Is your crawl space vapour barrier still doing its job? Grab a flashlight and check from the hatch. Warning signs include bare dirt with no barrier, torn or shifted plastic, a barrier that stops at the floor instead of running up the walls, standing water on top of the plastic, sagging insulation, dark stains or white fuzz on joists, a musty smell upstairs and cold floors. Two or more signs usually mean a moisture problem. See all signs your crawl space vapour barrier has failed.