Fire Safety in Timber Construction

The nature of combustible load-bearing structures

Multi-storey timber construction, particularly using cross-laminated timber, has grown strongly in importance in recent years. Unlike steel, which loses load-bearing capacity abruptly in a fire, timber chars at the surface at a largely predictable rate while the core beneath retains its capacity – behaviour that can be translated into a fire resistance duration using recognised design methods.

Measures

Key measures include calculating residual cross-sections against the required fire resistance duration, encapsulating combustible elements with non-combustible linings in particularly sensitive areas, careful detailing of fasteners, which act as thermal weak points, and complementary extinguishing technology such as sprinklers in corridors and concealed spaces. Workmanship and joint detailing have an above-average influence on actual fire behaviour.

Insurance relevance

Because loss experience from major fires in modern multi-storey timber buildings remains limited, risk engineers scrutinise design calculations, the encapsulation concept and complementary extinguishing technology particularly closely for such properties. Missing verification or deviations from approved designs lead to conditions or sublimits more often than in mineral-based construction.