Editing Prefabrication (section)

==Process and theory==
[[File:Levittown, Puerto Rico.jpg|thumb| [[Levittown, Puerto Rico]]]]
An example from house-building illustrates the process of prefabrication. The conventional method of building a house is to transport [[brick]]s, [[timber]], [[cement]], [[sand]], [[steel]] and [[construction aggregate]], etc. to the site, and to construct the house on site from these materials. In [[Prefabricated buildings|prefabricated construction]], only the [[foundation (architecture)|foundation]]s are constructed in this way, while sections of [[wall]]s, floors and [[roof]] are prefabricated (assembled) in a factory (possibly with window and door frames included), transported to the site, lifted into place by a [[crane (machine)|crane]] and [[bolt (screw)|bolt]]ed together.

Prefabrication is used in the manufacture of [[ship]]s, [[aircraft]] and all kinds of [[vehicle]]s and [[machine]]s where sections previously assembled at the final point of manufacture are assembled elsewhere instead, before being delivered for final assembly.

The theory behind the method is that time and cost is saved if similar construction tasks can be grouped, and [[assembly line]] techniques can be employed in prefabrication at a location where skilled labour is available, while congestion at the assembly site, which wastes time, can be reduced. The method finds application particularly where the structure is composed of repeating units or forms, or where multiple copies of the same basic structure are being constructed. Prefabrication avoids the need to transport so many skilled workers to the construction site, and other restricting conditions such as a lack of power, lack of water, exposure to harsh weather or a hazardous environment are avoided. Against these advantages must be weighed the cost of transporting prefabricated sections and lifting them into position as they will usually be larger, more fragile and more difficult to handle than the materials and components of which they are made.