after June, 1976 when the Federal Manufactured Home Construction Safety Standards, called the HUD Code, went into effect. All such homes built prior to this date are officially called mobile homes.

Manufactured Home Community

Private land developed as home sites for manufactured homes. In most areas, most sites are leased to the homeowner for a monthly fee. Sometimes referred to as a land-lease community.

Multi-section Home

A manufactured home delivered to the home site in two or three sections. The average square footage is 1,715 square feet, but may be as large as 2,400. May have a (site-built) garage attached after the home is installed.

Mobile home

Technically, any manufactured home built prior to June, 1976 (see above). There are still hundreds of thousands of these antiques still around, many of them poorly engineered, and shoddily constructed with cheap materials before governmental regulators stepped in. Many others, built to a higher standard and well maintained, are still going strong. Alas, the term “manufactured home” has never really caught on with the public, and nearly everyone outside the industry still calls them mobile homes, even the New York Times and the Wall Street Journal. Some people still call mobile homes house trailers. As one industry wag once proclaimed, “We don’t build house trailers any more, we build manufactured trailers.”

Modular home

A factory built home constructed of prefabricated three-dimensional modules, entire rooms and larger, which are transported on flat-bed trucks to a home site and assembled, usually using a crane for placement. Sometimes the module is jacked up and the flat bed truck is then driven out from beneath it. A key distinction: modular home components don’t have wheels and running gear and are not towed to the home site. Two other characteristics to keep in mind: 1., most modular homes are built in conformance with the Uniform Building Code, or other local code requirements, not the HUD code. And, 2., Modular homes (with very few exceptions) are more costly than manufactured homes while offering savings over comparable site built homes (from which they are usually indistinguishable in appearance). In fact, modular construction is steadily gaining popularity for high end luxury homes because of its cost savings and shorter construction time.


A mortgage is the actual legal document by which real property is pledged as security for the repayment of a loan, but generally speaking the word “mortgage” encompasses several different loan options for purchasing or refinancing a home or tapping in to your home’s equity.

Off site built home

Another term for factory built, sometimes used to avoid having to use the term manufactured home with its connotation of mobile home.

Panelized homes

Homes that are constructed of largely complete (or closed) panel sections. For example, a wall panel could consist of windows, a door, all the inside wiring, and insulation, its interior side covered with gypsum (dry wall), its outside with exterior siding. The finished panels are then transported to the building site, together with floor and roof panels, and assembled, usually with the help of a crane. An alternative system uses open panels in which the interior is left open for on-site installation of wiring, insulation, etc. Built to local codes. Note: The use of panelized sections is a growing trend among big home builders who develop large subdivisions of site-built homes. In essence these homes are hybrids: built on site using many large components (panel section, roof trusses, etc.) made in a factory.


The degree of slope in a roofline, expressed in inches of vertical rise per foot (12 inches) of horizontal run. For example, a pitch of 4/12 means that for each horizontal foot the roof rises four inches.


Wood sheeting consisting of three or more layers of veneer joined with glue. The alternate layers, or "plies," usually are arranged with grain running at right angles for added strength.

Pre-cut homes

Essentially kit homes in which all the lumber and other materials are measured and pre-cut at the factory, then transported to the site and assembled by the builder. Packages may include many more building materials such as pre-hung windows and plumbing. Homes in this category can be very high end. Also included here are log homes, A-frame homes and domes. All are built to local codes.

Property, personal and real

Manufactured homes sold independently of the land on which they will be placed are classified as personal property. Homes that are permanently affixed to the land on which they are located through a foundation system are classified as real property.


Licensed, professional seller of manufactured homes. Assists in arrangement for financing, and has home installed on home site and prepared for move-in.


Materials of various sizes and types (often wood or fiberglass-asphalt composition) used to cover roofs and exterior sidewalls.

Site-built home

Any home that is built on the site, which the vast majority of homes are.

Single Section home

A manufactured home delivered to the home site in one, intact section; the average square footage is 1,120 square feet.


The underside of the eaves of a roof.

Stick-built home

Same as a site-built home, although the term is inaccurate. Factory built homes are also stick-built; the “sticks” (lumber) are simply assembled inside a factory.


Upright wall-framing member of wood or steel to which wall covering and exterior sheathing is applied.


Plywood, OSB (oriented strand board), or particle board sheathing attached directly to the subfloor frame (joists or trusses) prior to installation of underlayment and finished floor.

Subfloor Fram

A frame constructed of dimension lumber containing heating ducts and other utility lines, as well as insulating material. In many manufactured homes, this is the first factory-built assembly of the unit.


Pre-assembled, bow-shaped or triangular frames used in roof construction.


Plywood or other material, usually applied over a rough subfloor, to serve as a smooth surface for carpeting or flooring.

Vapor Barrier

Plastic film, building paper, paint, or other material used to retard flow of moisture. Often applied after installation of insulating material to prevent moisture from entering the insulation and thus diminishing its effectiveness. Some insulation incorporates its own vapor barrier.

Vaulted Ceiling

Arched, pitched or concave (barrel-shaped) ceiling design often incorporated to enhance the spaciousness of a room.