Most crawl space encapsulation jobs cost $5,000 to $15,000, according to HomeAdvisor, and the size of the crawl space floor drives most of that. Our own ballpark for a 1,500 square foot crawl space with a 12 mil liner and a dehumidifier is $6,650–$9,200. Every price on this page is a ballpark, not a quote. The firm number comes after we have been under the house.
What do we charge by size?
Full encapsulation runs about $3.50 a square foot of crawl space floor with us, with a job minimum of $2,500. The examples below assume our standard 12 mil liner and a crawl space dehumidifier.
| Crawl space floor | Our ballpark |
|---|---|
| 1,000 sq ft | $4,900–$6,800 |
| 1,500 sq ft | $6,650–$9,200 |
| 2,000 sq ft | $8,350–$11,650 |
Each row is a range because two crawl spaces of the same size rarely take the same work. If you don’t know your square footage, start with the footprint of the house and leave out any porch, garage or addition that sits on a slab.
Before we quote, we measure the humidity in the crawl space and the moisture in the wood. Those two readings tell us whether the job needs more than a liner and a dehumidifier.
What do national sources say?
Published ranges are wide because they lump small dry jobs in with big wet ones. This is what four sources said when we checked in October 2026:
| Source | What it says |
|---|---|
| HomeAdvisor (2025) | Average about $5,500. Most jobs $5,000–$15,000. Basic work $2–$4 a sq ft, extensive work $3–$10. |
| This Old House (March 2026) | $1,500–$15,000, or $3–$10 a sq ft, averaging about $7. A 1,000 sq ft crawl space: $3,000–$7,000. |
| Fixr (2025) | $2,000–$15,000, or $2–$6 a sq ft. |
| Upstate Structural Repair | About $5 a sq ft, from an Upstate SC contractor. |
HomeAdvisor also puts labor at 50 to 70 percent of the price. That is why the condition of the crawl space matters as much as the materials, and why two quotes for the same square footage can be far apart.
What drives the price?
Size sets the base. After that, the price depends on how hard the space is to work in and what has to be fixed before the liner goes down.
- Size. We price by the square foot of floor. Taller foundation walls take more liner.
- Liner. Our standard is 12 mil, with 20 mil as an option. Our guide to choosing a vapor barrier thickness covers when the heavier sheet earns its cost.
- Headroom. A crawl space you can crouch in goes faster than one where the crew works on their backs under ducts and pipes. With labor the biggest share of the bill, low clearance costs money.
- Water. Standing water has to be dealt with before a liner goes in. On sloped lots around Keowee and Hartwell, water tends to run along the surface of the clay toward the downhill side of the house. Our page on crawl space drainage and sump pumps explains the fix.
- Debris and old insulation. We clear debris and pull down wet or fallen insulation. Some crawl spaces need a few bags hauled out. Others need a full day of cleanup first.
- Dehumidifier. Our size examples include one, installed with a condensate drain. See crawl space dehumidifier installation for what that involves.
- Mold. Mold on the framing gets treated before the space is sealed.
- Permit. Oconee County requires permits for alterations, including electrical work, and a new circuit for a dehumidifier is electrical work. Inside Seneca city limits, the City of Seneca has its own building official.
What do add-ons cost?
Here are our estimator figures beside the national ranges. Ours are Upstate ballparks, not quotes.
| Add-on | Our ballpark | National range |
|---|---|---|
| 20 mil liner instead of 12 mil | $0.40 more per sq ft | Not listed |
| Crawl space dehumidifier, installed | $1,600 | $800–$2,000 with wiring (This Old House); $750–$1,700 (Fixr) |
| Drain line and sump pump | $2,200 | $600–$1,800 (This Old House) |
| Treating mold on the framing | $900 | $500–$2,000 (Fixr) |
| Foam board on foundation walls | $2.75 per sq ft of wall | $2.50–$3.00 per sq ft (This Old House) |
| Pulling down old floor insulation | $0.60 per sq ft | $300–$1,000 a job (Fixr) |
| Permit | Set by the county or city | $100–$250 (This Old House) |
Foam board on the walls comes with a South Carolina rule: in heavy termite areas, the code requires a 6-inch inspection gap where foam plastic is used on foundation walls (SC Reg. R-8-1216).
Is a vapor barrier alone cheaper?
Yes. Our barrier-only rate is about $2 a square foot with a $1,500 minimum, or roughly $2,000–$2,750 for 1,000 square feet. Fixr puts a vapor barrier alone at $1,500–$4,000.
The catch is that a liner by itself may not keep the space dry. In the Advanced Energy field study, vented crawl spaces that already had a full 6-mil ground cover still sat above 70% relative humidity for 98% of the summer. Our comparison of encapsulation vs. a vapor barrier goes through the difference.
How do I get a price for my house?
Put your square footage and what you have seen down there into our crawl space encapsulation estimator for a ballpark range, or give us a call. When you are ready, we measure under the house and turn the ballpark into a firm price.
