How much does crawl space insulation cost?
How much does crawl space insulation cost?
$1.00 – $4.50 cost per square foot installed
$500 – $3,700 average total cost
Crawl space insulation cost
Crawl space insulation costs $1.00 to $4.50 per square foot or $500 to $3,700 on average. Spray foam insulation under a house costs $2 to $5 per square foot. Replacing insulation in a crawl space adds $1 to $2 per square foot for old insulation removal.
| Square feet | Cost to insulate the walls* | Cost to insulate the subfloor |
|---|---|---|
| 700 | $330 – $1,500 | $700 – $3,150 |
| 1,000 | $420 – $1,900 | $1,000 – $4,500 |
| 1,200 | $450 – $2,000 | $1,200 – $5,400 |
| 1,500 | $480 – $2,200 | $1,500 – $6,800 |
| 2,000 | $540 – $2,400 | $2,000 – $9,000 |
| 2,500 | $600 – $2,700 | $2,500 – $11,300 |
*Based on a 3' high crawl space
Average cost to insulate a crawl space
The following table shows the average cost to insulate a crawl space:
| National average cost | $1,800 |
| Minimum cost | $320 |
| Maximum cost | $10,000 |
| Average cost range | $500 to $3,700 |
*Cost data is from research and project costs reported by HomeGuide members.
Cost to install insulation under house by type
Installing insulation under a house costs $500 to $3,700, depending on the type and location.
Insulating the subfloor and rim joists is best in vented spaces.
Insulating the walls and rim joists is ideal in closed, unvented areas.
Insulating the subfloor, walls, and rim joists are recommended in cold climates.
| Insulation type | Crawl space location | Cost per square foot | Total cost installed* |
|---|---|---|---|
| Closed-cell spray foam insulation | Walls + subfloor | $2.00 – $5.00 | $850 – $6,700 |
| Rigid foam board | Walls | $1.20 – $3.70 | $500 – $1,600 |
| Rigid foam board | Subfloor | $1.20 – $3.70 | $1,200 – $3,700 |
| Blown-in | Subfloor | $1.00 – $2.80 | $1,000 – $2,800 |
| Roll and batt (fiberglass, rockwool) | Subfloor | $0.90 – $1.40 | $900 – $1,400 |
*Average total for a 1,000 SF crawl space with 3' high walls.
Rigid foam board can be expanded polystyrene (EPS), extruded polystyrene (XPS), or polyisocyanurate (Polyiso, ISO).
Roll and batt insulation may be fiberglass, Rockwool, natural fibers, or plastic. Roll and batt is best reserved for subfloors in dry, conditioned spaces.
Fiberglass batt insulation is the most common but the most problematic in vented crawl spaces. Fiberglass comes loose over time and also absorbs moisture, reducing its insulating value and potentially causing mold and structural damage.
Blown-in insulation is not typically recommended for crawl spaces but may be useful in spaces too tight for other insulation.
Spray foam insulation for crawl space cost
Spray foam insulation costs $2 to $5 per square foot for a crawl space. Spray foam insulation under a house works best when combined with rigid foam board insulation. Closed-cell spray foam is ideal for sealing subfloor gaps and insulating and sealing the floor joists.
| Pros | Cons |
|---|---|
|
|
Closed-cell foam is preferred for crawl spaces because it has a higher R-value per inch and provides a moisture barrier. Open-cell foam allows moisture in and is better for above-grade applications.
Crawl space insulation cost calculator
| Factor | Cost per square foot |
|---|---|
| Insulation materials | $0.50 – $3.20 |
| Installation labor | $0.50 – $1.30 |
| Total cost to install | $1.00 – $4.50 |
The following factors affect the cost:
Area size – The square footage and wall height affect the material and labor required.
Accessibility – Ease of access affects the labor cost. Jobs in hard-to-reach areas typically take longer to complete.
Type of insulation – Roll and batt insulation is cheaper than rigid foam board. Spray foam is the most expensive.
Faced vs. unfaced – Faced insulation batting costs $0.10 to $0.25 per square foot more than unfaced insulation and contains a vapor barrier.
Geographical location – Homes in climates with extreme temperature changes require thicker insulation, which costs more.
Vented vs. unvented space – Insulating a vented crawl space may require additional sealing to meet current building codes.
Old insulation removal – Removing and disposing of old insulation costs $0.75 to $2.00 per square foot.
Preparation – Spray foam requires a clean and dry surface. Cleaning and preparation may increase the labor time.
Cost to insulate crawl space walls vs. underside of the house floor
Insulating crawl space walls costs $420 to $1,900 for a 1,000 square foot space with 3' high walls. Insulating the underside of the house floor in the same space costs $1,000 to $4,500.
Insulate the subfloor and rim joists when the crawl space is vented.
Insulate the walls and rim joists when the crawl space is unvented or contains HVAC ducting.
Crawl space insulation prices by R-value
R-value is the measurement of a material's heat resistance. The higher the R-value, the better the insulator. The recommended R-value for crawl spaces depends on the climate and local building codes.
| R-value | Foam board | Closed-cell spray foam | Roll and batt |
|---|---|---|---|
| R-6 to R-7 | $1.00 – $1.80 | $1.50 – $2.50 | $0.70 – $1.00 |
| R-12 to R-14 | $1.50 – $2.50 | $2.00 – $3.80 | $0.90 – $1.20 |
| R-18 to R-21 | $2.20 – $4.00 | $3.00 – $4.50 | $1.00 – $1.30 |
| R-22 to R-30 | $2.80 – $4.60 | $4.00 – $5.50 | $1.10 – $1.50 |
*All prices are cost per square foot installed.
Labor cost to install insulation in crawl space
The labor cost to install insulation in a crawl space is $0.50 to $1.30 per square foot, depending on the insulation type. Batting is quick to install. Spray foam needs more prep time but installs faster than foam board, which requires sizing, cutting, and sealing each piece.
Crawl space cleaning and repairs
Crawl space cleaning and repairs cost $500 to $8,000, depending on the condition. Repairs may include vent and foundation repair, mold removal, pest control, and more. Cleaning and repairing the space is essential to ensure the new insulation does not mask underlying problems that could worsen over time.
Crawl space vapor barrier or encapsulation
Crawl space encapsulation costs $3,000 to $8,000 and is recommended for homes in areas with high moisture levels. Installing a vapor barrier costs $1,200 to $4,000. When using unfaced fiberglass insulation, lining the crawl space first with a vapor barrier adds a layer of moisture control.
DIY cost to insulate a crawl space
The DIY cost to insulate a crawlspace is $150 to $700. Hiring a professional is recommended to ensure there are no water damage or pest issues, all gaps are sealed, and the new insulation is installed correctly.
Effectively insulating a crawl space includes:
Getting rid of all water sources
Removing old insulation
Using mold-resistant, waterproof insulation
Insulating the walls instead of the ceiling
Sealing all vents, gaps, and hatchways
Sealing rim joists with boards or closed-cell spray foam
Installing a vapor barrier on the floor
Removing any built-up moisture with a dehumidifier once the installation is complete
Crawl space insulation FAQs
Should a crawl space be insulated?
Yes, a crawl space should be insulated. Uninsulated crawl spaces are a common source of unconditioned air infiltrating the home. Cold floors, high energy bills, and freezing or bursting pipes are signs the home needs better crawl space insulation.
What are the benefits of insulating a crawl space?
Benefits of insulating a crawl space include:
Prevents cold floors and drafts along the baseboards
Improves indoor air quality and comfort
Reduces energy bills
Keeps out pests and rodents (closed-cell spray foam)
Adds a moisture barrier (closed-cell spray foam)
Prevents frozen pipes
What R-value for crawl space floor insulation?
The recommended R-value for crawl space floor insulation is R-13 to R-30, depending on the home's geographical location. The colder the climate, the higher the recommended R-value.
What is the best type of insulation for a crawl space?
The best type of crawl space insulation is a combination of rigid foam and closed-cell spray foam. Both types provide insulation and an air and moisture barrier when adequately sealed. The best place to install the insulation depends on accessibility and whether the space is vented or unvented.
Vented – Insulate the subfloor or crawl space ceiling with rigid foam. Seal subfloor gaps and rim joists with spray foam and insulate ductwork and pipes before installing the subfloor insulation.
Unvented – Use sealed rigid foam on the crawl space walls. Use spray foam to air seal and insulate the rim joist. In cold climates, insulating the subfloor is also recommended.
Can you use spray foam insulation in a crawl space?
Spray foam insulation can be used in a crawl space. Still, many experts recommend against using it as the only insulation because it makes future underfloor repairs challenging to access.
Tips for hiring an insulation company
Before hiring an insulation contractor to insulate your crawl space:
Get at least three estimates to compare.
Look for pros experienced in crawl space insulation.
Read their reviews on HomeGuide and Google.
Select companies that are insured, bonded, and have been in business for 5+ years.
Ask for references.
Avoid selecting the lowest quote as quality may suffer.
Get a detailed estimate, contract, and warranty in writing before the work begins.
Never pay in full before the project starts. Use a payment plan instead for work completed.
Questions to ask
Are you licensed, bonded, and insured?
How long have you been in business?
What experience do you have with crawl space insulation?
What type of insulation do you recommend for my crawl space, and why?
What is and is not included in the estimate?
What additional costs should I expect?
How long will the installation take?
How long should the insulation last?
Is there a warranty, and if so, what does it include?
Are there rebates available, and do you apply for them?