Crawl Space Encapsulation and Dehumidification Guide

A damp crawl space causes problems that reach the whole house: musty odors, mold, wood rot and higher humidity upstairs. The lasting fix is to seal the space from ground moisture and control humidity with a dedicated dehumidifier. Here is how crawl space encapsulation works.

Why Crawl Spaces Get Damp

Moisture enters a crawl space from the bare soil below, from outside vents that let in humid air, and from any plumbing leaks. Because crawl spaces are dark and poorly ventilated, that moisture lingers and feeds mold and wood decay. Encapsulation addresses the sources.

What Encapsulation Involves

1. Address any standing water and plumbing leaks first
2. Cover the floor and often the walls with a heavy vapor barrier, sealed at the seams
3. Seal or insulate the vents so humid outside air cannot pour in
4. Install a dedicated dehumidifier to control the remaining humidity

The Role of a Dehumidifier

A vapor barrier blocks ground moisture, but the air in a sealed crawl space still needs humidity control. A crawl space dehumidifier is built for the low clearance and conditions of these spaces and keeps the relative humidity low enough to prevent mold and rot. Look for a unit sized for the square footage and able to drain automatically.

Benefits of a Dry Crawl Space

• Less mold and musty odor reaching the living space
• Protection for wood framing and subfloor from rot
• Lower humidity in the home, since crawl space air rises
• Better energy efficiency and comfort upstairs

Maintain the System

An encapsulated crawl space is low maintenance, but check the dehumidifier filter and drain periodically and inspect the vapor barrier for damage. For larger or wetter spaces, an industrial dehumidifier handles the load. Browse our dehumidifiers for crawl space moisture control.