CLT and fire protection: How to build sustainably and safely

About the article

Please note that this article is about fire-safe construction according to Swedish building regulations. Are you building outside Sweden? Contact us for advice.

Function-based regulations

CLT is a renewable material that is increasingly used thanks to its excellent properties. Despite this, some are reluctant to use wood frames due to preconceived notions about the extra measures and costs that may arise. Daniel Anderson, specialist in construction technology, and Adam Kihlberg, head of technical business development, clarify the concepts.

- "What deters people from wood is that wooden frames may require expensive and extensive treatment to meet fire protection requirements. Additionally, insurance companies, lacking adequate information, may be hesitant when it comes to houses with combustible material in the frame. By understanding and managing these aspects, the construction industry can continue to develop and use wood as sustainable and safe building material," says Adam Kihlberg.

What are the advantages of CLT in terms of fire protection?
- "A strong argument for using CLT in the frame is that wood has a more predictable fire behaviour and more stable weakening during combustion compared to steel, which can change properties more significantly at high temperatures."

What does the regulation look like?
- "The fire protection regulations available via Eurocode and the Swedish National Board of Housing, Building and Planning's collection of regulations today are function-based, which means that they describe how the building should perform in the event of a fire, regardless of the material in the frame. The building engineer must design the building’s elements so that they meet these requirements, which can mean different solutions depending on the frame material. When building with a wooden frame, it is important to prevent the combustible wood from coming in contact with a fire. Measures such as well-executed installation routes, robust structural design, and fire cladding of load-bearing parts contribute to effective fire protection," says Daniel Anderson.

How can you work preventively in the planning stage?
- "A fire protection strategy should be established early in the construction process. All project participants, from the builder to contractors, must collaborate to ensure a good result. Combustible materials on the construction site require special consideration during the construction phase, and careful planning and well-executed assembly work are crucial for the building's fire safety," says Daniel.

By understanding and managing these aspects, the construction industry can continue to develop and use wood as sustainable and safe building material.

Adam Kihlberg, head of technical business development

Involve all parties early

We provide you with advice and suggestions to use during planning and design.

What about visible wood?
- "Visible wood surfaces do not automatically make a building more fire prone. The allowed area of visible wood is controlled by the building's fire classification. Fire impregnation and sprinkler systems can prevent visible wood surfaces from igniting or coming in contact with a fire, ensuring the building's integrity and enabling safe evacuation and firefighting," says Daniel.

How do insurance companies view new structures with wooden frames?-
- "Insurance companies currently lack clarity regarding property insurance in wooden buildings. According to several industry experts, we at Södra have the answer." says Adam.

What advice would you give before building with a CLT frame?
- "Choose the fire protection level according to the building's size, height, design, and type of activity. Involve us as a supplier of CLT early in the process so that we can convey our knowledge and make the best use of the material. Also, remember to involve the insurance company early to include any conditions from their perspective early on," says Adam.

Tips and advice for building with CLT

CLT is a fantastic material with great possibilities. Together with our partners, we can create buildings based on the most sustainable raw material source of all - Swedish wood from family forestry. By understanding and managing fire protection aspects, the construction industry can continue to develop and use wood as a sustainable and safe building material.