Humidity Control

Some signs show up in the crawl space itself: condensation on pipes or ductwork, a damp or musty smell, visible mold or mildew, insulation that’s wet or sagging, or wood surfaces that feel soft. Other signs show up in the living space above: musty odors, worsening allergy symptoms, or floors that feel slightly springy. High humidity in a crawl space often builds gradually, so by the time it’s noticeable, it’s usually been a problem for a while.

Ground moisture is the most common source. Even without standing water, soil releases moisture vapor that rises into the crawl space. Warm, humid outside air entering through foundation vents also significantly contributes, particularly in summer when the air below is cooler and condensation forms on surfaces. Plumbing leaks, poor exterior drainage, and inadequate or missing vapor barriers can all make the problem worse. In Bloomington’s climate, where summers are humid and rainfall is consistent throughout the year, crawl spaces without active moisture control tend to run damp.

In older building practice, venting crawl spaces was considered the right approach. The thinking was that airflow would carry moisture out. In practice, particularly in humid climates like Southern Indiana, venting brings in warm, humid air into the crawlspace, which is typically cooler in the summer. Warm, humid outside air enters the cooler crawl space and condenses on surfaces, which can make conditions worse rather than better. Sealing vents and managing the crawl space as a controlled environment is typically more effective.

Crawl space dehumidifiers are built specifically for the conditions found in that environment: low clearance, variable temperatures, higher moisture loads, and limited access for maintenance. They’re generally more durable, more efficient at the humidity levels found in crawl spaces, and designed to drain automatically rather than requiring a bucket to be emptied. A standard household dehumidifier placed in a crawl space is usually undersized for the job and not built to handle the conditions reliably over time.

Every crawlspace needs a vapor barrier! A dehumidifier is used in some situation, but not all. Our professional team will determine your specific needs after an inspection.

The units we install drain automatically, so you won’t need to empty a reservoir. That said, filters should be cleaned periodically, and the unit itself should be serviced occasionally to keep it running efficiently. We’ll walk you through the maintenance expectations for whatever system we install so there are no surprises.