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North south divide
Autumn 2008
Published:  01 December, 2008

Scotland has proved fertile ground for timber frame construction. Mike Jeffree reports on why

Scotland 68, England 14. No that’s not, a fantasy score for a Scottish rugby supporter. It’s the percentage of new house building accounted for by timber frame construction in the two countries.

A number of explanations have been suggested for this market share disparity.  One is that Scotland has more forest and is a generally more timber-oriented economy. Some   put it down to the weather. The country’s prime building ‘season’ is that much shorter than England’s, so, it’s argued, the speed at which timber framed houses can be made water and wind-tight has added appeal.

But while both factors may have sowed some seeds, what has really fired growth, according to timber frame suppliers, is that Scottish builders have absorbed timber frame construction methods into their DNA. To maximise the potential cost and efficiency benefits, they’ve adapted their whole approach, from site planning and logistics, to work practices, even job demarcation. 

According to the UK Timber Frame Association (UKTFA), there are builders in England and Wales, including its members, who have developed in the same way and become sawdust-under-the-finger-nails timber frame system build specialists. But in Scotland, as a UKTFA press tour of timber frame sites demonstrated, they’ve clearly become the rule rather than the exception.

“What we’ve also seen in Scotland is the emergence of a generation of sub-contractors who are immersed in timber frame,” said Stewart Dalgarno, timber frame builder Stewart Milne’s director of product development and chairman of the UKTFA. “This has helped spread common practices and standards and, in turn, contributed to the industry’s development.”

One port of call on the UKTFA fact finding trip was Crystal Gait, a development being built  by timber frame supplier and erector Thomas Mitchell Homes, comprising detached private housing and a multi-storey private/affordable apartment block. The site was due an inspection for the NHBC pride in the job awards, so it was especially spick and span, but, taking that out of the equation, it still demonstrated the logic and method of timber frame construction being exploited to the full.

One key element of the approach is to stock pile as many materials  as possible in a pound on the site, so the inherent speed of erection of the building shell isn’t offset by a late delivery.

“For instance, we have the plasterboard delivered with the timber frame so we have a seamless process and can call it off as needed,” said Mitchell sales director Ken Rowan.  “The procurement process is key.”

“And it’s common practice for all materials not used that day to be collected and returned to central storage to further maximise efficiency” said Dalgarno.  “Tidiness is also crucial.”

Effective communication with the workforce is another factor in “optimising” the construction process. 

“On this site we have just three full time employees, the tele-lift and fork lift drivers and a site manager, and the rest are subbies,” said Rowan. “To make sure everyone knows their role and is up to speed on where we are on the development, we have a full meeting every month.”

“The combination of structured communication and the subbies’ understanding of timber frame also means that we can have a single manager overseeing several sites , saving costs and fostering a common approach” said Dalgarno.

The erection of the housing on the Mitchell site clearly followed a highly regimented approach. Neighbouring buildings were at different stage of construction, from concrete slab to stone and brick clad completion, like a timber frame evolutionary tree.  It’s an approach that means different site workers aren’t perpetually under each other’s feet.  

The houses went from foundation to wind and water tight inside a month and were expected to be ready for viewing in seven weeks.

“And in the future, with companies adopting  more pre-fabricated elements, we expect the process to become even faster,” said Dalgarno.  

The Crystal Gait apartment block also highlighted how Scottish builders have streamlined timber frame work practices. The first fix, or ‘roughing joiner’  handles the main frame erection and leaves each apartment open-plan for services to be installed.  The same joiners, rather than tackers, then put up the plasterboard and finally fix the partition walls ready for second fix.  This approach not only cuts the number of trades on site, it eliminates the need for numerous noggins and studs to link walls. In fact, Dalgarno estimates, it saves up to 40 studs per flat, with no compromise on rigidity, and reduces the number of processes involved in each join from between 30-40 to just 10.

“Keeping the apartment open plan initially also creates a more comfortable, safer working environment and allows you to use more whole sheets of plasterboard and insulation,” he said. 

The second site on the UKTFA tour was phase 3 of Edinburgh’s £50m Hyvots regeneration project, which is replacing 268 flats, in grim,1960s concrete high rises, with 342 new homes in timber frame bungalows and low to medium-rise apartment blocks.

The development, being built by Hart Builders with frame supplier Walker Timber, also follows the open plan construction approach and demonstrated the practice of stockpiling components on site, with shrink-wrapped pre-finished, pre-glazed wood windows and doors stacked and ready to install.

Like Mitchell, Hart was using lift trucks rather than cranes, as they’re cheaper, quicker and easier for workers to unload, with scaffolding initially surrounding just three sides of each building  so  internal components can be simply lifted in.

The development also highlighted the key role played by the scaffolding contractor on a multi-dwelling timber frame development.

“We generally have a scaffolder here the whole time, as the rate of build means erecting and dismantling the scaffold around the site is a constant process,” said site manager Mitch Drysdale.  

To boost efficiency further, he added, the “quick stage” scaffolding features ‘hop up’ platforms which can be lifted as the building shell rises .

Touring the site, Dalgarno also pointed out that all the joists supplied by Walker were solid timber – not an I-beam to be seen.

“Because the shell is weather-tight so quickly, there’s less risk they’ll be exposed to the rain,’ he said. “That means less likelihood of movement, which is usually the big I-beam selling point over solid wood – and generally good quality timber is cheaper than I-beams and can be easily serviced with a traditional plumbing and wiring approach.” 

Given the current construction slowdown, some in the brick and block community maintain that the high speed of timber frame construction is less relevant than when  demand was roaring ahead. Dalgarno takes the opposite view and says the Scottish timber frame experience proves his point.  

“It means you don’t have workers and equipment locked up on a site for months,” he said. “You can get the sale, go rapidly from foundation to completion and move on to another development. Timber frame delivers this value in Scotland – it won’t take long before more English developers wake up to these benefits too.”