This Bulletin on preventing dampness in houses covers some aspects that builders and subtrades may occasionally
be required to deal with . It is, however, also intended for general guidance to householders.
Finished basements in twenty-seven Ottawa houses were investigated to determine if the basement assemblies could contribute to poor indoor air quality due to molds. The wall cavities were inspected with optical fibrescopes to determine the composition and note the conditions. Visible mold colonies were sampled to identify mold species. The presence of molds correlated with the presence of chronic wetting events rather than any particular basement finishing techniques. Molds were analyzed from 16 (59%) of the houses and toxigenic molds were found in all houses except one.
Fifty nine houses, selected on the basis of previous measurements of mold levels, were subjected to field inspection, testing and monitoring and the occupants subjected to health evaluation questionnaires and testing of blood and nasal secretions. Data on house performance, mold growth and health has been compiled in an electronic data base available for future researchers. The work showed correlations between measurements of mold growth and immunological reactions of occupants and that mold growth appeared to be more related to local moisture sources than ventilation levels.