Moisture resistance of a number of types of building structures The structural features that have been investigated in this project have all been used in houses built in accordance with ecological aims, being intended to be environmentally responsible and with recycling/re use in mind. The five houses have been built without the use of plastic film in the walls or roof, with insulation provided by cellulose materials or aerated concrete, and can be regarded as unconventional. Most of them have enhanced passive stack ventilation systems. It has been interesting to study the features in the houses from the viewpoint of moisture resistance, as there is no, or only very little, previous experience of the performance of such features. The results from these field investigations give some idea of the moisture resistance of the houses, but no data suitable for generalising due to the small number of the sample examined. However, the results indicate shortcomings in moisture resistance in the roof and roof space structures in four of the houses. The fifth house showed no signs of such damage. The moisture loading is probably due to combinations of moisture diffusion and moisture convection from the interior of the houses and to residual building moisture. These two last sources are probably the most relevant in terms of being responsible for any damage, as long as the moisture input from inside the house is not too extreme. The conclusion from the work is that a moisture analysis is needed for structural features of this type, as it is for all structures, and in accordance with current knowledge. These ecological structures are no exception. There is no conflict between ecological building and a properly moisture resistant structure. The materials used in ecological building work perfectly well if they are correctly employed and as part of a system, which has been demonstrated in some of the houses in this investigation.