Deborah Ritchie spoke to Andrew Carpenter and Dominic Lion about innovation in engineered timber and the potential benefits for the construction supply chain


Whilst the Grenfell disaster was not caused by timber, the issue of fire risk in construction is, and probably directly as a result of Grenfell, rarely out of the news. Is timber safe?

Andrew Carpenter: As you quite rightly say, Grenfell was not a timber related fire, however, we are absolutely behind the government’s drive to improve the quality, compliance, and health and safety agenda. In fact, it’s a path the Structural Timber Association has been on as a trade association for more than 10 years. It was in 2011 that we issued some fire safety guidance, our 16 steps to fire safety, and they’ve been accepted as best practice throughout the sector. Now structural timber, like many other building materials, will burn. The whole essence of this is to make sure that we get the design, the manufacture, and the erect and installation process correct. With that in mind we have an STA Assure programme. All our members are required to adhere to it. They are audited on it and therefore assuming that it is designed properly, manufactured correctly, and then erected correctly, then structural timber has no more risk than any other building material. It’s predominately used in housing, that’s where it’s most well-known, low rise housing in particular. In Scotland, three in four homes are built in timber. So we are unusual here in England and Wales in that it’s the opposite. But then more and more now we are seeing other areas where timber could and should be used, one of which is dealing with the challenge of achieving net zero by 2050. So we are seeing it used a lot in student accommodation, in hotels, in care homes, in schools now and so on.

What moves are being made in the increased use of timber in construction at the moment, which market segments are using engineered timber systems already?

Dominic Lion: We are seeing a significant increase in enquiries in the last nine to 12 months and for office developments in particular. Whilst the government is still undertaking its review into how high one can build in combustible materials there is perhaps a fear of starting something that might ultimately be in breach of future regulations. So there is a reluctance to start building or designing in any structures that are too tall and particularly in the residential sector where we think the guidance is going to be changing. But in the commercial sector I think the large owner developer clients out there are looking at almost all of their schemes with a timber tint to their lens now. So they’re certainly asking the question of their design and engineering teams almost across all schemes.

There is a sustainability message here isn’t there - from the environmental risks perspective through to ESG in investment. Wood, it is argued, can be part of a circular economy approach to construction as the use of other materials is more costly in terms of energy use.

DL: Absolutely, and I think that’s the largest driver behind the uptick in enquiries we are seeing and the uptick in appetite that we are seeing across the sector. Major corporate businesses are setting out their next 10-year plans and goals, and are talking to investors about what is important to them over this period. There is a universal understanding that we need to start doing something significant about our environmental impact pretty quickly, otherwise we are going to be – or we are already depending on who you talk to - in the middle of a climate crisis and it’s slowly getting worse. We need to put that E of ESG right at the top of the agenda in a way that we have not previously, and you can see that very tangibly filtering through big businesses. Essentially, I think there are now businesses out there who are almost being told, ‘we will only continue to fund you and invest in you if you hit very stringent criteria around carbon neutrality and sustainability’.

AC: We are now also seeing the big housebuilders take a real interest in the timber frame sector.

What are the demonstrable climate benefits and what’s the time frame against those? How can timber construction play a part in getting us to net zero by 2050, what does that look like, what’s the road map for that?

AC: We all know trees absorb carbon dioxide as they grow, then when the tree is harvested the carbon remains stored in the timber until the end of its physical life. Now roughly one tonne per metre cubed. While the carbon is safely stored in the timber product, such as walls and doors, more trees are planted absorbing and storing carbon as they grow. So every time we cut down a tree it’s reckoned that we plant another five. So if we take the housing market, now it’s widely thought that we need 300,000 homes a year here in the UK. If we were to build those in timber frame, we would actually have six million tonnes of carbon stored. That’s why it’s so important that we do consider timber frame as the main building process for house building.

One of the barriers to growth you say is resistance from insurers to cover timber in construction. What is it that they object to?

DL: Unfortunately, they object fundamentally to the experience they’ve had to date of timber in construction, which is unfortunately fairly limited. The property and construction markets are global industries now, so insurers are covering products and buildings all over the world. The banner of timber is a very widely cast banner and essentially anything that encompasses wood gets put under the banner of timber when it’s insured through London. Now I think the UK insurance market in particular has suffered perhaps unduly from an experience of insuring timber developments elsewhere in the world, where perhaps construction methodology and risk management isn’t as highly regarded as it is in the UK. Invariably, more of those projects and developments have gone up in flames. That is a huge issue, and one that needs to be addressed by having a conversation about standards. The second issue is a lack of understanding and I think the insurance industry is an industry that is run in essence by actuaries who base their underwriting criteria on reams of data. I think there insufficient data to get insurers to a place where they feel entirely comfortable with timber today. The unknown brings about a perception of increased risk. If managed in the right way, timber is actually no more of a risk than any other building material. There have been huge changes in the development of engineered timber. One example, I think, is the perception that’s when a timber framed building catches fire it is effectively going to burn in its entirety, and therefore as an insurer they have to factor in the potential 100 per cent loss of that building as a realistic expectation of what would happen if a fire started on that asset.

Typically in comparison with a steel or concrete building they might be looking at a maximum loss of anywhere from 30 per cent to 50 per cent of that building in the event of fire. Because there is an expectation that it would be able to be extinguished and they would be able to salvage, recover a good chunk of that building. Whereas there is perhaps the perception with timber that once the fire starts it is going to burn in its entirety and they will have to pay out for a complete reinstatement of that building. Actually replacing, reinstating a timber asset shouldn’t be any more difficult than a steel or concrete equivalent. So that is an education piece that we as an industry need to deliver to insurers to change perceptions and understanding. Because historically with traditional timber there have been significant numbers of total losses as a result of fire and we need to explain that that’s not how things are being done going forward. I am also not so sure insurers have fully taken account of the benefits of using timber, when it comes to how long that timber is on the sites at its most exposed state, and most susceptible therefore to fire or water ingress because so much more can be done off site with timber. The actual timber once on site can be erected so much more quickly. The amount of time that you have that timber at its most exposed stage is significantly reduced I would suggest compared with concrete or steel.

AC: We have witnessed quite a sea change in the insurance industry in the last couple of years, in that they are wanting information, they are wanting knowledge, they’re wanting to be educated in the use of structural timber systems. I think there’s a realisation by them that this is going to be a growing market; more and more structural timber systems are going to be specified and used in the UK construction industry. So if they don’t understand the market they’re going to miss out. We’ve witnessed real progress in the last couple of years. In fact, recently we had meetings with the Association of British Insurers and the Fire Protection Association, and we have agreed to work collaboratively. So wherever the issues are we want to understand them and together we’ll find solutions. For me, that has to be seen as a way forward as we collectively try to overcome the climate crisis.



This article was published in the November-December 2020 issue of CIR Magazine.

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