CLT stands up to site fires, says report

1 May 2014

Cross-laminated timber (CLT) structures can still retain their integrity even in construction site fires because of the material’s limited charring rate, a report commissioned by Finnish wood and paper producer Stora Enso Building & Living suggests.

A large wooden structure’s ability to meet fire protection requirements once it is complete has already been widely acknowledged within the industry. But how fireproof such structures are if a fire breaks out or is started when they are still being built has until now remained a matter of debate.

Stora Enso wanted to show that CLT, at least, can withstand construction fires as well as any other construction material, providing enough time for site workers to escape to safety.

So it has commissioned an assessment from UK- and Finland-based fire safety design consultancy Markku Kauriala which uses a fire dynamic simulator that was developed by the National Institute of Standards and Technology in the USA and Finland’s VTT Technical Research Centre along with several other international universities and companies.

The report, which has not yet been fully released, is backed up by over 80 separate scientific references to other studies.

Wayne Probert, UK sales manager for Stora Enso Building Solutions, said: “We decided to invest in this report in order to help specifiers understand the inherent properties that make CLT such a unique and valuable material for future construction developments. Simulation enables us to model the entire buildings in full scale and to evaluate multiple fire scenarios. We believe this research will prove invaluable to anyone wishing to build in CLT.”

Mika Kallio, senior vice president at Stora Enso Building and Living, added: “The report provides scientific evidence underlining the significant difference under fire between traditional timber construction methods and massive wood such as CLT, especially during the construction process. The study also provides detailed technical information concerning fire safety of wooden multi-story buildings in general.”