Posted on 04/11/2019
New fire safety challenges for wood products

Presentations noted the strong growth potential of wood-based materials, as a sustainable and ‘desirable’ construction material, but also the specific fire safety challenges to address.

Colleen Wade, Branz Ltd, New Zealand, noted that wood structure construction is in demand, because of sustainability objectives, but also because of lower costs resulting from rapid, off-site modular construction and lower weight (lower foundation costs). Her paper (Interflam conference paper prize) presented development of a fire model for mass timber construction, including kinetic wood pyrolysis modelling, compared with five enclosure fire tests (4.5 x 2.4 x 2.7 m) with CLT (cross laminated timber) panels and glulam structural elements. In these experiments, gas temperatures in the enclosure reached over 1000°C around 20 minutes after ignition by wooden cribs.

Fire safety questions are posed concerning fire behaviour of CLT (cross laminated timber, see below) and risk of continuing pyrolysis and delamination during the decay phase of the fire.

Marc Janssens, SwRI (Southwest Research Institute), USA, discussed the development of a room fire test method used to identify CLT adhesives that can degrade at a relatively low temperature resulting in delamination, fire re-growth and a second flashover during the decay phase of the fire.

Fire behaviour studies of wooden construction products and CLTs were further discussed by Robert McNamee, Lund University, Sweden. Jean-Christophe Mindefula, Bordeaux University, France. Bernard Girardin, Efectis, France, discussed engineering methods for fire contribution of wood (ISO 9705). Katrin Nele Mager, Tallinn University of Technology, summarised design for fire resistance of timber-based joists. Christian Gonzalez Crespo, Carleton University, Canada, discussed the fire performance of concealed steel moment-resisting mass timber connections.