A raised wood floor system separates a structure from one of the biggest sources of moisture — the ground itself.

With proper design, construction, and maintenance practices, a raised floor system can remain dry and free of moisture-related problems.

Moisture-related issues are among the most common problems faced in new home construction. Moisture management in raised wood floor construction should be addressed with shared attention to drainage, ventilation, insulation and vapor retarders.

preventing moisture under a raised floor house with ventilation

Drainage paths under and away from the home are critical, whether to basement construction or grade-level crawlspaces. Flood vents are required to be installed within enclosed crawlspaces of homes built in flood zones, providing pressure equilibrium to the foundation walls in the event of flooding.

Ventilation, whether natural or mechanical, is vital to the occupants’ health and the sustainability of the structure. Installation of a Class I vapor retarder over exposed earth under a raised wood floor will reduce code-required ventilation, though optimum foundation performance is provided by incorporating plentiful, rather than minimal, ventilation.

Conditioned/semi-conditioned crawlspace construction requires the vapor retarder to be continuous up the inside face of enclosing foundation walls, sealed to the walls within inches of the sill plate.