Observation: Condensation is evident on the walls, earth, or floor insulation in the crawl space.
Performance Standard: Condensation in the crawl space shall not result from failure to provide adequate ventilation as required by code. Condensation resulting from other causes is not the responsibility of the remodeler.
Corrective Measure: The remodeler will ensure that ventilation meets the appropriate code requirements. Further reduction of condensation is an owner maintenance responsibility.
Discussion: Temporary conditions may cause condensation that cannot be eliminated by ventilation and a vapor barrier because: Night air gradually cools the interior surfaces of the crawl space. In the morning, moisture picked up by sun-warmed air is carried into the crawl space and condenses on cool surfaces.
At night, outside air may rapidly cool foundation walls and provide a cool surface on which moisture may condense.
If the house is left unheated in the winter, the floors and walls may provide cold surfaces on which moisture in the warmer crawl space air may condense.
Excessive moisture inside a heated house may hit the dew point within or on the colder bottom surface of vapor-permeable floor insulation. The condensation can be reduced by placing a vapor barrier between the insulation and the floor sheathing.
If condensation must be entirely eliminated, the owner can do so by sealing and dehumidifying or heating the crawl space, or by heating and dehumidifying the house.
