Fire protection in timber construction

CLTPLUS a safe building material

Wood is a powerful building material: its specific strength properties rival those of reinforced concrete, wood processing is very versatile, wood has a positive effect on interior climates and well-being and is significantly more sustainable than other building materials. In recent decades, wood materials such as cross-laminated timber have been developed through further processing steps, making the building material even more efficient and more predictable in terms of building physics. This provides a firm basis for using wood in multi-storey timber construction as well as reason to discuss the topic of fire protection in timber construction. As everyone knows, wood is a combustible material, but the char layer that forms leads to a predictable burn rate. The load-bearing behaviour of wood can therefore also be calculated mathematically, including under the influence of fire. In contrast to steel and reinforced concrete structures, wooden structures remain stable even at very high temperatures. The fire resistance of the entire structure must be considered when evaluating individual elements such as walls or floor ceilings. All details can be found here and in the document below. 

1.    Is CLTPLUS a safe building material?

At least three layers of cross-glued single-layer panels make CLTPLUS an almost universally applicable, exceptionally load-bearing wooden construction product. Wall, ceiling or roof elements are created from large-format CLT solid wood panels. The high level of prefabrication enables short construction times without drying phases. CLTPLUS is a stable and safe building material that is individually and precisely prefabricated to size in the factory. The high degree of prefabrication also makes it economical and at the same time stable, natural high-tech building material that excels thanks to its great ecological balance and CO2 storage capacity. 

Wooden buildings are still not given enough credit in terms of fire resistance. Ensuring stability in the event of a fire is not just a question of material, but also of quality planning and execution. The moisture content of CLTPLUS of around 12% means that water must first evaporate before the wood begins to burn. This results in a charred surface, but not a loss of static properties. CLTPLUS is a stable and safe building material with predictable fire behaviour tested for fire resistance by Holzforschung Austria and TU Munich.

2. How does CLTPLUS behave in the event of a fire?

If CLTPLUS is exposed to fire, the stored water molecules begin to evaporate at around 100 °C. At temperatures of 200 to 300 °C, the long-chain molecules in the cell walls are broken down and come to the surface of the wood in gas form, where they react with the oxygen contained in the air and burn.


THEURL subjects all CLTPLUS elements to a fire test to prove their fire resistance. THEURL's CLTPLUS elements are classified as D-s2, d0 according to EN 13501-1. The fire class corresponds, among other thing to fire protection panels or fire protection glass and is characterised by limited flame spread, low smoke development and no formation of flammable droplets.

3.    What are tested and approved components?

The online catalogue includes approved wood materials and component structures that have been tested in terms of building physics and ecology. The characteristic values can be used as a basis for providing evidence to building authorities.

All details can be found here in the document.

4.    What solutions are available for the partitioning variants?

Officially tested and innovative solutions in cross-laminated timber are possible without complex fire protection cladding in open reveals. Irrespective of whether as a combination bulkhead or individual implementation.

Examples can be found here in the document.


Our team will be happy to answer any further questions you may have.

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