The landscape of the housebuilding industry is changing: timber frame construction is returning to favour among developers in England after many years lost in the wilderness. Its market share is now a respectable 11% which, given that total housebuilding output is 170,000 units per year, represents a sizeable industry.
The Scots still build 70% of their houses using timber frame so it is no surprise that Britain’s largest timber frame manufacturer is the Aberdeen-based Stewart Milne Group. Founded in 1975, the group now has 1,100 employees, a turnover of £217m and a factory in Witney, Oxfordshire, the starting point for the group’s ambitious plans to penetrate the English market.
The Stewart Milne Group has three divisions dealing with development, timber systems and construction and is the only timber frame company that enjoys this breadth of integration. The factory in Oxfordshire is the latest investment of Stewart Milne Timber Systems (SMTS), complementing its established operation in Westhill, Aberdeen. The joint output is around 8,000 houses per year, of which 5,000 are destined for Scotland. By 2010, the company aims to increase output to the English market from 3,000 to 6,500 houses.
Does such ambition have strong commercial foundations? SMTS managing director Stewart Dalgarno has no doubts: “There are many factors currently improving the viability of timber frame over brick and block construction,” he said. “Timber frame is well-suited to off-site manufacture, it has an excellent environmental profile and can adapt to tougher Part L requirements without difficulty. It is, however, the price competitiveness of timber frame that is really driving change.”
Dalgarno cites an impeccable source to back up such claims: the National Audit Office’s report “Using modern á Ü methods of construction to build homes more quickly and efficiently”. This includes an analysis of the relative costs of timber frame and brick and block over different build sizes. For buildings of five storeys or more, timber frame has a clear cost advantage because of the additional engineering required for brick and block at this height. At three or four storeys, timber frame has a modest cost advantage and at one or two storeys the two methods of construction are effectively cost competitive. Not surprisingly, Stewart Milne has been building a lot of apartment blocks in recent years. The challenge now is to get the edge over traditional brick and block in the low-rise housing market.
SMTS’s Oxfordshire factory is an impressive attempt to meet this challenge. Extensively automated, the production line can turn out the structural envelope of a timber frame house every 40 minutes. There are only 30 people on each shift who transform studs, I-beams and plywood into floor and wall cassettes, ready for transport and quick erection on site. The flow lines are carefully co-ordinated to ensure a smooth throughput and are flexible enough to respond quickly to different design specifications.
Currently the factory produces open-panel structural shells but plenty of space has been set aside for more advanced products, as and when the volume market demands them. In the next year the company plans to introduce factory-
fitted windows and doors, new acoustic floor cassettes and unserviced closed panel walls. Looking further ahead, there will be a room-in-roof cassette system, serviced closed panels and single skin construction.
Raw materials are imported from PEFC- and FSC-accredited sources in Sweden and Finland where the mills turn their waste streams into paper pulp or energy. Similarly, at Witney, wood waste is turned into chipboard or sent to a biomass energy plant in Slough. The Oxfordshire factory is currently heated by gas but the company is planning a conversion to wood-burning to reduce its utilities bill.
Off-site integration, lean production, technical innovation and resource efficiency all help SMTS to sell its product at a competitive price but Dalgarno knows all too well that there are other obstacles, well beyond the factory walls, that he must also overcome. His primary aim is not to take business from other timber frame manufacturers, though he may well do this, but rather to take market share from brick and block. Given the extraordinary difference between the two construction methods and the entrenched position of brick and block in the English market, he must change attitudes, knowledge and processes as well as materials and design.
Partnership and knowledge-sharing are the buzzwords at the heart of SMTS’s business. In practice this means working with clients at every stage of the job, from concept drawings and design development through specification and pricing to delivery, erection and handover. Only a fully-integrated process will reassure new clients that they are getting not only the product they want but also the service levels they need.
The perception that brick and block is the cheap option is beginning to fade, according to Dalgarno. Developers’ margins are being squeezed by rising costs for land, energy and labour and slower house inflation. Skills shortages are making off-site construction more and more attractive. New insulation and airtightness standards increase the pressure on the profit margin. The building industry may have a reputation for conservatism but, when money talks, everyone listens.
Timber frame has long ceased to be a cottage industry. Or rather, it has long ceased to be entirely a cottage industry – there are still plenty of small firms doing good work with self-builders and specialist developers, often using traditional techniques and materials such as green oak frame. The slick, automated Oxfordshire model is a world away from such methods but it is no less inspiring. Off-site timber frame manufacture offers a means of using sustainable materials to produce high performance buildings for the mass market. Given the size of this market and the increasing importance of building to exceptional thermal standards, it seems likely that timber frame will take an ever more prominent place in the landscape of Britain.
