Getting rid of humidity under a house, especially in a crawl space, is crucial to prevent mold, wood rot, musty odors, and pest problems.

1. Fix Any Water Intrusion First

Before controlling humidity, stop the source of moisture:

Repair leaking plumbing pipes

Fix gutter and downspout issues so water drains away from the foundation

Ensure the soil around the house slopes outward

Seal gaps or cracks where outside water can enter

 

2. Improve Drainage Around the Crawl Space

Standing water keeps humidity high. Effective solutions include:

French drains around the house

Sump pump inside the crawl space

Ground drainage mats to channel water into the pump

 

3. Install a Vapor Barrier (Moisture Barrier)

Cover the soil with 6–20 mil thick polyethylene plastic:

Lay it across the entire ground

Overlap seams by 6–12 inches

Tape or seal the joints

Extend the barrier up walls (recommended)

A vapor barrier stops ground moisture from constantly evaporating into the crawl space.

 

4. Increase Airflow (if using a vented crawl space)

If your crawl space is ventilated:

Add vent fans

Ensure vents are not blocked

Improve cross-ventilation

However, in humid climates, vented crawl spaces often make humidity worse.

 

5. Encapsulate the Crawl Space (Most Effective Method)

Encapsulation means sealing the crawl space like a mini–basement:

Seal all vents

Install a high-quality vapor barrier on the ground and walls

Add insulation

Use a dedicated crawl space dehumidifier

This is the gold standard method to permanently control humidity.

 

6. Install a Crawl Space Dehumidifier

A regular home dehumidifier is not enough.
Use a low-temperature, high-capacity crawl space dehumidifier with:

Continuous drainage

Optional built-in pump (for long or upward drain paths)

Automatic humidity control

Set humidity to 50–55% for best protection.

Preair VT70E dehumidifier is recommended for you. It removes 70 pints of water per day under the condition of 26.7 ℃/60% RH. If you are interested in the unit, you can check more information from the article, Crawl Space Dehumidifier Sizing and Installation. Preair is a reliable dehumidifier manufacturer that provides high quality whole house dehumidifiers for sale. If you want to buy an under house dehumidifier, please contact us as soon as possible. In addition, we take customized orders if you are a dealer. Real production lines and workers, guaranteed quality, and reliable after-sales service are the reasons why we are worth choosing.

 

7. Insulate Pipes and Ducts

Humidity condenses on cold surfaces. Wrap insulation around:

Air ducts

Water pipes

HVAC equipment

This reduces condensation and lowers moisture levels.

 

Summary

To get rid of humidity under a house, remove water sources, improve drainage, install a vapor barrier, and manage moisture with ventilation or crawl space encapsulation plus a dedicated dehumidifier. The most reliable long-term fix is full crawl space encapsulation + dehumidifier.