Prefabricated homes, often referred to as prefab homes or simply prefabs, are specialist dwelling types of prefabricated building, which are manufactured off-site in advance, usually in standard sections that can be easily shipped and assembled. Some current prefab home designs include architectural details inspired by postmodernism or futurist architecture.
"Prefabricated" may refer to buildings built in components (e.g. panels), modules (modular homes) or transportable sections (manufactured homes), and may also be used to refer to mobile homes, i.e., houses on wheels. Although similar, the methods and design of the three vary widely. There are two-level home plans, as well as custom home plans. There are considerable differences in the construction types. In the U.S., mobile and manufactured houses are constructed in accordance with HUD building codes, while modular houses are constructed in accordance with the IRC (International Residential Code).
Mobile homes and manufactured homes can be placed in mobile home parks, and manufactured homes can also be placed on private land, unless the land is within a subdivision whose CC&Rs prohibit manufactured housing.
Constructing manufactured homes typically involves connecting plumbing and electrical lines across the sections, and sealing the sections together. Manufactured homes can be single, double or triple-wide, describing how many sections wide it is. Many manufactured home companies manufacture a variety of different designs, and many of the floorplans are available online. Manufactured homes can be built onto a permanent foundation, and if designed correctly, can be difficult to distinguish from a stick-built home to the untrained eye.
Manufactured homes are typically purchased from a retail sales company, initially assembled by a local contracting company, and follow-up repairs performed by the manufactured home company under warranty.
A manufactured home, once assembled, goes through a ‘settling-in’ period, where the home will settle into its location. During this period, some drywall cracking may appear, and any incorrectly installed appliances, wiring or plumbing should be repaired, hopefully under warranty. If not covered under warranty, the costs will be borne by the consumer. For this reason, it is important that the consumer ensure that a reputable and honest contractor is used for the initial set-up. If any repairs are not completed by the initial set-up crew, the manufacturer will send repair crews to repair anything covered by the warranty. The secondary repair team must be scheduled, and may not be available immediately for most repairs. Just because a manufactured home has been assembled does not mean it is immediately habitable; appropriate ventilation, heating, plumbing, and electrical systems must be installed by a set-up crew, otherwise, the buyer must wait for the manufacturer repair team or do it themselves.
The word ‘prefab’ is not an industry term like modular home, manufactured home, panelized home or site-built home. The term is an amalgamation of panelized and modular building systems, and can mean either one. In today's usage the term ‘prefab’ is more closely related to the style of home, usually modernist, rather than to a particular method of home construction.
The first mention of a prefabricated building was in 1160 to 1170 by Wace as confirmed by Pierre Bouet. In the special May/June 2015 edition of the French magazine Historia, he spoke of a castle transported by Normans in 'kit' form. According to Bouet, Wace's epic poem Roman de Rou, verses 6,516–6,526, states: "They took out of the ship beams of wood and dragged them to the ground. Then the Count (Earl) who brought them, (the beams) already pierced and planed, carved and trimmed, the pegs (raw-plugs/dowels) already trimmed and transported in barrels, erected a castle, had a moat dug around it and thus had constructed a big fortress during the night."
Wooden homes have always been popular in North America, due to the large quantity of timber available in North America. In the United States, several companies including Sears Catalog Homes began offering mail-order kit homes between 1902 and 1910. The Forest Products Laboratory, a division of the U.S. Forest Service, put extensive research into prefabricated homes in the 1930s, including building one for the 1935 Madison Home Show. This research continued into the 1960s.
By 1958, roughly 10 percent of new houses in the United states were prefabricated.
In the United Kingdom, more than 156,000 prefabricated homes were built between 1945 and 1948.
After the World War II until 1948, Sell-Fertighaus GmbH built over 5,000 prefabricated houses in Germany for the occupying force of the United States.
There is no pan-EU housing standard for this kind of home construction, and regulation is at the national level. EU directives that apply to housing construction and design do not directly affect the modular home sector. However, each modular home must comply with EU's Eurocodes and local building codes.
In the United Kingdom the word ‘prefab’ is often associated with a specific type of prefabricated house built in large numbers after the Second World War, such as Airey houses, as a temporary replacement for housing that had been destroyed by bombs, particularly in London.
Despite the intention that these dwellings would be a strictly temporary measure, many remained inhabited for years and even decades after the end of the war. A small number are still in use in the 21st century, but more and more are being demolished. In 2011 it was announced that Britain’s largest remaining prefab estate of 187 homes in Lewisham, South-East London, is to be redeveloped except for six homes.
The latest iteration of the idea is a development of 36 apartments called y:cube made by the YMCA in Mitcham, South London Ilke Homes in Knaresborough constructs 2 and 3 bedroom 'modular' homes that can be erected in 36 hours.
In 2010, Bali exported 98,417 prefabricated houses, but in 2011 the region only exported 5,007 units due to the global economic slowdown that affected a number of export destinations. These Balinese prefab houses are well known for their artistic design and practical value.
Prefab homes are becoming popular in Europe, Canada and United States as they are relatively cheap when compared to many existing homes on the market. The 2007 finance crisis has however deflated the cost of housing in North America and Europe, so not all prefab homes should be assumed to be cheaper than existing housing.
Modern architects are experimenting with prefabrication as a means to deliver well-designed and mass-produced modern homes. Modern architecture forgoes referential decoration and instead features clean lines and open floor plans.
Because of the design simplifications modern architecture provides (coupled with the cost savings that tend go with design simplification) many in the manufactured housing sector generally feel that modern architecture designs are better suited for prefab home construction.
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