This research looks into the moisture behaviour of different timber-framed external wall structures under Nordic winter conditions. Wall structures were studied under laboratory conditions using new test equipment built in connection with the study. The test equipment can control indoor and outdoor conditions (temperature, relative humidity and pressure difference) as desired. The behaviour of structures can be monitored during tests under controlled conditions without disturbances. The design, building and testing of the new test equipment took about two years and one year was used to study wall structures.The study examined, for instance, the need for a vapour barrier in wall structures, and the impact of the difference in air pressure between the inside and outside of a building on the behaviour of structures. The study focused on two wall structure types: a cellulose insulation wall with a air barrier and mineral wool insulated wall with a vapour barrier.

• air barrier : convection and diffusion in walls
• experiment: hygrothermal performance
• HAM: experimental work : 8 wall sections

1. Drying of timber-framed wall structures
2. Estonian climate analysis for selecting moisture reference years for hygrothermal calculations
3. Hygrothermal calculations and laboratory tests on timber-framed wall structures
4. Indoor humidity loads and moisture production in lightweight timber-frame detached houses
5. Moisture and bio-deterioration risk of building materials and structuresL?hdesm?ki
6. Moisture behavior of timber-framed external wall structures in Nordic climate
7. Moisture transport in timber-framed external wall structures in Nordic climate - laboratory tests
8. Principles to analyze the moisture performance of timber-framed external wall assembly due to diffusion
9. The effects of ventilation systems and building fabric on the stability of indoor temperature and humidity in Finnish detached houses