Modular Construction - A Description

Modular construction is a term that is used for the factory production of pre-engineered building units delivered to site and assembled as large volumetric components or as substantial elements of a building. The modular units may form complete rooms, parts of rooms, or separate highly serviceable units such as WC's. Modular units can be a self-supporting structure in their own right or, in the case of skyscrapers; they may rely on the independent structural frame work of the building itself.

The motivation for using modular construction lies in the business-related benefits that make this form of construction more attractive to the client than alternative forms of conventional site-built construction. In such cases, the design decisions are most strongly influenced by:

	Speed of construction on site. Rapid construction leads to business-related benefits to the client, due to early completion and early return on capital investment.
	Avoidance of disruption and loss of operation of adjacent buildings, such as hotels, and in sensitive sites.
	Buildings or components with a high degree of servicing. These require careful site installation, and pre-compliance trials, which are better carried out off site and off the critical construction path.
	A large number of regular or repetitive units. Factory production can facilitate transportation and can achieve economy of scale in production.
	Planning constraints, such as on deliver times, time of working, noise control on site. A short “weather window” or other site constraints to the construction operation.
	Lack of suitable skills at site. This might be the case at a remote site.
	Client requirements for an exceptionally high degree of quality control. This can best be achieved by off-site manufacture and pre-installation checks.
	A requirement for a single point procurement route. This can be achieved through a design manufacture and build service, which the modular industry provides.
	Security or other related issues on site. Construction operations can be controlled more precisely when modular units are used.

 

Modular Units may be used for a wide range of building types from residential buildings to complete fitted-out buildings such as fast food restaurants. Modular construction should be differentiated from temporary or re locatable buildings, which, although similar in volumetric concept, differ greatly in implementation. It is often thought that modular construction is by definition more expensive than traditional construction. While this may be true for “one-off” buildings, there are considerable economies of scale that can be obtained from greater refinement of the design (often by testing) and by investing in mechanized and possible automated production.

The Japanese house building market is dominated by modular construction, and over 150,000 are produced annually in modular form. The high degree of sophistication at the design state permits considerable input by the purchases into the choices of finishes and even into the internal layout. The extremely high cost of land in Japan creates an economic imperative to build quickly and to achieve rapid pay-back, which could not be achieved by a conventional methods of construction.

In the UK , many major companies choose to go the “modular route” because of the greater control they can exert over quality, speed and reliability, which are all business related benefits. Good examples of the move from conventional to modular have been in hotels and fast food restaurants, where on-site construction times can be reduced by over 60%.

Modular construction may be combined with other constructional systems including:

	Framed construction. Modular units can be inserted on the floors or roofs of framed structures constructed of beams and columns.
	Panel construction. Modular units can be used for the more highly services elements, while the remaining structure is built from two-dimensional wall and floor panels.

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