Auto-extinction of engineered timber: the application of firepoint theory

Alastair Bartlett, Rory Hadden, Luke Bisby, Barbara Lane

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Engineered timber products such as cross-laminated timber (CLT) are gaining popularity with designers due to attractive aesthetic, sustainability, and constructability credentials. The fire behaviour of such materials is a key factor preventing the widespread uptake of buildings formed predominantly of exposed, structural timber elements. Whilst guidance exists to determine the residual structural capacity of timber elements exposed to the ‘standard fire’, the predominant approach to solving the issue of increased fuel load is to fully encapsulate the timber elements, stifling architects’ aspirations of exposed timber elements.
In this paper, the concept of auto-extinction – a phenomenon by which a timber sample will cease flaming when the net heat flux to the sample drops below a critical value – is explored experimentally and related to firepoint theory. A series of approximately 100 tests using the Fire Propagation Apparatus have been carried out to quantify the conditions under which flaming extinction occurs. Critical mass loss rate at extinction is shown to vary linearly with oxygen concentration from 3.5g/m2s±0.3g/m2s at 21% oxygen to 4.1g/m2s at 16%. External heat flux and airflow were not found to affect the critical mass loss rate within the ranges tested. Applying the firepoint equation to the experimentally obtained values demonstrates a good correlation to within 0.2kW/m2. The analysis demonstrates that if the input parameters can be calculated sufficiently, then firepoint theory may be used to predict whether auto- extinction will occur. With further testing and refinement, this method may be applied in design, enabling architects’ visions of exposed, structural timber to be realised.
Original languageEnglish
Title of host publication14th International Conference and Exhibition on Fire Science and Engineering (Interflam 2016)
Publication statusPublished - Jul 2016


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