Increased climate resilience for large wooden roofs

Large buildings in wood can be a good climate measure (reduction of greenhouse gas emissions) and the use of wood as a structural material in buildings is increasing. But increased use of wood in buildings can be a risk in a future more humid and warmer climate.

Sloped wooden ceilings are built with an air gap between the roof covering and the ceiling. There are two main reasons why the wood ceilings need to be ventilated: One is to prevent temperature rise on the roof covering that can cause snow melting and icing in gutters and downlets, while the other is that excess moisture must be ventilated out of the structure.

In the building industry's knowledge system Byggforskserien, there are currently only recommendations for air cavities for wooden ceilings up to 15 meters in length with slopes higher than 10-15°. When the recommendations were made, the experience was that there was trouble ventilating excess of heat if the roof was longer. Based on new measurements and calculations, a PhD thesis in Klima 2050 concludes that it is possible to build both longer and more low sloped roofs than previously recommended. New recommendations are implemented in the partners' building systems. The findings were presented at several Fagtreff about roofs under the auspices of the Byggforskserien (SINTEF) in the four largest cities in the country with an audience of nearly 500 people from the industry.

ZEB Laboratory will be built at NTNU‐campus in Trondheim with a wood constructed 19 m long BIPV roof. The building is suitable for monitoring of temperature, humidity and air velocity inside the air cavity beneath the PV roofing. Illustration: LINK Arkitektur/Veidekke.

ZEB Laboratory will be built at NTNU‐campus in Trondheim with a wood constructed 19 m long BIPV roof. The building is suitable for monitoring of temperature, humidity and air velocity inside the air cavity beneath the PV roofing. Illustration: LINK Arkitektur/Veidekke.