Durable building structures are, in general, associated with low moisture conditions in and around the building components. Indeed, this is a fact when considering organic building components like timber and wood products. A rule of thumb states that wood moisture content should be below 20% by weight at any time to prevent degradation due to fungal attacks (Cartwright and Findlay, 1958). At moisture contents above the fibre saturation point (28-30%) and temperatures between 0 and 45 ˇăC the risk of fungal attack increases considerably (Zabel and Morrell 1992). Risk of wood degradation caused by fungal attacks put high demands on the design of durable wood based buildings. This is a well-known fact in traditional timber frame buildings, and hence, vapour barriers are used extensively in the Nordic Countries. A combination of lightweight concrete (LWC) and timber frame walls are often used as an alternative to traditional timber frame walls. The inner cellular concrete wall is load bearing, whereas the timber frames support only the outer claddings.

An experimental programme financed by the Danish Forest Product Development Fund has been carried out to investigate the moisture conditions in combined LWC and timber frame walls. The programme contains theoretical and experimental investigations as well as field surveys of existing buildings based on this type of construction. The experimental investigations include laboratory tests carried out in a hot box suitable to test walls at welldefined climate conditions. Also, full scale-tests are carried out on walls built in a test house where the indoor climate is controlled and the outdoor climate is natural. Results from the experimental programme can be found in Stang (2002). Presented in the present paper are results from one of the lab tests on 9 different wall constructions based on LWC on the inside and exterior claddings. Also, results using simple calculations based on well-known models are presented.

• concrete
• experiment: field testing and monitoring programs : test house
• experiment: hygrothermal performance
• HAM: application
• vapor barrier, vapor retarder
• wood frame houses and walls, wood structure

1. On the influence of cavity ventilation on moisture content in timber frame walls  

1. On the influence of cavity ventilation on moisture content in timber frame walls
2. Protection of wood by design  

1. Building-related symptoms and molds: a two-step intervention study
2. Health evaluation of volatile organic compound (VOC) emissions from wood and wood-based materials
3. Measuring moisture content in wood with built in probes 20+ years experience
4. Numerical method for calculating latent heat storage in constructions containing phase change material
5. On the influence of cavity ventilation on moisture content in timber frame walls
6. Protection of wood by design
7. Symptoms associated to work in a water damaged school building
8. TDR measurement of moisture content in aerated concrete