Last edited 02 Mar 2021

Modular buildings

Modular buildings (sometimes referred to as volumetric construction, or prefabricated buildings, although strictly speaking, a prefabricated building need not be modular) are buildings made up of components manufactured on assembly lines in factories then assembled on site in a variety of arrangements.

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

Modular building became popular after the Second World War when there was a need for the rapid construction of buildings (in particular dwellings) to replace bomb-damaged buildings and to accommodate returning troops. They were initially well-received, but as they often remained in use well beyond their design life (for example, 'temporary' classrooms, some of which are still in use), and were sometimes aesthetically less attractive that traditional buildings, they fell out of favour.

More recently, there has been a resurgence of interest in modular buildings, with a recognition, not only that they can be aesthetically pleasing, but also they can achieve a very high build quality and can be both long lasting and sustainable.

A new fleet 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.

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. Recent, dramatic examples of the evolution of modular buildings include the 30-storey Tower Hotel in Yueyang and B2, a 32-storey residential tower in Brooklyn, 60% of which was construction off site.

Other examples of modular buildings include:

Educational buildings and nurseries. (See also, Modular buildings in the educational sector.)
Offices.
Temporary buildings (such as site accommodation, live event accommodation, accommodation for temporary re-location during construction works and so on).
Showrooms and marketing suites.
Healthcare buildings (such as consulting rooms, and operating theatres).
Catering buildings.
Ministry of Defence buildings.
Hotels.
Manufacturing facilities such as clean rooms.
Buildings for remote or hostile locations where conventional construction techniques may be impractical.
Dwellings.
Mobile buildings.
Equipment housing.
Emergency buildings for urgent accommodation requirements.
Cruise ship accommodation.

The advantages of modular buildings over more traditional forms of construction include:

Speed of supply and installation.
Reduced cost (through supply chain management, economies of scale, reduction of waste and working in a controlled environment).
Improved quality control (achieved through repetition, inspection and operating in a factory-controlled environment). NB Build quality is increasingly important in achieving environmental standards such as BREEAM. Buildings very often fail to achieve their designed performance because of poor quality control on site.
Reduced time on site.
Reduce disruption, noise and waste.
Reduced need for on-site storage, plant and other equipment.
Reduced labour costs.
Greater control over the full supply chain.
Continuous improvement through an effective feedback loop.
Extendibility.
The potential to de-construct for re-location, re-use or re-sale.

Disadvantages of modular buildings over more traditional forms of construction include:

Restricted flexibility. Module sizes and shapes can be limiting.
Poorer overall design / aesthetic quality.
Design that is not fully context or user specific.
Perception problems resulting from historic performance. This can result in lower valuations.
Difficulty transporting and handling modules.
The significant investment required to develop designs and manufacturing processes for modular buildings.

The supply of modular buildings may simply include manufacture, delivery and installation , or it can be a full 'turnkey' package including site preparation, planning, commissioning, maintenance and even buy-back for re-sale.

NB The BIM Overlay to the RIBA Outline Plan of Work, published by the RIBA in 2012 suggested that volumetric construction: ‘..uses large-scale modular units to construct a building. A building might be formed from one module or from many. Often, units such as bathrooms, plant rooms, lift shafts or services risers are installed within buildings, but do not, of themselves, form the building structure or fabric.’

It defines modular units as: 'Large modules used in volumetric construction. Units such as hotel rooms can be wholly constructed in the factory, as large modules that form the structure of the building as well as enclosing useable space. Units are fully finished internally in the factory, including many aspects of finishes, furnishings and equipment. Increasingly, external cladding, particularly glazing systems, are also installed in the factory, although in some instances finishes such as brickwork are applied on site.'