Condition of the building envelope is associated with indoor dampness, mould and musty odour, as well as moisture measured in floor joists

Interventions designed to reduced indoor dampness and mould have shown mixed results, suggesting that the causes of indoor dampness are not yet fully elucidated. Poor repair and infrequent maintenance have been demonstrated to be associated with indoor dampness and mould in several previous studies, as has age of the building, however these associations do not easily translate into specific interventions other than generally improving condition or maintenance of buildings. Using regression analysis in three New Zealand house condition surveys, the author demonstrated that the condition of five specific components of the building envelope (roof, windows, wall claddings, spouting and guttering and exterior paint) are associated, with a dose-dependent effect, to increased risk of indoor dampness, visible mould, musty odour and moisture measured in floor joists. It is also demonstrated that musty odour is strongly associated with subfloor defects (absence of sufficient ventilation, ponding or leaks and lack of a ground vapour barrier).