Insulation Cost: Attic, Walls, and Spray Foam Prices

Attic insulation installation costs $1,700 to $2,100 on average for a standard home, while whole-house spray foam insulation averages $2,000 to $6,000 before any energy rebates, according to Angi cost data. The wide range reflects insulation type, the area being insulated, existing coverage, and regional labor rates.

How Much Does Insulation Installation Cost on Average?

The most common residential insulation job is adding blown-in insulation to an attic that is under-insulated. According to HomeGuide cost data, homeowners pay $1.00 to $1.50 per square foot for blown-in fiberglass or cellulose in an attic, inclusive of labor and materials. A 1,500 square foot attic floor therefore runs $1,500 to $2,250 installed.

Spray foam insulation in a crawl space or rim joist area costs considerably more per square foot but covers a smaller area. Dense-pack insulation in existing walls -- a job that requires drilling access holes and specialized blowing equipment -- runs $1.50 to $2.50 per square foot, per contractor pricing surveys.

Installed costs from HomeGuide and contractor pricing surveys. Board foot = 1 square foot at 1-inch thickness.

Attic Insulation Cost: Blown-In vs Batt

Blown-in insulation -- also called loose-fill -- is the standard for attic floors. It is installed using a blower machine that pushes shredded fiberglass or cellulose into the space, filling voids and conforming to irregular framing. According to Angi cost data, attic blown-in insulation runs $1,700 to $2,100 for a typical home before any utility rebates.

Batt insulation, the pre-cut fiberglass or mineral wool panels often used in open stud walls, is rarely the right choice for existing attics. Batts must fit precisely between joists and leave gaps at edges and obstructions. For retrofitting an under-insulated attic, blown-in is the industry standard.

Depth and R-value for blown-in: Fiberglass loose-fill achieves R-2.2 to R-2.9 per inch of depth. To reach R-49 (the DOE recommendation for most central US climate zones), you need approximately 17 to 22 inches of fiberglass. Cellulose achieves R-3.2 to R-3.8 per inch and reaches R-49 in 13 to 15 inches.

If your attic already has some insulation, the contractor will add material on top to bring the total to the target depth. Angi and HomeGuide cost data reflect whole-job pricing inclusive of setup and cleanup, not incremental add-only costs.

For homeowners comparing insulation work alongside HVAC replacement -- the two most common energy-efficiency projects -- see HVAC replacement cost for what heating and cooling system replacement adds to the picture.

Spray Foam Insulation Cost Per Square Foot

Spray foam is the premium-tier insulation choice. It comes in two forms:

Open-cell spray foam expands to fill cavities and provides good air sealing at R-3.5 to R-3.8 per inch. At $0.44 to $0.65 per board foot installed, open-cell is used in attic decks, interior walls for sound control, and areas where a vapor permeable product is needed. At 4 inches of depth it reaches roughly R-15.

Closed-cell spray foam is denser, provides R-6 to R-6.5 per inch, and acts as both air barrier and vapor retarder. At $1.00 to $1.50 per board foot, closed-cell is the standard recommendation for crawl space walls and rim joists, where moisture control and structural support are priorities. At 2 inches of depth it reaches R-12 to R-13 -- enough to meet code for most crawl space applications.

A typical crawl space spray foam job on 1,000 square feet of wall area at 2-inch closed-cell thickness runs $2,000 to $3,000 installed, per contractor pricing surveys. Whole-house spray foam -- spraying all attic, wall, and crawl space surfaces -- runs $5,000 to $10,000 or more on a typical 2,000 square foot home.

Wall Insulation Cost: Existing Walls vs New Construction

Insulating existing finished walls without opening them requires dense-pack insulation blown through holes drilled in the wall surface. Here is how the process works:

1. The contractor drills a 2-inch hole between each pair of studs, either from the exterior (preferable, avoids interior finishing work) or from the interior if exterior is inaccessible.
2. A nozzle is inserted and cellulose or fiberglass is packed under pressure until the cavity is full.
3. Holes are plugged with wood or plastic caps and the exterior surface is patched and repainted.

Dense-pack wall insulation costs $1.50 to $2.50 per square foot of wall area, per contractor pricing surveys. A 1,000 square foot wall area on a two-story home runs $1,500 to $2,500. Labor for patching and repainting exterior holes is not always included in an insulation contractor's quote -- confirm in writing.

New construction walls with open stud bays are far cheaper to insulate. Batt insulation runs $0.50 to $1.00 per square foot and does not require drilling or patching.

R-Value Requirements by Climate Zone

The US Department of Energy divides the country into eight climate zones. Required attic R-value increases with zone number:

• Zone 1 (Miami, Hawaii): R-30 minimum, R-38 recommended
• Zone 2 (Tampa, Phoenix): R-30 minimum, R-38 recommended
• Zone 3 (Atlanta, Dallas): R-30 minimum, R-38 to R-49 recommended
• Zone 4 (Washington DC, Kansas City): R-38 minimum, R-49 recommended
• Zone 5 (Chicago, Denver): R-49 minimum, R-60 recommended
• Zone 6 (Minneapolis, Boston): R-49 minimum, R-60 recommended
• Zone 7 (Duluth, Fairbanks interior): R-49 to R-60
• Zone 8 (Anchorage): R-60

Source: US Department of Energy Building Energy Codes Program. These figures are for new construction or when upgrading from no insulation. If your attic already has R-10, you are adding R-28 to R-50, not the full target amount.

If you are also evaluating whether your HVAC system is operating efficiently before investing in insulation, review repair vs replace your HVAC system to understand how insulation and equipment efficiency interact.

Does Insulation Installation Require a Permit?

In most US jurisdictions, adding insulation to an existing home does not require a building permit. The exception is spray foam insulation applied to the underside of roof decking (creating a conditioned attic), which changes the building's thermal envelope and may require a permit in some municipalities.

Confirm permit requirements with your local building department before scheduling work. The contractor should be able to advise, but ultimately the homeowner is responsible for determining permit obligations. For a broader guide to when permits are and are not required, see when do you need a permit for home improvement.

How to Compare Insulation Contractor Quotes

Get written quotes from at least three insulation contractors. Each quote should specify:

1. The insulation type and brand being installed
2. The target R-value and final installed depth
3. Whether the quote includes air sealing of gaps and penetrations before insulation is added (critical step that significantly affects real-world performance)
4. The square footage being covered
5. Any debris removal or old insulation disposal costs
6. Whether patching of drill holes (for dense-pack) is included
7. Their workmanship warranty

Air sealing is often sold as a separate line item but has a dramatic effect on energy performance. The DOE estimates that air sealing alone can reduce heating and cooling costs by 10 to 20 percent before any new insulation is added.

For guidance on vetting any contractor before signing, see how to get accurate contractor quotes for the full process of getting itemized, comparable estimates from competing installers.