It’s often touted as an ideal sustainable building material, but England still lags behind when it comes to using timber to build new homes. Could this soon change? Tim Clark reports
Among the many avenues that are explored to solve the UK’s housing crisis, timber-framed construction is raised perennially as one option to solve the shortage of new homes, and also save carbon.
However when it comes to house building the industry has, at least thus far, failed to truly take on timber as a mainstream construction technique. In 2019 fewer than one in 10 homes built in England were timber framed.
By contrast, over 90% of new homes in Scotland used the technique.
Across the UK, of the 190,612 homes built, 40,053 were timber framed, with 22,790 of those situated in Scotland, 13,711 in England, 2,183 in Northern Ireland and 1,369 in Wales.
Figures from the National House Building Council (NHBC) suggest that timber frame market share has developed from 19% in 2015 to 22% in 2021. The report did state that it may be possible to see timber use across the UK grow to around 27% by 2025.
Can the use of timber really take off?
One housebuilder that is looking to change the Venn diagram of housebuilding and timber use are Greencore Homes. Founded in 2013 and backed by finance giant M&G, the housebuilder aims to build up to 10,000 carbon-positive homes over the coming years. Timber frame is a key plank of the company’s plans to reduce carbon emissions.
“The timber roadmap is part of thinking about how the process of reducing embodied carbon works,” says Jon Di-Stefano, chief executive of Greencore Homes. “Because if developers keep using bricks and blocks, there’s only so much you can do to reduce your embodied carbon.
“Timber, when it is being grown, locks up carbon rather than emitting it, therefore from an embodied carbon perspective no matter how you measure it you are immediately in a better position from an environmental perspective.
“The government is looking at how timber can be part of the future homes standard.”
Due to be published in 2025, the new future homes standard aims to include details of how developers and housing associations can meet net zero commitments, as well as incorporate higher quality specifications to their homes.
Late last year, the government also weighed in on the issue, launching a new timber roadmap to help increase the amount of timber used in the construction sector in the UK.
In a policy paper the government stated that through the Timber in Construction Roadmap, it will increase the safe use of timber in construction (TiC) in England, look to reduce the amount of embodied carbon in the built environment, and also help spur a drive for increased tree planting across the country.
The plan promises to create new jobs, raise the UK’s capacity for forested timber, and provide new habitats for animals.
“It will innovate the economy, play a role in creating green jobs and also help meet our tree-planting targets,” said forestry minister Rebecca Pow, noting that the proposals meet a key part of the government’s net zero strategy. “Investing in timber is investing in growth and levelling up. The built environment is responsible for a huge proportion of UK carbon emissions, and using home-grown timber in construction is key to reducing emissions.”
As a fairly densely populated island nation, Britain isn’t always considered an option for large-scale timber or forestry, however the roadmap aims to increase forest cover to 16.5% of the UK as a whole.
“At the moment we have to import most of our timber from Europe, because not much homegrown timber is FSC approved, which means you can’t prove that it has been replaced by another tree,” Di-Stefano adds.
“The smallest element in the carbon footprint of most things is the transporting of the material, so the difference from using bricks and blocks on a housing site vs timber from the Baltic can be 95% [of carbon emissions].
“The biggest challenge we have in the UK, apart from the FSC accreditation, is the strength of the timber. The UK timber industry doesn’t tend to cater for structural timber quite as much [as it needs to].”
Structural transformation
A lack of structural timber is an issue, especially for larger projects. A new project which is being spearheaded by Edinburgh’s Napier University and the Centre for Offsite Construction & Innovative Structures (COCIS) is looking to change this.
Titled Transforming Timber, the initiative will manufacture the first Scottish-sourced cross-laminated timber (CLT) and nail-laminated timber (NLT) housing unit – including wall, roof, and floor – using the UK’s only vacuum press at CSIC’s 35,000 sq. ft. innovation factory in Hamilton.
According to Transforming Timber, the project could ultimately lead to the mainstream use of home-grown timber in Scotland and the rest of the UK construction, as well as the development of the country’s first engineered timber manufacturing plant.
Another key issue for timber frame construction has been fire safety.
“On blocks of flats, timber frame is one of the factors that would increase risks. So we were more nervous about timber framing than we would have been pre-Grenfell,” says Paul Hackett, chief executive of Southern Housing Group.
Hackett describes how the timber issue is one of a number of safety concerns that housing providers have to consider when looking to build new schemes.
“Our primary concern is about getting the best possible schemes and the best value for money, so that’s the starting point. Whether it [a particular scheme] is in timber frame or not, timber itself is just one of the potential risk factors in achieving the goals we’re seeking to achieve, alongside affordability and others,” he adds.
“So if timber frame was going to play a bigger role, we’d have to have assurance across a whole range of different areas. Including manufacturers specification, fire safety, workmanship, that we need to be clear about because so many things can go wrong, and so many things that can look okay, when a building is specified but ends up being something else when it’s built.”
A report into a fire at a block of flats in Barking in 2018 concluded that timber balconies posed a “significant hazard”, even though it concluded that the overall building was safe.
The fire is suspected to have been caused by a barbecue being used on one of the balconies, which have subsequently been banned on the scheme.
Another fire at a block of flats owned by Metropolitan Thames Valley Homes at Worcester Park in Sutton saw 23 flats burn down.
Material safety
Politicians have raised questions over fire safety, with some calling for sprinklers to be fitted to buildings housing the elderly or young children to help contain fire spread.
Di-Stefano says that the safety regime has changed in the UK post-Grenfell. “You can do fire tests on the makeup of your house that [to show that the house is] well within the minimum standards for making sure people have got plenty of time to get out, should fire take hold and not be able to stop it,” he says.
“In technical terms, when you’re mainly talking about two story houses, you don’t need the same level of fire safety as you do for six or 10 storeys.”
According to Di-Stefano, developers who are building post-Grenfell schemes of that size will still, even with the increased safety measures bought in via the Building Safety Act, see a higher realistic risk profile from fire than a normal semi-detached timber framed home.
He does recognise, however, that whenever anything “new” is tried, then the market, and in particular insurers can need some convincing.
The key issue for Hackett and other housing association chief execs is assurance – the knowledge that what has been built, is safe.
The Grenfell fire in June 2017 has led to an overhaul of the entire industry in a quest to ensure the tragedy is never repeated.
This has involved among others the report by Dame Judith Hackett on building safety, as well as the Grenfell Inquiry, and the introduction of the Building Safety Act (BSA) in 2022.
Any material is only as safe as the construction regime that oversees it. Concrete may not burn, but major structural issues with RAAC show that if not installed or maintained properly – or if used beyond its expected lifespan – it can become a potential danger.
The disconnect between what is designed and what is built was a key focus in the post-Grenfell era, and the BSA should in theory address one of Hackett’s key concerns.
From April new rules mean that almost any building – not just high risk buildings (known as HRs) need to have a clear chain – will need to have a principal contractor and principal designer, who will both be legally liable, including risk of criminal conviction, for any defects in construction work.
Those new rules, which come with a significant legislative punch, should see the quality of construction rise as the impacts feed through the system.
The allure of timber, especially as a low-carbon alternative to solve the UK’s housing needs, remains enough to tempt the government into action, the coming few years will see whether the market is similarly enticed to allow timber frame to truly take off.
Image credit: Foryoui3/Shutterstock
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