The Structural Timber Association Special Interest Group has been formed to address challenges in the sector, through a series of work packages to provide both guidance and evidence to support the fire safe design of mass timber High Rise Residential Buildings (HRRB) and commercial buildings.

Cross Laminated Timer (CLT) is increasingly adopted as a structural framing solution due to its sustainability benefits and impact on reducing construction programme. CLT is formed of a series of timber lamellae arranged orthogonally to give improved homogenous stiffness and stability. As an engineered timber product in residential applications, it is common to have all apartment and/or room bounding surfaces formed as CLT, i.e. the CLT not only forms elements of structure, but also serves a separating function.

In most instances in residential applications, the CLT is lined in some manner, plasterboard for example. For commercial projects, the scale of the fire enclosure is much larger, with the CLT generally only forming an exposed ceiling / slab structure.

For HRRB and similar types of purpose groups, the Building (Amendment) Regulations 2018 set out new statutory requirements in respect of the materials forming external walls and specified attachments which have been taken into account with this research.

The programme of fire performance experiments has been undertaken by leading CLT manufacturers including Binderholz, B&K Structures, Eurban, Henkel, KLH, OFR and Stora Enso, to provide test based evidence of behaviour which will enable specifiers and the market in general use CLT in the knowledge it is a safe building material.

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