An investigation of current British Columbian crawl spaces was funded in 1990-1991. A contractor inspected ten houses and tested the crawl space moisture levels and air leakiness, both to the outside and to the house above. The contractor also summarised the construction details of British Columbian crawl spaces, as designed, as build and as ideal. This study showed that current crawl space construction practice often lead to an excessive amount of moisture entry and ventilation of conditioned house air. The research results were used to promote code changes in both provincial and national building codes. The contractor revisited some of the test houses in 1993 to investigate the long-term success of remedial measures and canvassed the British Columbian inspectors and builders to see how code changes had affected crawl space construction practice. Application of new code clauses varied between municipalities.

KEYWORDS: Crawl space, Canada, moisture, air infiltration, codes of practice.