Mobile homes or static caravans are housing units built in factories, rather than on site, and then taken to the place where they will be occupied. They are usually transported by tractor-trailers over public highways. They are less expensive per square foot than site-built homes, and are often associated with rural areas and high-density developments, sometimes referred to as trailer parks. In the UK and USA they are at times referred to as "mobile home parks".
The term "manufactured home" specifically refers to a home built entirely in a protected environment under a federal code set by the US Department of Housing and Urban Development (HUD). Contrary to popular belief, manufactured homes are not mobile homes. The term "mobile home" describes factory-built homes produced prior to the 1976 HUD Code enactment.
These houses are usually placed in one location, often a rented lot, and left there permanently. However, they do retain the ability to be moved, as this is a requirement in many areas. Behind the cosmetic work fitted at installation to hide the base, there are strong trailer frames, axles, wheels and tow-hitches.
Manufactured homes are not large recreational vehicles. The latter are more properly called travel trailers, motor homes or RVs, and they are usually parked at facilities called trailer parks, trailer courts, or RV parks for short terms.
The two major forms of manufactured homes are single-wides and double-wides. Single-wides are sixteen feet or less in width and can be towed to their site as a single unit. Double-wides are twenty feet or more wide and are towed to their site in two separate units, which are then joined together. Triple-wides and even homes with four, five, or more units are also manufactured, although not as commonly.
In the U.S., manufactured homes are regulated by the United States Department of Housing and Urban Development (HUD), via the Federal National Manufactured Housing Construction and Safety Standards Act of 1974. It is this national regulation that has allowed many manufacturers to distribute nationwide, since they are immune to the jurisdiction of local building authorities. By contrast, producers of modular homes must abide by state and local building codes. There are, however, windzones adopted by HUD that manufactured home builders must follow. For example, state-wide, Florida is at least windzone 2. South Florida is windzone 3, the strongest windzone. After Hurricane Andrew in 1992, new standards were adopted for manufactured home construction. The codes for building within these windzones were significantly amended, which has greatly increased their durability. During the 2004 hurricanes in Florida, these standards were put to the test, with great success.
However, older models continue to face the exposed risk to high winds due to the attachments applied such as carports, porch and screen room additions. These areas are exposed to "Wind Capture" which apply extreme force to the underside of the integrated roof panel systems, ripping the fasteners through the roof pan causing a series of events which destroys the main roof system and the home.

History
In the UK there are three main types of mobile home: touring caravans, static caravans, and motorhomes. A touring caravan is towed behind a car to its site and parked, often for only a brief period. Touring caravans are usually no larger than 10'x16' (3.048 m x 4.87 m) and can have 1 or 2 axles (2 or 4 wheels respectively). Static caravans aren't generally towed, as they are too large to tow, sometimes up to 40'x13' (12.19 m x 3.96 m), and therefore are transported on the back of large flatbed lorries. A static caravan will normally stay on a single plot for many years, and have many of the modern conveniences one would normally find in a home.
Motorhomes are similar in size to touring caravans but with one main difference: they have engines and do not need to be towed. Motorhomes can have many modern conveniences such as showers and full-sized cookers. Motorhomes are for all intents and purposes full touring caravans that can be driven from site to site.

Types of mobile homes in the United Kingdom
The rise of the manufactured home brought with it complications the legal system was not prepared to handle. Originally, manufactured homes tended to be taxed as vehicles rather than real estate, which resulted in very low property tax rates for their inhabitants. This led local governments to reclassify them for taxation purposes.
However, even with this change, rapid depreciation often resulted in manufactured home occupants paying far less in property taxes than had been anticipated and budgeted. The ability to move many manufactured homes rapidly into a relatively small area resulted in strains to the infrastructure and governmental services of the affected areas, such as inadequate water pressure and sewage disposal, and highway congestion. This led jurisdictions to begin placing limitations on the size and density of developments.
As noted above, early manufactured homes, even those that were well-maintained, tended to depreciate in value over time, much like motor vehicles, rather than appreciate in value, as with site-built homes. The arrival of manufactured homes in an area tended to be regarded with alarm, in part because of devaluation of the manufactured housing potentially spreading to preexisting structures.
This combination of factors has led most jurisdictions to place zoning regulations on the areas in which manufactured homes are placed, and limitations on the number and density of manufactured homes permitted on any given site. Other restrictions, such as minimum size requirements, limitations on exterior colors and finishes, and foundation mandates have also been enacted. There are many jurisdictions that will not allow the placement of any additional manufactured homes. Others have strongly limited or forbidden all single-wide models, which tend to depreciate in value more rapidly than modern double-wide models.
Apart from all the practical issues described above, there is also the constant discussion about legal Fixture and chattels - meaning that the legal status of a trailer is, or could be, affected by its incorporation to the land or not.

Legal complications
In the past, manufactured home parks have, often with legitimate reason, been thought of as substandard. With more modern manufactured home parks however, this is not the case. Most have regulations concerning the size and styles of homes permitted, and many are somewhat similar to more traditional subdivision developments. In some of the more satisfactory parks, all of the homes are owned by the individual occupants. Only the spaces or pads are rented, not the units themselves. Developments in which the buyer purchases both the home and the lot are almost indistinguishable from traditional subdivisions. In lower-end parks, some or all of the units are owned by the operators of the park and are rented to occupants. These developments are considered undesirable by property owners because they are known to depreciate the value of surrounding property.
Newer manufactured homes, particularly double-wides, tend to be built to much higher standards than their predecessors and meet the building codes applicable to most areas. This has led to a reduction in the rate of value depreciation of most used units.
Additionally, modern manufactured homes tend to be built from materials similar to those used in site-built homes rather than inferior, lighter-weight materials. They are also more likely to physically resemble site-built homes. Often, the primary differentiation in appearance is that manufactured homes tend to have less of a roof slope so that they can be readily transported underneath bridges and overpasses.
The number of double-wide units sold exceeds the number of single-wides, which is due in part to the aforementioned zoning restrictions. Another reason for higher sales is the spaciousness of double-wide units, which are now comparable to site-built homes. Single-wide units are still popular primarily in rural areas, where there are fewer restrictions. They are frequently used as temporary housing in areas affected by natural disasters, when restrictions are temporarily waived.

Manufactured home parks
Manufactured homes are often confused with but are not identical to modular homes. Modular homes are transported on flatbed trucks rather than being towed, and lack axles and an automotive-type frame typical of manufactured homes. However, like manufactured homes, some modular houses are towed behind a semi-truck on a frame similar to that of a manufactured home. The house is usually in two pieces and is hauled by two separate trucks. Each frame has five or more axles, depending on the size of the house. Once the house has reached its location, unlike a manufactured home, the axles and the tongue of the frame are then removed, and the house is set on a concrete foundation by a large crane.
Both manufactured homes and modular homes are commonly referred to as manufactured housing, although its technical use is restricted to a class of homes regulated by the Federal National Manufactured Housing Construction and Safety Standards Act of 1974.
Most zoning restrictions on manufactured homes have been found to be inapplicable or only applicable to modular homes. This occurs often after considerable litigation on the topic by affected jurisdictions and by plaintiffs failing to ascertain the difference. Most modern modular homes, once fully assembled, are indistinguishable from site-built homes. Their roofs are usually transported as separate units, eradicating the telltale roofline of the manufactured home. As the legal differentiation between the two becomes more codified, the market for modular homes is likely to grow.
The traditional manufactured home industry would seem to have a bright future as well. As the demand for housing continues to grow, the price of housing continues to increase rapidly. The quality and features of manufactured homes has led to greater acceptance by a growing segment of the marketplace. Additionally, insurers and lenders are now more likely to treat the higher-end manufactured home as they would a traditional home.

Manufactured homes and tornadoes
In 2005, a neighborhood of about 500 manufactured homes was established in Nitzan. This was a temporary community set up north of Ashkelon, Israel, to house those evacuated from their homes in Gush Katif as part of Israel's unilateral disengagement plan.
These manufactured homes were named caravillas (Hebrew: קרווילה), which is a portmanteau of the words caravan, and villa. The building is composed of several prefabricated sections, similar to those of a manufactured home, that are joined on a foundation. This is akin to the Israeli concept of a villa, or Single-family home. The caravilla is more spacious than a regular manufactured home, and was instrumental in pacifying objections to the Disengagement plan.

Trivia

HUD USER
Regulatory Barriers Clearinghouse
Manufactured housing