Demountable

A portable, demountable or transportable building, is a building designed and built to be movable rather than permanently located. A common modern design is sometimes called a modular building, but portable buildings can be different in that they are more often used temporarily and taken away later. Portable buildings (e.g. yurts) have been used since prehistoric times.

The most familiar modern type of portable buildings are designed so that one can be carried to or from site on a large lorry and slung on and off by a crane.

The modern portable building, or "knock-down" building, was first developed by United States firm Porta-Kamp in 1955. The first portable building under the trade name Portakabin was developed in 1961 in York (UK) by Donald Shepherd.

Portable modular buildings have various uses. They are often seen, alone or in groups, as temporary site offices on building sites (where they are often stacked two high with metal stairs to reach the upper level; see also Construction trailer). Other uses for these and other types of portable buildings are as guard shacks, in-plant offices (these are typically portable steel buildings), rural offices, on-site changing rooms, etc. Some portable buildings are very complex by joining units these forming large office blocks. (even over several floors). These are often disguised as a normal building often with brick style cladding and a traditional pitched roof. Tara Park developed by Liverpool City Council have even used portable buildings to create temporary/permanent domestic housing for communities complying with UK building regulations and disabled access.

Due to population increases in many areas, portable buildings are sometimes brought in to schools to provide relief from overcrowding. Portable classroom buildings often include two classrooms separated by a partition wall and a toilet. Portable buildings can also serve as a portable car garage or a storage unit for larger items. Businesses will often utilize portable buildings for bulk storage or construction equipment.

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