Building physics

Fire in timber construction

Fire is considered a major risk for timber construction and many people therefore shy away from using wood as a building material. Yet timber constructions are safe buildings. More in this article.

Building physics in cross laminated timber - Fire protection

Fire is considered a major threat to timber construction and many people therefore shy away from using wood as a building material. However, this does not stop experts in building physics from emphasizing the advantages of solid wood as a building material. This is because, unlike other building materials, solid wood is very fire-resistant. In this blog post, we explain why timber buildings are safe buildings and how solid timber components such as CLT react in the event of a fire.

Unfounded fear.

Wood as a building material is very fascinating. It gives the building project a warm and natural appearance. However, there is always concern that timber buildings will collapse more quickly in the event of a fire than a conventional solid concrete structure. However, this fear is unfounded. Timber is safe and predictable in the event of fire. If one side of a solid wood panel burns at around 1,210 °C, only 9.5 °C will penetrate through a 10 cm thick wall to the other side in 60 minutes. There is a very simple reason for this: solid wood burns very slowly.

Its structure further increases the fire resistance of a wooden building. Before the wood burns down, the water it contains must evaporate. This requires huge amounts of energy. The high moisture content of wood (approx. 12%) delays the extinguishing process and thus achieves a longer fire protection period. At a burning depth of just a few millimeters, wood can no longer be used as a load-bearing element, but there are other factors that keep the main module beam stable in the event of a fire.

Solid wood protects itself in the event of fire through special reactions. Burning on the surface slows down the penetration of heat deep into the wood and creates a protective layer. This also slows down the spread of the flames. Fire-fighting measures for wooden components are therefore easy to design, as the extent of the fire can be predicted and optimally calculated.

Stable & predictable.

CLT is a building material that consists of several layers of cross or longitudinal veneers. There are three classifications of fire protection in this area. The frequently used stabilizing fire protection treatment is used as standard in CLT production. In order to ensure safe fire protection when using this construction material, only two measures need to be observed. Only small cross-section thicknesses are permitted and a protective coating must be applied to the surface to reduce the effects of fire.

Anyone involved in the construction or renovation of a building should not be influenced by unfulfilled preconceptions about timber constructions. In contrast to other building materials, wood reacts predictably and stably in the event of a fire, as long as the prescribed fire protection measures are adhered to and appropriate components are used. Solid wood, especially CLT, is therefore a forward-looking building material that will become even more important in the future.

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