condensation

Rising moisture from the ground has caused quite a lot of damage on foundations of Swedish buildings, in particular for the type concrete slab on the ground. Some of these constructions may be repaired by mechanical ventilation, for example below the floor or below the concrete slab , if there is an air-permeable layer below the slab. Summarized results from a few field studies and tests, which have been going on for a period of 2-3 years, are reported. Different methods with mechanical ventilation systems have been found to work quite well so far, i.e.

This paper presents and discusses results of moisture transfer into timber frame constructions. The two mechanisms of transfer are diffusion and bulk air movement. Three defects in construction were monitored punctured vapour barrier, continuous path via an electrical socket and discontinuities at junctions. The study has shown that, under steady-state conditions condensation can take place, while under varying conditions both condensation and evaporation occur. This second case is typical of the building in use, and can prevent high levels of moisture existing in timber components.

The concern that a large number of housing units across Canada, and in particular, through Atlantic Canada are exposed to potential damage from wood rot due to moisture trapped within exterior walls caused a joint task force of Canada Mortgage and Housing Corporation and Canadian Home Builders Association representatives to address the "drying of walls" issue. Included in their mandate was a field research project in Atlantic Canada. The project, undertaken by Oboe Engineering Ltd. and AD1 Limited.

This paper discusses the use of trickle ventilators in the design for natural ventilation in dwellings. The discussion is based around the results of a field monitoring experiment where 17 out of 32 houses were fitted with trickle ventilators as a remedial measure to improve the distribution of ventilation and to reduce the occurrence of condensation. Reductions in condensation, effects on energy use, window opening and occupants views are considered. The paper concludes that trickle ventilators are a successful component part in the design of natural ventilation systems in dwellings.