Can mass timber construction usher in a green revolution?

A highlight of January’s Property Week climate crisis summit was listening to Andrew Waugh, founding director of Waugh Thistleton Architects, extol the virtues of mass timber construction while assuaging the myriad concerns of his audience with the assuredness of a man who has succeeded where others have feared to venture.

There is excitement within the industry about the decarbonising potential of mass timber (MT) and it is encouraging to see the number of MT projects now coming through planning. There are, however, still misconceptions that continue to impede its widespread adoption.

Obtaining construction and property insurance for MT buildings is more difficult than for steel and concrete, but not impossible. The issue is that there are still comparatively few MT buildings in the UK, and almost none that have been the subject of an event resulting in a significant loss claim.

This means insurers do not have the volume of loss history to accurately assess the risk factors and evaluate claims performance in this area. However, as more MT projects are completed, more information will become available and there will be an increasing number of insured projects that can serve as examples.

In the meantime, construction and property insurance is available for MT buildings, provided insurers are engaged early in the design process and given the opportunity to understand, and influence the management of, key risk factors. To that end, the Alliance for Sustainable Building Products is preparing to launch the Mass Timber Insurance Playbook, which will provide a step-by-step guide.

Building at scale

The post-Grenfell regulatory environment has stymied the use of MT on high-rise residential accommodation. However, regulations in this area will hopefully become more nuanced as more is understood about the fire performance of MT buildings.

Preconceived notions about the limitations of MT when building at scale or at height are also being challenged. The Black & White Building (pictured), London’s tallest MT office building, stands at just shy of 18m high. Waugh Thistleton’s Dalston Works, which was the world’s largest cross-laminated timber building on completion, stands at 33m. Even taller examples exist in North America and Scandinavia, with Mjøstårnet in Norway standing at 85m high.

MT construction also lends itself well to retrofit and refurbishment projects. Its lightweight prefabricated nature translates to smaller loadings, which makes it well suited to vertical extension and massing projects. MT products can be more expensive per unit than their more traditional counterparts, but they have the potential to deliver net cost savings.

The prefabricated nature of the products translates to a shorter onsite construction phase, with a corresponding reduction in labour and prelims cost; MT structures tend to be lighter and, therefore, require smaller (and less expensive) foundations; and interior finishes and ceilings are often omitted as clients and designers plump for a raw wood aesthetic.

Forestry for MT is located mainly in Europe, so currency exchange is a consideration, but the same is true of many building products. A significant proportion of the cost of MT is in the timber itself (around 50% to 70%), so clients need to be prepared to spend quicker and may be required to make advance payments to secure orders.

Demand in the UK is at a fraction of total European capacity and timber is a completely renewable material, so continuity of supply is also not a concern. The clock is ticking and, in the words of American journalist Edward R. Murrow: “Difficulty is the excuse history never accepts.”

Adriano Amorese is a partner in the construction group at law firm Mishcon de Reya