Crawl Space Insulation Cost (2026)
Insulating a crawl space costs $1,500 to $6,000, and most homeowners pay about $3,000. Fiberglass batts between the floor joists are the cheapest at $1 to $2.50 per square foot; rigid foam board on the walls runs $1.50 to $3.50; closed-cell spray foam is $2 to $5. Which surface you insulate matters more than which material — a vented crawl space insulates the floor, a sealed one insulates the walls.
- How much does it cost to insulate a crawl space?
- Crawl space insulation costs $1,500 to $6,000, with a typical 1,500 square foot space around $3,000. Fiberglass batts are $1 to $2.50 per square foot, rigid foam board $1.50 to $3.50 per square foot of wall, and closed-cell spray foam $2 to $5. Removing old insulation adds $800 to $3,500.
- Should I insulate the crawl space floor or walls?
- It depends on whether the crawl space is vented or sealed. A vented crawl space is outside the house thermally, so the insulation goes in the floor above it. A sealed, encapsulated crawl space is inside the house, so the insulation goes on the walls and rim joists and the floor is left open. Doing the floor in a sealed space wastes the money.
- Why does fiberglass fall out of crawl space floors?
- Moisture. In a humid vented crawl space the batts absorb water, get heavy and sag out of the joist bays. Wet fiberglass also stops insulating and holds moisture against the subfloor. Fallen batts are a symptom of a crawl space humidity problem, and replacing them like-for-like rarely lasts.
- Is crawl space insulation worth it?
- Usually, in cold and mixed climates — a cold floor above an uninsulated crawl space is one of the cheapest comfort complaints to fix. The bigger gain often comes from sealing the rim joist and the crawl space itself; insulation in a crawl space that is still damp and vented is the least durable version of the upgrade.
| What you're pricing | Low | Typical | High |
|---|---|---|---|
| Fiberglass batts between floor joists$1–$2.50 per sq ft; vented crawl spaces | $1,200 | $2,200 | $4,000 |
| Rigid foam board on the walls$1.50–$3.50 per sq ft of wall; sealed crawl spaces | $1,000 | $2,000 | $4,000 |
| Closed-cell spray foam on the walls$2–$5 per sq ft; air-seals as it insulates | $1,500 | $3,000 | $6,000 |
| Spray foam on the underside of the floorRarely the right choice; costly to undo | $3,000 | $5,500 | $9,000 |
| Rim joist sealing and insulationThe leakiest part of the crawl space | $300 | $800 | $1,500 |
| Add: remove old or fallen insulation$1–$2 per sq ft, bagged and hauled | $800 | $1,800 | $3,500 |
What drives the price
- Vented or sealed
- Decides where the insulation goes, and therefore how many square feet are being covered. Wall area is usually much smaller than floor area, which is why wall insulation is often cheaper.
- Material
- Batts are cheapest per square foot but fail in damp spaces. Foam board and spray foam do not absorb water and also act as an air barrier.
- Old insulation to remove
- Fallen or wet fiberglass has to come out first, and removal is priced separately.
- Clearance
- Low crawl spaces slow every task and raise labour on all of it.
Insulation is the last step, not the first
In a crawl space with a moisture problem, insulation goes in after the moisture is controlled. New batts in a damp vented space will sag and grow mold within a few seasons, which is how many crawl space cleanouts start.
The usual order is: fix drainage, lay a vapor barrier or encapsulate, then insulate the surface that matches the strategy. Many encapsulation quotes include wall insulation and rim joist foam — check before paying for it twice.
Common questions
- How much does it cost to insulate a crawl space?
- Crawl space insulation costs $1,500 to $6,000, with a typical 1,500 square foot space around $3,000. Fiberglass batts are $1 to $2.50 per square foot, rigid foam board $1.50 to $3.50 per square foot of wall, and closed-cell spray foam $2 to $5. Removing old insulation adds $800 to $3,500.
- Should I insulate the crawl space floor or walls?
- It depends on whether the crawl space is vented or sealed. A vented crawl space is outside the house thermally, so the insulation goes in the floor above it. A sealed, encapsulated crawl space is inside the house, so the insulation goes on the walls and rim joists and the floor is left open. Doing the floor in a sealed space wastes the money.
- Why does fiberglass fall out of crawl space floors?
- Moisture. In a humid vented crawl space the batts absorb water, get heavy and sag out of the joist bays. Wet fiberglass also stops insulating and holds moisture against the subfloor. Fallen batts are a symptom of a crawl space humidity problem, and replacing them like-for-like rarely lasts.
- Is crawl space insulation worth it?
- Usually, in cold and mixed climates — a cold floor above an uninsulated crawl space is one of the cheapest comfort complaints to fix. The bigger gain often comes from sealing the rim joist and the crawl space itself; insulation in a crawl space that is still damp and vented is the least durable version of the upgrade.
How we price this. Figures are national 2026 estimates built from contractor quote ranges, material pricing and regional labour rates, then cross-checked against published industry cost data. Reckon Home does not sell, broker or perform this work. Use these numbers to judge whether a quote is reasonable — not as a quote.