World-class in fire safety

The perception that ‘wooden buildings burn easily and quickly’ is widespread, but it is not necessarily true. Fire consultant Leif Tore Isaksen provides insights on preventing high-rise buildings from catching fire.

Wood will never become self-extinguishing, and not all types of buildings can be constructed solely with wood. Despite this, wood has certain properties that make it well-suited as a building material, even in larger structures.

“Wood has a controlled charring, and we can easily calculate how long a construction will withstand a fire. Additionally, in the event of fire damage, it is visible on a timber structure, whereas a steel and concrete structure may suddenly collapse. In that sense, wood can be considered more predictable in certain contexts”, says Leif Tore.

Leif Tore is a fire consultant at Sweco and was the project manager for Mjøstårnet – the world’s tallest wooden building, which not only opened doors in Norway but also caught the attention of the global timber construction industry.

Sweco has developed world-leading expertise in the design of timber structures and has also developed methods to demonstrate compliance with fire safety regulations in Norway.

Designing larger timber buildings is complex. Regulations require the structural system to be dimensioned to withstand a complete fire sequence, which necessitates a conservative approach and stringent fire safety requirements during the design phase.

“When constructing Mjøstårnet, we developed new methods for calculating fire progression and charring. This formed the basis for determining the necessary protection of combustible structures. The calculations are based on tests conducted at SINTEF’s fire laboratory and consider factors such as the cooling phase and the increased fire energy associated with the use of combustible construction materials”, says Leif Tore.

The work methods developed for Mjøstårnet have been further refined and improved through the design of various timber buildings, contributing to the advancement of expertise in this field.

“Building with wood is not a new concept in Norway – stave churches have stood for thousands of years, and traditional shipbuilding demonstrates how strong timber structures can be. The Building Act’s requirement for masonry construction has led to a loss of historical expertise in timber construction that we now need to recover”, says Leif Tore.

At Sweco, we are actively enhancing our expertise in this area. Every day, we develop new solutions and methods that enable us to build more efficiently and ambitiously with wood.