Foundation services
Crawl space encapsulation: liner, seal and dry
Crawl space encapsulation turns a vented crawl space into a sealed, unvented one: a continuous liner on the ground and up the walls, vents closed, and the air dried by exhaust, conditioned air or a dehumidifier.
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Written by HyreFoundation Research Desk Primary-source research and fact checking
The short answer
Crawl space encapsulation turns a vented crawl space into a sealed, unvented one: a continuous liner on the ground and up the walls, vents closed, and the air dried by exhaust, conditioned air or a dehumidifier. The model code spells out the minimum for the liner and the air. Water and structural problems come first.
Key takeaways
a continuous Class I vapor retarder, seams lapped 6 inches and sealed, run 6 inches up the wall.
The air still has to be dried or exchanged.
A liner over a pond is a hidden pond.
and combustion air before sealing.
What does an encapsulation job include?
Remove debris and old plastic. Fix drainage and any structural issues.
Heavy plastic over the ground and up the walls, seams lapped and taped, edges sealed.
Vents and rim gaps are sealed, and the access door made tight.
The 2012 code text lists exhaust at 1 cfm per 50 sq ft or conditioned supply air; many installers use a dehumidifier. Ask which your adopted code accepts.
What moves the price
Area and prep set the scope. We publish no price figures until we hold enough sourced, dated quotes; see what drives foundation costs.
| Factor | Why it changes the number |
|---|---|
| Square footage | Ground and wall area to cover. |
| Prep | Debris removal, drainage, mold treatment, repairs. |
| Drying method | Dehumidifier, exhaust fan or a supply duct. |
| Liner grade | Thicker, reinforced liners resist foot traffic. |
HyreFoundation publishes no national average price for this work. Depth to bearing, soil, access and method vary enough between two houses on the same street that a single figure would mislead.
Is encapsulation right for your crawl space?
In humid climates where a vented crawl space keeps condensing moisture, often yes. Our existing crawl space repair page covers the vented-versus-sealed research. Here the question is execution: does the plan meet the code minimum and dry the air?
What to ask before you sign
The full checklist is on choosing a foundation contractor.
Where this goes wrong
A sealed crawl space with no exhaust, supply or dehumidifier can stay humid.
Drain first. See crawl space drainage.
A furnace or water heater that pulls air from the crawl space needs a plan before vents close.
Get connected
Tell us about the work
Three short steps: the job, your home, and how to reach you. Nothing goes to a foundation company unless you agree.
A straight answer first. A person reads it and replies by email, free and with no obligation. Matching is not live yet, so this is not a quote. If a wall is moving or a door frame has racked out of square this week, call a structural engineer first.
Find a Foundation Professional
A person at HyreFoundation reads the request and replies. Matching is not live yet, so this is not a quote.
Questions
Is crawl space encapsulation worth it?
Does encapsulation need a dehumidifier?
How long does encapsulation take?
Can I encapsulate my own crawl space?
Written and audited by
HyreFoundation Research Desk
Primary-source research and fact checking
We read the model building code, the federal soil and moisture guidance and the insurer position ourselves, and we publish each figure with the document it came from and the date we retrieved it.
Where a number cannot be traced to a primary source, we say so instead of printing it. HyreFoundation does not inspect, engineer or repair foundations. Authorship is organizational: this desk, not a named persona.
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How this desk works
- Primary sources only. Code statements come from the International Residential Code, Chapter 4, as the model code. Soil statements come from USDA and USGS. Insurance statements come from the policy language and the Insurance Information Institute. We open the source rather than cite a blog that cites it.
- The code is a model, and adoption is local. Your jurisdiction adopts an edition and amends it, and foundation chapters are amended more than most because frost depth and soil are local facts. Every code figure says so.
- We hold no job data. We have no dataset of bids, pier counts or invoices, so no page claims an average from one. Calculators show the arithmetic and the inputs they assumed, and label the result as an estimate.
- We do not diagnose your house. A crack guide can tell you which pattern to measure and when to call a structural engineer. It cannot tell you whether your foundation is failing. An engineer on site does that work.
- We do not repair foundations, and we take no payment for placement, ranking or a favorable mention. Nobody buys a position on this site.
Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold. Our editorial policy sets out how we source, date and correct what we publish.
Sources & retrieval dates
Information on this page is general and varies with soil, climate, foundation type, building code, insurance policy and circumstance.
It is not engineering, insurance or legal advice, and no page can tell you whether your house has a structural problem: that needs a licensed professional on site.
HyreFoundation is an independent foundation resource, not a repair contractor or an engineering firm, and does not perform, supervise or warrant foundation work.