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The rise of offsite timber construction

by Liam Turner

Andrew Carpenter, chief executive of the Structural Timber Association (STA), talks to Build in Digital’s Michelle Gordon about the growth of offsite timber construction and the STA’s role in giving the sector an authoritative and united voice

Mark Farmer’s Modernise or Die report in 2016 was undoubtedly a catalyst for the uptake of offsite construction methods with the sector having grown significantly in recent years but there is still some way to go before offsite solutions work their way into the mainstream.

The Structural Timber Association was formed eight years ago, a coming together of the UK Timber Frame Association and UK SIPs Association. Its mission is to enhance quality and drive product innovation through technical guidance and research. Its membership has grown from around 200 organisations in those early days to over 800 today – an indication of the interest in structural timber as a building material, says its chief executive Andrew Carpenter.

“Certainly, when we kicked off eight years ago, one of the main obstacles was whether people wanted to use offsite solutions and you had to work hard to get people to accept MMC as a bonafide solution to building,” he adds.

“I think that’s been overcome now because everywhere you go, there’s a direction of travel where MMC is preferred.”

Timber frame buildings are constructed in a factory environment using precision engineering, making it much quicker than traditional construction. But speed of build is not the only advantage, the factory environment means better quality and fewer defects due to dry, consistent conditions which enable better quality control, as well as a safer more pleasant environment for workers.

There are also fewer people and less noise on site as most of the work is done in the factory, including in some cases the installation of doors, windows and insulation.

Climate change

Timber is also a carbon negative building material, storing carbon dioxide from the atmosphere and there has been increased interest in its environmental credentials as we all become more aware of our carbon footprints and the challenges posed by climate change.

“Everyone now is turning to timber as a low- or zero-carbon building material and trying, where possible, to substitute it where they would have used concrete or steel which produces high levels of CO2 emissions,” says Carpenter.

“So, we find ourselves now eight years on in a situation where MMC is an accepted direction of travel in terms of building method, and timber is the building material of choice.

“I think that’s probably an indication of why we’re doing so well membership wise, and certainly our market share is growing year on year, which supports that.”

As well as driving the growth in structural timber’s market share, the STA is focused on raising standards through STA Assure (its quality assurance programme) and establishing itself as a trusted source of guidance and information.

Timber’s safety credentials

It is also working to tackle misinformation and a lack of understanding around timber’s safety credentials, an ongoing area of focus as the Building Safety Bill starts its journey to Royal Assent.

“One of our jobs is to protect our sector from any negative influences,” explains Carpenter. “What we have to do is put forward test evidence and documentation that can show that when it is used, designed, and constructed properly, timber is as safe as any building material.

“We find ourselves in a situation where MMC is an accepted direction of travel in terms of building method – and timber is the building material of choice”

“This was highlighted in a conference that I attended with Dame Judith Hackitt.”

The vast majority of timber frame buildings (closed panel frames and SIPs) are houses, with Cross Laminated Timber (CLT) tending to be the preferred option for commercial buildings, as it is suitable for taller structures, but interest in all types of structural timber is increasing across the board.

Modernise or Die

“Emma-Jane Houghton, responsible for procurement in the New Hospital Programme, reports that they’re requiring 71% of the build to be MMC, so, that gives you a flavour of how things have turned round,” says Carpenter.

“Basically, Mark Farmer and his review, Modernise or Die, has been the catalyst for that massive change in culture, where people are now actually trying to go down the MMC route as a main priority.

“I think what the report has done is remove the stigma of MMC as a building solution, and so you’ve now got government departments and councils and so on, who are suggesting that you should consider MMC as a priority.”

While Farmer’s review has been the biggest catalyst for the adoption of MMC, the skills shortage, which has been exacerbated by Brexit and the loss of European labour, has also been a driver, and the pandemic has accelerated the change.

“If you look at Boris’s Build, Build, Build mantra, build back faster is MMC, build back greener is net zero, and build back better is the quality agenda, the Hackitt Review, and they all fall into timber frame construction,” says Carpenter. “It’s quicker, faster, it’s greener and with STA Assure, it’s better.

“So, we’re right under the microscope at the moment and it’s a great place to be.”


But while the use of offsite construction is clearly on the increase, there is still work to be done in terms of education if it is to become a truly mainstream building method across the UK.

“Initially, when we kicked off eight years ago, the first job you had to do was persuade people that MMC, offsite solutions, was a bonafide solution,” says Carpenter.

“Nowadays, you don’t have to do that, but we still have a long way to go in terms of training.

“In Scotland, three out of four homes are built in timber frame, so there’s no problem north of the border, but in England, it’s more like one in five, so the bulk of the industry is still used to working in masonry.”

“The biggest unique selling point we have [for MMC] is the net-zero agenda, and that’s not going anywhere”

Carpenter continues: “We need a big awareness or education project because it is still relatively new for many people.

“We need to be able to educate architects in the design of timber frames, because at the moment a lot of our members are taking architectural designs and having to change them internally. The same with engineers and surveyors.

“But the biggest obstacle has been overcome in that is it is now accepted, so there’s a desire to gain that knowledge and the insurance and mortgage industries are clamouring for information from us because they understand it’s no longer a sector they can ignore.”

Market share

Looking forward, Carpenter expects structural timber’s market share to grow significantly, with timber’s environmental credentials continuing to be a huge driver.

“It wouldn’t surprise us in the next year or two if we’re up to about 33%, so, one in three homes, because that’s the direction of travel that the house building community and developers seem to be to be moving in,” he says.

“I can only see MMC generally increasing particularly in housing because the need to build these 300,000 homes a year hasn’t gone away.

“And of course, the biggest unique selling point we have is the net-zero agenda, and that’s not going anywhere.”

The construction sector is currently responsible for 40% of emissions, with cement accounting for 8% of those emissions, and The Climate Change Committee has suggested increasing the use of timber in a bid to bring the industry’s emissions down.

“The opportunities for structural timber are fantastic,” says Carpenter. “I’m in a great place. I’m loving what I’m doing, personally, for the organisation, and also for the sector.

“And what we’re doing in business is good for business but it’s also good for the planet, which from a legacy point of view is brilliant.”

Main image: Andrew Carpenter, chief executive of the Structural Timber Association

Read next: Mark Farmer: The state of MMC in 2021

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