What crawl space encapsulation means
Crawl space encapsulation seals the crawl space floor and walls with a heavy vapor barrier, closes the vents and controls humidity, usually with a dehumidifier.
Where it matters on a waterproofing job
Vented and sealed crawl spaces follow different code paths, so closing vents is not a casual choice. Quote the liner thickness, the drainage and the dehumidifier as separate lines.
What the model code says
- Vented crawl spaces need at least 1 square foot of vent opening for each 150 square feet of crawl space. (IRC 2021, Chapter 4)
- The vent area can drop to 1/1,500 of the crawl area where the ground is covered with a Class I vapor retarder. (IRC 2021, Chapter 4)
Check which code edition your building department enforces for crawl space encapsulation before you quote.
What it costs
The crawl space encapsulation cost guide has the typical job at $5,500 and the usual range at $1,500 to $15,000. The guide shows its sources and what moves the price. The crawl space encapsulation cost calculator prices a job line by line.
Work it out
- Free calculator: Crawl space encapsulation cost calculator
- Cost guide: Crawl space encapsulation cost
- Tools, templates and guides: Free waterproofing resources
Sources: 2021 International Residential Code, Chapter 4, Foundations (ICC). Checked October 9, 2026.