Timber frame has a great story to tell – but more people have to hear it if this form of construction is to realise its full potential. That was one of the messages to emerge from a recent seminar at Stirling University: “Opportunities for timber in Scottish affordable housing”.
Centrepiece of the event was a presentation from Dr Douglas Robertson of the host university’s housing policy and practice unit in which he summarised the findings of a study addressing opportunities and perceived barriers to the use of timber frame in regeneration projects. Based on surveys and interviews with key players in housing association development work, the research team had concluded that timber frame was seen as acceptable for one- and two-storey properties, “but less so for three storeys,” he stated. “And above that height, it is not really countenanced.”
According to Dr Robertson, concerns about height were based largely around differential movement, shrinkage and acoustic transfer. This was despite the fact that BRE work had tested the performance of six-storey timber frame buildings against English and Scottish regulations without finding any difficulties. If technical problems of the past had been overcome “there is clearly an educational issue that needs to be addressed by the timber frame industry,” he said.
In order to illustrate the technical advances of recent years, Dr Robertson suggested Communities Scotland should consider funding a four-, five- or six-storey timber frame development. His report summary added: “The timber frame industry previously only really engaged with builders and contractors. It is crucial that [the industry] starts to engage directly with housing associations, architects and policy makers.”
He said cost and “a more predictable development period” had helped to propel timber frame to its position as the core construction method for Scottish house building, and he believed sustainability “could quickly become a new driver”. However, specific targets rather than often “tokenistic” statements about sustainability could encourage greater innovation, he added.
Dr Robertson also reflected a common view among study participants that there were opportunities to encourage greater use of home-grown timber for particular elements within timber frame kits. “The point was made that there is no technical requirement to have the kit made entirely of C24 structural strength graded timber,” stated the study summary. Dr Robertson added that housing associations were largely “ignorant” about the sourcing of timber and about the fact that “Scottish suppliers do not necessarily stock Scottish-sourced timber”.
Strong growth predicted
UK Timber Frame Association (UKTFA) chief executive Bryan Woodley predicted strong growth not only in the Scottish timber frame market in general but also specifically in the area of social housing. According to association figures, the timber frame market in Scotland amounted to 17,223 units last year compared to 15,405 in 2003, while the social housing total had risen from 3,315 to 3,415. UKTFA estimates that, by 2007, the medium-rise timber frame total for Scotland will be 22,936 units, of which social housing will account for 4,502.
Mr Woodley emphasised that the timber frame production sector was “in a very good position to fulfil the affordable housing needs of Scotland” and that growth could outstrip current expectations “if the government fires in more money”. He insisted that the key to more rapid growth was the funding mechanism rather than changes to Building Regulations – one of the options put forward by Dr Robertson.
From the wider UK perspective, timber frame’s share of the new housing market had soared from 8.4% as recently as 1998 to 17% in 2004, according to Mr Woodley. Growth in England had been particularly strong: from just over 15,000 units in 2003 to 18,338 units the following year.
Mr Woodley identified the following reasons behind the growing appeal of timber frame: speed of construction; good sustainability and environmental credentials; fewer calls-back; and design flexibility. In the future, he envisaged “even higher levels of engineered precision” and an increase in “hybrid” systems, as well as greater uptake of higher-rise timber frame construction. “There is one seven-storey building in Bristol but five- and six-storeys are becoming increasingly common,” he said. “I really believe multi-storey is on the up.”
Other industry speakers at the seminar were equally upbeat about the prospects for timber frame. Alistair Wylie, managing director of Glasgow-based Campbell Construction Group, underlined the massive benefits for housebuilders of constructing much of a timber frame building indoors, thereby avoiding the vagaries of the British weather. He added that advances in engineered wood had helped to overcome reservations about using home-grown timber.
Mr Wylie closed with the thought: “Traditional site skills need to develop to accommodate the advances in timber frame construction.”
Greater market share
According to Alex Goodfellow, managing director of Aberdeen-based Stewart Milne Timber Systems (SMTS), his company had already built more than 2,500 flats and 1,200 bedrooms for timber frame buildings of five-, six- and seven-storeys. By 2010, he confidently predicted, timber frame will have secured market shares of 30% and 70% in, respectively, England and Scotland, by which time SMTS expects to have opened a third timber frame construction factory to add to its existing two facilities in Aberdeen and Witney.
Despite the technical progress already made in timber frame, companies were continuing to invest heavily in research and development, according to Mr Goodfellow. For example, SMTS was trialling a new wall panel while Larbert-based James Jones & Sons Ltd was looking at using I-Joists in roof panels. The latter’s director Tom Bruce-Jones said tests had indicated that roofs could be made wind- and watertight in two-and-a-half hours.
James Jones’ joint managing director John Kissock countered any suggestion that home-grown timber was not available in sufficient quantity by observing that, after Sweden, the UK was the second-largest supplier of timber into its own home market.
