Definition
A vapor barrier is a membrane that blocks moisture from moving through walls and foundations. It's critical below-grade and on ground levels to prevent condensation and structural moisture damage. Think of it as your first line of defense against moisture problems.
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Vapor barriers are polyethylene, foil, or paint products blocking moisture movement. Critical on ground and below-grade surfaces. Cost varies from $0.50-2 per square foot. Prevents condensation and structural moisture damage. Application location depends on climate (cold vs. warm). Improper installation can trap moisture creating problems. Complements drainage and ventilation. Modern construction often uses vapor-permeable layers (retarders). Professional guidance ensures proper application.
Pro Tip
Work with professionals on vapor barrier placement; improper installation can trap moisture and create problems rather than solving them.
Example
A vapor barrier prevented condensation damage in a poorly ventilated basement.