Crawl space sealing and encapsulation

Crawl space sealing, often called encapsulation, closes a vented crawl space off from outside air and covers the ground and walls with a sealed liner. For Rock Hill and York County homeowners with musty air, sweating ducts or damp insulation, it's the most thorough fix: no more humid air through the vents, no more moisture from bare clay, and a dehumidifier or conditioned air keeping the space dry.

What goes into the job?

1. Look first. Checking for water coming in, wood decay, insects, plumbing leaks and the state of the insulation and ducts.
2. Handle water. Gutters, grading or a sump and drain if the clay floor gets wet.
3. Clear it out. Removing old plastic, fallen insulation and debris.
4. Seal it up. Closing vents and gaps at pipes, wires and the access door.
5. Line it. A heavy ground liner with overlapped, taped seams, run up the walls and around the brick piers.
6. Control the air. Usually a dehumidifier, sometimes a supply-air connection.

Is it right for your house?

• The house smells damp, especially in summer
• Ducts or pipes drip under the floor
• Insulation is wet or falling
• The CL-100 or home inspection flagged moisture
• Mold or decay has come back after earlier repairs

Why it's common around Rock Hill

Many York County houses sit on brick or block foundations over a clay floor, from mill village homes near the old textile plants to brick ranches and newer subdivision houses. Summer humidity in a vented space plus clay that holds water is what sealing is meant to fix.

What does the SC code say?

South Carolina uses the 2021 International Residential Code with state modifications. For an unvented crawl space it calls for a continuous vapor retarder over the exposed earth, with joints overlapped at least 6 inches and sealed, edges carried at least 6 inches up the foundation wall and sealed, and one of several air options, including continuous exhaust, a conditioned air supply, or a dehumidifier sized at 70 pints a day per 1,000 square feet of floor.

What affects the price?

• Crawl space size, height and how hard it is to move around
• Liner thickness and how much of the walls and piers are covered
• Cleanup of old plastic and insulation
• Drainage needed first
• The humidity control method and electrical work
• Wood repairs found along the way

The contractor prices the job after an inspection. We don't publish prices.

Where you can get this done

• Rock Hill
• Fort Mill
• Tega Cay
• York
• Clover

Related services

• Vapor barrier replacement
• Crawl space dehumidifiers
• Rotted sill and joist repair
• Sump pumps and crawl space drainage

South Carolina licensing, the CL-100 moisture rules and York County soils are covered in the York County crawl space guide.