A compiled reference of 20 verified statistics on crawl space encapsulation costs in the United States: what a full encapsulation costs overall and per square foot, what each component runs (vapor barrier, insulation, dehumidifier, drainage, sealed vents), and what related moisture fixes cost. Every figure is drawn from a named cost source, This Old House and HomeAdvisor, and independently checked against the original before publishing.
Crawl space insulation cost by type
Installed cost per square foot by insulation material (This Old House).
Source: This Old House (thisoldhouse.com). Track spans $0 to $3.50 per square foot installed.
Key statistics
Key takeaways
Encapsulation is a mid-four-figure job built from a handful of priced components. The numbers below trace the total cost, what each piece runs, and the moisture problem it is meant to stop.
Crawl space encapsulation averages about $5,500 ($1,500 to $15,000).
Per square foot, it runs about $3 low, $7 average, $10 high.
Labor is 50% to 70% of the total; materials 30% to 50%.
A heavy 20-mil vapor barrier runs $0.40 to $0.70 per square foot.
A dehumidifier adds $800 to $2,000 installed.
Encapsulation stops the moisture that becomes mold, rot, and pests.
How we built this report
Every figure was compiled in September 2026 from named cost sources and verified against the original before publishing.
- Compiled from two independent cost guides
Encapsulation and component costs from This Old House and HomeAdvisor, which agree closely on the overall average.
- Broken down by component
Rather than a single lump sum, we itemize the vapor barrier, insulation, dehumidifier, drainage, and vent-sealing costs so the total is legible.
- Only explicitly stated figures
We include only numbers a named source states directly, and attribute each inline at the point it appears.
- Independent review
Written by one co-founder, reviewed by the other before publishing.
Scope note: these are national averages and ranges from consumer cost guides and vary widely by crawl space size, moisture severity, and region; they are directional, not quotes. This page covers crawl space encapsulation; basement water control is covered in our separate sump pump and waterproofing research, linked below.
Crawl space encapsulation, by the numbers
All 20 figures, grouped into three themes, each from a named cost source and independently verified against the original.
What encapsulation costs
The two leading cost guides agree closely on the headline number. According to This Old House (thisoldhouse.com) and HomeAdvisor (homeadvisor.com), crawl space encapsulation averages about $5,500, running $3 to $10 per square foot depending on moisture severity.
Statistic 1
Crawl space encapsulation averages about $5,500, with most homeowners paying $1,500 to $15,000.
This Old House / HomeAdvisor
Statistic 2
Per square foot, encapsulation runs about $3 on the low end, $7 on average, and $10 for extensive moisture problems.
This Old House
Statistic 3
Basic encapsulation runs $2 to $4 per square foot; more extensive work $3 to $10.
HomeAdvisor
Statistic 4
Labor accounts for 50% to 70% of the total, roughly $3,000 to $4,200.
HomeAdvisor
Statistic 5
Materials (vapor barrier, insulation, dehumidifier) make up the remaining 30% to 50%.
This Old House
What this means: Encapsulation is one of the rare exterior-adjacent projects where two independent guides land on nearly the same average ($5,500), which makes it a reliable budget line. Because labor dominates, the cost is driven more by how hard the crawl space is to work in than by the material bill, so access and moisture severity are the questions to ask a contractor.
Cost by component
A full system is a stack of priced parts. According to This Old House (thisoldhouse.com), the core is a heavy vapor barrier, insulation, a dehumidifier, and sealed vents, each with its own cost.
Statistic 6
A thin 4-mil vapor barrier runs about $0.05 to $0.20 per square foot.
This Old House
Statistic 7
A heavy 20-mil vapor barrier (standard for encapsulation) runs about $0.40 to $0.70 per square foot.
This Old House / HomeAdvisor
Statistic 8
A dehumidifier costs about $800 to $2,000 to install.
This Old House
Statistic 9
Fiberglass batt insulation is the least expensive, about $0.60 to $1.10 per square foot.
This Old House
Statistic 10
Spray foam insulation runs about $1.00 to $3.50 per square foot.
This Old House
Statistic 11
Rigid foam board insulation runs about $2.50 to $3.00 per square foot.
This Old House
Statistic 12
A full drainage system costs about $600 to $1,800 to install.
This Old House
Statistic 13
Sealing vents costs about $10 to $22 per vent.
This Old House
Statistic 14
Adding a crawl space access door costs about $60 to $150.
This Old House
What this means: The vapor barrier is the heart of the job, and the jump from a thin 4-mil sheet to a true 20-mil encapsulation barrier is the difference between a temporary cover and a sealed crawl space. The other components, insulation, dehumidifier, drainage, are added based on how wet the space is, which is exactly what an inspection determines before the quote.
Related fixes, and why it matters
Encapsulation often follows a moisture problem that already caused damage. According to This Old House (thisoldhouse.com) and HomeAdvisor (homeadvisor.com), the related fixes, mold removal and waterproofing, can rival the encapsulation itself.
Statistic 15
Mold removal in a crawl space runs about $500 to $4,000 depending on the extent.
This Old House
Statistic 16
Foundation waterproofing averages about $4,600, ranging $1,500 to $15,000.
HomeAdvisor
Statistic 17
Encapsulation prevents the damaging effects of moisture, mold, and temperature extremes.
This Old House
Statistic 18
It improves indoor air quality by sealing the crawl space off from the living space above.
This Old House
Statistic 19
It protects framing and the foundation against pest infestation and water damage.
This Old House
Statistic 20
A full encapsulation system is a vapor barrier, sealed vents, a dehumidifier, and dehumidification controls.
This Old House / HomeAdvisor
What this means: The economics only make sense next to the damage a wet crawl space causes: mold that reaches the living space, rot in the joists overhead, and pests that follow moisture. A $500-to-$4,000 mold bill and joist repair is the failure mode encapsulation prevents, which is why the crawl space, invisible as it is, belongs on a documented condition inspection rather than out of sight and out of mind.
Cite this study
Academic or press use: copy a ready-made reference. RapidEye is the publisher.
Quick FAQ
How much does crawl space encapsulation cost?
Crawl space encapsulation averages about $5,500, with most homeowners paying $1,500 to $15,000, according to This Old House (thisoldhouse.com) and HomeAdvisor (homeadvisor.com). Per square foot, it runs about $3 on the low end, $7 on average, and $10 for crawl spaces with extensive moisture problems.
What does crawl space encapsulation include?
A full system is a heavy vapor barrier over the floor and walls, sealed vents, a dehumidifier, and dehumidification controls, according to This Old House (thisoldhouse.com). A 20-millimeter vapor barrier runs about $0.40 to $0.70 per square foot, a dehumidifier $800 to $2,000 installed, and sealing vents $10 to $22 each.
How much does a crawl space vapor barrier cost?
A thin 4-millimeter vapor barrier runs about $0.05 to $0.20 per square foot, while a heavy 20-millimeter barrier runs about $0.40 to $0.70 per square foot, according to This Old House (thisoldhouse.com) and HomeAdvisor (homeadvisor.com). The thicker barrier is standard for a true encapsulation.
Why encapsulate a crawl space?
Encapsulation prevents the damaging effects of moisture, mold, and temperature extremes, improves indoor air quality, and protects framing and the foundation against pests and water damage, according to This Old House (thisoldhouse.com). Left open, a damp crawl space is a common source of rot, mold, and pest problems that surface elsewhere in the home.
Data sources
Every figure traces to one of these named sources, each checked against the original before publishing. We name each source and show its root domain, but do not hyperlink external sources; internal links stay live.
This Old HouseCrawl space encapsulation and component cost datathisoldhouse.com
HomeAdvisorCrawl space encapsulation and waterproofing cost datahomeadvisor.com