Modern timber-frame construction in the UK has been developed from North American and Scandinavian methods and bears little resemblance to the traditional, heavy oak-framed buildings of the late Middle Ages. Indeed, most modern timber-frame houses, when built, are visually indistinguishable from their brick and block counterparts. Modern timber-frame construction is based on off-site prefabrication and typically has the roof, the internal and external walls, the first floor and, often, the ground floor built in a factory and then transported to site for assembly.
Although it is not difficult to find examples of ‘modern’ timber framing from the first part of the twentieth century, it did not become a popular form of construction until the 1960s. By the beginning of the 1980s, some 20 per cent of new houses were timber framed, but adverse publicity about quality and construction methods reduced this percentage considerably during the middle of the decade. Since the 1990s, improved design and more rigorous quality control have helped to reinstate the image, and the popularity, of timber-frame housing. The trend by successive governments to encourage the construction industry to adopt prefabrication techniques, such as modern methods of construction (MMC) – see Chapter 1 – as a means of improving quality and avoiding the problems of skills shortages has also given a boost to timber- frame construction. For the past few years, the share of timber-frame construction in the UK housing market has been about 25 per cent.
Timber-frame construction offers several potential advantages for developers over traditional brick and block forms of building. These include:
- faster construction (producing a quick return on borrowed capital and less financial risk) – on-site construction is reduced because of the prefabrication that takes place in the factory. There is also a time advantage because a relatively weathertight building can be formed in a few days and this allows internal work to start quickly. In addition, there is no time lost waiting for the mortar to dry out (as would be the case with masonry) and freezing conditions will not affect site erection (unless an external masonry skin is added)
- less dependence on traditional ‘wet’ skills, such as bricklaying and plastering
- less costly due to the greater use of unskilled site labour
- reduced dead-load resulting in lighter and cheaper foundations.
In addition, timber-frame construction can be relatively easily adapted to encompass high levels of thermal insulation.
Timber-frame construction offers the potential for greater quality control, in so far as this is potentially easier to achieve in factory conditions rather than on site. However, even where stringent factory quality control checks are in place, there may be installation deficiencies in relation to important details, such as vapour control layers, fire stops and cavity barriers, etc. and, therefore, good site management and control is essential. Prefabrication off-site also requires accurate setting out on site – if components do not fit properly, quality may be compromised.
