Modular buildings (sometimes referred to as  volumetric construction, or prefabricated buildings) are buildings made up of  components  manufactured on assembly lines in factories then assembled on site in a variety of arrangements.

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Buildings can be constructed using modular 'parts' such as walls, frames, doors, ceilings, and windows, or a number of 'complete' prefabricated  modular building units.

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The construction time on site can be reduced by having parts of the structural frame or the building prefabricated as modules. These may be surface units for walls, floors and ceilings or box units with walls, floor structure and ceiling forming one or more rooms.

 

The degree of prefabrication varies; in the most complete units, box units, the surface layer and installations for electricity, telephony, data and plumbing can be pre-installed, so that it all simply needs to be connected on the construction site.

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Walls as surface units often have the same structure as traditional stud walls. They are usually pre-insulated and ready for internal surface treatment. Exterior wall units may also have the final façade cladding fitted and primed. Window frames are generally also pre-installed.

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Surface units are also available as a solid wood structure, with the wall made from a solid sheet of cross-laminated timber (CLT). The wall unit may then be built up around the CLT frame in various ways. The edges are profiled to fit with the floor structure and create a complete, load-bearing system.

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Not only can modular buildings be aesthetically pleasing, but they can also achieve a very high build quality and can be both long lasting and sustainable.

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A new range of modular buildings has emerged that includes a wide variety of sizes and configurations, with sector specific building types and styles, and options for variable plans and multi-storey configurations.

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The gap between modular structures and traditional buildings has narrowed, and there has been an improvement in performance  driven in part by regulatory standards but also by the availability of new materials.