Advancing Timber: A Job Half Done

Having recently won its third successive Structural Timber Award for Commercial Building of the Year, along with the Pioneer of the Year award, Andy Heyne, Director of Heyne Tillett Steel, reflects on the industries collective progress to minimising our impact on climate change.

I’ll begin this with a bold assumption – everybody reading this already knows that the best way the construction industry can minimise its impact on climate change is through increasing the use of structural timber. But is progress on track? Over the last 4-5 years designers have kept their end of the bargain, filling the knowledge gaps and in the process developing innovative solutions to various technical challenges.

For example, we have a much greater and more respectful understanding of fire behaviour in mass timber buildings, generated in part through several largescale tests, although these are typically carried out independently by clients who are protective of their intellectual property rights and sadly almost never shared for the collective good. We now understand that the guidance within Approved Document B of the Building Regulations is too simplistic and not applicable to these complex structures.

And we also have a new breed of specialist structural fire engineers who have emerged to help us design safer buildings that are optimised through a more forensic approach. As structural engineers we have taken the mantle of timber champions, stretching beyond our core discipline to nurture an enhanced appreciation of other specialisms. More than any other, engineered timber buildings require a holistic approach, and with our increased knowledge and portfolio of completed projects, we now understand what works best in terms of aesthetics, acoustics and servicing strategy. As a result, we have pre-prepared responses to most challenges, allowing us to quickly squash any unfounded negativity or risk aversion before it can gain traction.

So why do I feel we have a such a long way to go and what can we do about it? One of the biggest logjams right now is insurance. Because decent historic claims-data relating to engineered timber buildings doesn’t exist, insurers err on the side of caution and increase premiums excessively, or more worryingly even regularly refuse to offer any cover. Certainly, the construction industry could do more to demonstrate the additional level of design and construction scrutiny that goes into a timber structure, which means in many respects these buildings are less risky, but when we do the prevailing response is frustratingly still negative.

Then there is the lack of fire test data in the public domain that specifically relates to cross-laminated timber, whether in support of auto-extinction analysis, or perhaps to provide certification of various products, such as fire rated walls or service penetrations. Surely it is in all our interests and transcends competitive rivalries.

A recent UN report suggests current net zero pledges will fail to limit global temperature rises to 1.5C this century. And based on my experience at present, I’m not sure we will even hit these targets without more affirmative action including:
• Make carbon targets mandatory on new development and shift the emphasis from operational to embodied carbon
• Invest in large-scale fire testing, to build confidence in timber as a primary structural material and provide evidence to justify removal of the blanket ban on combustibles in taller residential buildings
• If insurers continue to maintain their reluctance, Government must intervene to make insurance accessible.

If the Government is serious about achieving their zero carbon targets, they need to review the evidence on structural timber and make decisions based on facts, not misconceptions or politicking – and today, not tomorrow!