How to Dehumidify Crawl Space Under House?

Dehumidifying a crawl space under your house is essential for preventing mold, wood rot, and improving air quality.

1. Assess Moisture Levels

Use a hygrometer to measure the humidity level in the crawl space.

Ideal humidity should be between 30-50%.

 

2. Seal the Crawl Space

Close all vents and gaps to prevent outside moisture from entering.

Use caulk or foam sealant to fill cracks around pipes, wiring, and walls.

 

3. Install a Vapor Barrier

Cover the crawl space floor and walls with 6-20 mil polyethylene plastic sheeting.

Overlap seams by 12 inches and seal them with waterproof tape.

This prevents moisture from rising through the ground.

 

4. Choose the Right Dehumidifier

Select a crawl space dehumidifier (usually low-profile and designed for small, confined spaces).

Make sure it's the correct pint capacity for your crawl space size. If you do not know how to choose the right capacity dehumidifier, please contact us for advice.

PREAIR sells the high-end whole house dehumidifier for sale. Welcome to consult!

 

5. Proper Placement

Position the dehumidifier in the center of the crawl space or near the moisture source.

Allow at least 12 inches of clearance around the unit for airflow.

 

6. Set the Ideal Humidity Level

Adjust the under house dehumidifier to maintain 40-50% RH.

Use a built-in humidistat if the model has one.

 

7. Drainage Setup

Connect a drain hose to the dehumidifier for continuous water removal.

Route the hose to a sump pump, floor drain, or outside the foundation.

 

8. Improve Air Circulation

Install crawl space fans or vents to improve airflow.

Use ducting if the dehumidifier supports it.

 

9. Regular Maintenance

Clean or replace air filters monthly.

Check for leaks or blockages in the drainage system.

Inspect the vapor barrier for damage.

 

10. Monitor Humidity Levels

Use a wireless hygrometer to track humidity without entering the crawl space frequently.