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Seal Crawl Space Vents - Control Moisture and Humidity

Now that you don't have any moisture from the earth, you donít need vents, which only made the moisture problem worse anyway, and drained you of energy dollars every month.

There are a several ways to seal crawl space vents. Since most vents take the place of one concrete block, you can knock them out and mortar a new block in. This is usually more work than necessary, so instead you can cover the openings outside with special-made exterior vent covers, available from Basement Systems Inc. You can also use rigid pieces of flat plastic. In any case, drill holes in the walls and screw or anchor them into the surrounding block around the vent, using caulk and or weather-stripping to keep the outside air out of your crawl space.

Alternatively, or in addition to exterior covers, a 2" thick foam block could be carefully cut and fitted into the vent opening on the interior and caulked.

Once the liner is in stalled and the vents and air openings to the outside are closed, your crawl space will begin to dry out. Over the days and weeks and months after the repair, your crawl space, its contents and floor framing will equalize to roughly the same humidity level as the upstairs.

US Department of Energy - Crawl Space Insulation

US Department of Energy - Crawl Space Moisture Control

Energy Star - Recommended Levels of Insulation for Crawl Spaces

North American Insulation Manufacturers - FAQs About Home Insulation