Photograph of  this much-modified trailer - this is not a modern mobile home. It was a camper, converted to use as a house, or perhaps an addition to a house.Definition of:
Modular Construction, Mobile Homes, Campers, Double-Wides, Trailers, Pre-Cut Homes, & Panelized Construction

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Definitions of modular construction, manufactured housing, mobile homes, trailers, campers, doublewides, panelized construction.

What are the differences and how are these structures recognized? This article describes the history and characteristics of these different types of factory-built structures.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Definitions: What is a Mobile Home, Trailer, Doublewide, Modular Home, Factory-Built Home, Panelized-Construction-Built Home?

At ARCHITECTURE & BUILDING COMPONENT ID we included US DOE definitions for the following classes of "manufactured homes":

Manufactured Homes

Manufactured homes are those built entirely in a factory. They are then transported to a building site and installed.

A manufactured home (formerly known as a mobile home) is built to the Manufactured Home Construction and Safety Standards (HUD Code) and displays a red certification label on the exterior of each transportable section. Manufactured homes are built in the controlled environment of a manufacturing plant and are transported in one or more sections on a permanent chassis. - US HUD at

A manufactured home is a single-family dwelling built according to the U.S. Department of Housing and Urban Development (HUD) Manufactured Home Construction and Safety Standards Act, which is a national, preemptive building code. - Washington State Government, (2014)

However the term "manufactured home" is used by different authoritis to include a variety of construction types as we list next.

See MOBILE HOME CODES & STANDARDS for complete details, standards, codes, regulations for manufactured housing & similar constructions

Manufactured homes, in a wider sense include:

Modular Homes

Modules are transported to the site and installed.

See MODULAR HOME CONSTRUCTION for a detailed look at modern modular home construction.

Panelized Homes

Panels—a whole wall with windows, doors, wiring and outside siding—are transported to the site and assembled. See Panelized Construction for a detailed look at a 1950's panelized construction home that was war surplus (Fishkill NY).

Pre-Cut Homes

Building materials are factory-cut to design specifications, transported to the site, and then assembled. Pre-cut homes include kit, dome, and log homes.

LOG HOME GUIDE - provides an example of pre-cut homes, how to inspect, diagnose, and repair problems on log houses; how to identify and determine the age of different types of log homes: traditional log homes, manufactured log homes, slab-sided log homes, and alternative log homes using concrete logs and fiberglass logs.

SEARS KIT HOME IDENTIFICATION provides the most famous example of pre-cut home construction.

Mobile Homes

This is the term used for factory-built homes produced prior to when the HUD Code went into effect.

A mobile home is a factory-built dwelling built prior to June 15, 1976, to standards other than the HUD Code [cited above] that were acceptable under applicable U.S. State Codes (or equivalent in other countries) in effect at the time of construction or introduction of the home into the state. E.g. U.S. Washington State WAC 296-150-M. - Washington State Government, (2014)

See MOBILE HOMES, DOUBLEWIDES, TRAILERS for a detailed look at the wide range of quality and condition of these homes.

See MOBILE HOME ELECTRICAL DEFECTS for examples of differences in building & electrical code requirements depending on the type of construction.

The following is the opinion of the author and has not had a technical review by other industry experts. Various trailer, mobile home, and modular housing manufacturers may disagree with some of these views. Corrections and content suggestions are welcome.

Characteristics of Trailers as Living Space

Tipping trailer home (C) Daniel Friedman

Trailer traditionally describes a usually small, wheeled, home with a history and image of flimsy construction such as wooden 1x3 wall framing clad with aluminum siding, virtually no insulation, and low quality leaky windows.

"Trailers" up until the 1970's (my estimate) included both campers (photo at left) which really were intended to be towed by a car or truck and moved often from site to site (though some were left parked for decades at campgrounds), and also lightweight factory-made homes which were intended to be towed once to a home site and then kept there.

The camper shown in our photo (left) was abandoned but had previously served as a summer camp for many years.

The little blue structure used as an addition to the left of the small house in the photo at the top of this page was undoubtedly a small camper.

No one building "trailers" calls them that any longer because of the "flimsy" image.

Camper Trailer (C) Daniel Friedman

The closest thing to a "trailer" in current products on the market are motor homes and campers such as these campers parked along Wappingers Creek in our photo (left).

The least-costly campers (such as our pickup truck "slide-on camper") built after 2000 are probably considerably better constructed than the "trailers" of old. In current language (2009), a "trailer" is either a "mobile home" that is more than 20 years old (see below), or it is a camper designed to be moved easily and often from site to site.

(Or in different usage, a "utility trailer" is a utility vehicle intended to haul goods or large items and designed to be fastened to the back of a car or truck, and a "tractor trailer" is of course a larger (typically 40 ft long) hauling system for moving goods by highway from city to city.)

Trailers may have had their wheels left on, but normally they'd be set on a masonry pier foundation and a skirt installed around to hide the under-trailer area.

Characteristics of Mobile Homes as Living Space

Mobile home with bad roof (C) Daniel Friedman

In the past few decades (to 2006), "trailer" manufacturers have considerably improved the quality of construction of such homes. The national manufacturing and building code standards for these structures have also been improved.

Perhaps in part to escape the less than wholesome image of "trailer", manufacturers use the term "mobile home" to describe what is usually larger and better made home than "trailers" of old, though perhaps with similar materials.

Mobile homes are built in a factory and are designed to be moved (once and uncommonly, perhaps once again) on its own wheels attached to its own frame to a site where a foundation is prepared and connections to utilities are made.

In the U.S., states have regulations about the siting, foundation, steps and entry, wiring, plumbing, tie-downs for wind and storm safety that apply to these homes. Some examples of mobile home regulations for New York State are this website. Individual state regulations will vary - you'll want to see what your state requires. Even within states regulations vary as wind and weather conditions do also.

Examples of mobile home improvements include stronger overall wall and roof construction, less leaky roof covering, and windows that are less notoriously leaky. In addition newer mobile homes have, for fire safety, bedroom windows that can be pushed out to a wide opening for emergency exit in case of fire - an important safety improvement.

Usually building departments grandfather in older structures, but sometimes they will insist that certain life-safety improvements be made, for example if an older mobile home is being brought to a new site in a new community. If this is the case one or two windows may need to be replaced to provide this important safety improvement.

When there is a severe storm or hurricane, mobile home communities are among the worst damaged as a strong wind can completely turn over or demolish mobile homes. For this reason, mobile homes set up in high wind-risk zones have extra requirements for tie-downs to secure the building against upset during a storm.

Mobile homes may arrive on wheels but they will be jacked enough to be set on some type of approved building foundation, such as masonry piers or a masonry foundation.

In case these terms are not confusing enough, some mobile home makers like to call these "factory built homes". But that use of "factory-built homes" is confusing too since modular homes are also "factory built" but are quite different from trailers or mobile homes.

Characteristics of a "Doublewide" Mobile Home or Trailer

Some manufacturers provide mobile homes constructed to be joined together, side by side to form a double-width living unit.

While a double-wide mobile home is basically constructed by the same materials and methods just described above, the tie-down and connection requirements for these living units may be different in some jurisdictions, since their risk of being blown away in high winds is different.

Other installation and support requirements, such as connection of the two units and placement of foundation support will also have to accommodate this variation.

Modular home construction and inspection are discussed on a separate series of articles beginning at MODULAR HOME CONSTRUCTION.

Characteristics of Panelized Construction

Panelized construction makes use of wall, floor, ceiling or roof "panels" which have been framed off-site and brought to the site by truck. Panels are lifted into place by crane and fastened together on a foundation, and possibly a framed-in floor which have been prepared before the panels arrive.

Some framing panels make use of special materials, such as plywood and foam roof panels for insulated cathedral ceilings

This set of definitions and identifying characteristics of these homes and construction methods is a supplement to our more detailed paper, Mobile Home Inspections.


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DEFINITIONS of MOBILE HOME, DOUBLEWIDE, MODULAR, PANELIZED CONSTRUCTION at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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