How much does it cost to insulate a house?

A full insulation project for a 2,000 square foot home typically runs $3,500 to $10,000 depending on insulation type and how many areas are being insulated. Attic-only insulation is the most common project and costs $1,500 to $4,000. Wall insulation for an existing home is significantly more expensive due to the need to open drywall or use blown-in injection methods.

What is the cheapest type of home insulation?

Fiberglass batt insulation is the least expensive option at $0.30 to $1.00 per square foot installed, not including any associated work. Blown-in fiberglass or cellulose is similarly priced and better suited to existing spaces. Spray foam is 3–8x more expensive but provides air sealing simultaneously.

Is spray foam insulation worth the extra cost?

Spray foam is worth the premium in two situations: new construction where the air-sealing benefit from the start saves energy costs for the building's lifetime, and in specific problem areas like rim joists, crawl spaces, and attic hatches where air infiltration is the dominant heat-loss mechanism. For standard attic insulation top-up, blown-in cellulose or fiberglass is almost always more cost-effective.

How long does home insulation take to pay back?

Attic insulation typically delivers an energy cost payback in 3 to 7 years — one of the best ROIs of any home improvement. The payback period depends on your current insulation R-value, local energy costs, and heating/cooling system efficiency. In cold climates with high energy costs (Northeast, Midwest), payback can be as fast as 2–3 years.

Do I need a permit to add insulation?

Adding insulation to an attic or crawl space typically does not require a permit. Spray foam insulation in enclosed wall cavities may require inspection in some jurisdictions because it's considered a structural and fire-safety concern. Check with your local building department before starting any spray foam project inside walls.

Home Insulation Cost Guide 2026: What Every Insulation Type Actually Costs

April 29, 2026 · Cost Guide · 5 min read

Home insulation costs $1,500 to $6,500 for the most common projects — attic top-ups and crawl space encapsulation — and can reach $15,000 to $25,000 for a whole-house spray foam installation. The range is so wide because insulation type, R-value target, accessibility, and whether existing material needs removal all drive price independently. Based on our directory of insulation contractors nationwide, the single biggest variable after type is the contractor's travel distance and regional labor market.

Cost by Insulation Type

Blown-In Fiberglass or Cellulose (Most Common)

Blown-in insulation is the standard choice for adding R-value to an existing attic. A truck-mounted blower fills the cavity evenly without requiring removal of existing batts (in most cases).

Blown-in cellulose: $0.50–$1.50 per square foot installed
Blown-in fiberglass: $0.60–$2.00 per square foot installed
Typical attic project (1,200 sq ft floor): $1,500–$3,500

Cellulose uses recycled paper fiber and has a slightly higher density that reduces air movement within the insulation layer. Fiberglass blown-in is non-combustible and performs better in humid environments. Both reach the same R-values at similar depths — the choice often comes down to contractor preference and local material availability.

Fiberglass Batt Insulation

Batts are pre-cut panels installed between studs, joists, and rafters. They're the standard for new construction and accessible spaces but not appropriate for existing finished walls without opening drywall.

R-13 (2x4 wall): $0.30–$0.65 per square foot installed
R-19 (2x6 wall or floor joist): $0.50–$0.90 per square foot installed
R-38 (attic, new construction): $0.70–$1.30 per square foot installed
Full attic batt installation (1,200 sq ft, new): $2,000–$4,500

Mineral wool (Rockwool/stone wool) batts cost 15–30% more than fiberglass but offer superior fire resistance, better sound attenuation, and don't compress over time. For interior sound insulation between rooms or fire separation assemblies, mineral wool is often worth the premium.

Spray Foam Insulation

Spray polyurethane foam (SPF) comes in two varieties with very different applications and costs:

Open-cell spray foam (R-3.7 per inch): $0.50–$1.50 per square foot installed — softer, vapor-permeable, excellent for interior walls and roof decks in humid climates
Closed-cell spray foam (R-6.5 per inch): $1.50–$3.50 per square foot installed — rigid, vapor barrier, structural reinforcement, the gold standard for rim joists and crawl spaces

A full attic conversion from blown-in to open-cell spray foam applied to the roof deck (unvented attic assembly) typically costs $4,500 to $10,000 for a 1,500 sq ft attic. Rim joist spray foam — one of the highest ROI applications — costs $800 to $2,500 for a typical home.

Rigid Foam Board

Rigid foam boards (EPS, XPS, polyiso) are used where thickness is constrained — basement walls, under slabs, roof assemblies above sheathing. They cannot be used in open cavities without a thermal barrier (drywall) over them due to fire code requirements.

EPS (expanded polystyrene): $0.25–$0.50 per square foot material cost; R-4 per inch
XPS (extruded polystyrene, e.g., pink board): $0.35–$0.65 per square foot material; R-5 per inch
Polyiso: $0.40–$0.80 per square foot material; R-6 to R-6.5 per inch
Installation adds: $1.00–$2.00 per square foot labor

Cost by Project Area

Attic Insulation

The attic is the highest-priority insulation project in most homes — heat rises, and an underinsulated attic is the single largest source of energy loss in older construction. Target R-value for attics: R-49 to R-60 in cold climates (Zones 5–8), R-38 to R-49 in mixed climates (Zones 3–4).

Attic air-seal + blown-in to R-49 (1,200 sq ft floor): $2,000–$4,500
Attic removal of old damaged insulation + replacement: Add $1,000–$3,500 for removal and disposal
Whole attic spray foam (unvented assembly): $5,000–$12,000

Wall Insulation (Existing Homes)

Insulating existing finished walls without demolition requires blown-in injection through small holes drilled from interior or exterior. This is significantly more expensive than attic insulation:

Dense-pack cellulose injection (per 100 sq ft of wall): $500–$1,200
Full exterior wall insulation (1,500 sq ft ranch, all walls): $5,000–$14,000

If you're opening walls for any other reason (electrical upgrade, plumbing, remodel), insulating at the same time dramatically reduces the per-square-foot cost by eliminating the need to drill and patch separately.

Crawl Space

Crawl space strategy depends on whether the space is vented or unvented. The modern approach for most climates is full encapsulation — sealed vapor barrier, insulated walls, and conditioned air supply — rather than floor insulation above a vented crawl space.

Floor joist batt insulation (vented crawl): $1,500–$4,000
Crawl space encapsulation + wall insulation: $4,000–$10,000
Crawl space spray foam walls (closed-cell): $3,000–$7,500

Basement Walls

Closed-cell spray foam on concrete walls (2-inch): $2,500–$6,000
Rigid foam + framed wall with batts: $3,000–$7,500
Rim joist spray foam only: $800–$2,500 — excellent ROI, often ignored

What Affects the Final Quote

Insulation quotes vary significantly between contractors. Factors that legitimately drive cost up:

Existing insulation removal: Damaged, pest-contaminated, or asbestos-containing old insulation adds $0.50–$2.00/sq ft for removal and disposal
Air sealing work: Properly air-sealing an attic before blowing in new insulation adds $300–$800 but dramatically improves the performance of the new insulation
Difficult access: Low-slope roofs, tight crawl spaces, and knee walls add 20–40% to labor
Hazardous materials: Vermiculite (possible asbestos) in old attics requires abatement before any new work; costs $2,000–$10,000 for testing and removal

Energy Efficiency Incentives

The federal Residential Clean Energy Credit (25C) covers insulation upgrades at 30% of project cost, capped at $1,200 per year through 2032. Combined with state utility rebates — which range from $0.05 to $0.15 per square foot in many states — effective out-of-pocket cost is commonly 30–45% below the quoted price. Ask your contractor to provide documentation for the tax credit before work begins.

Getting Accurate Quotes

For insulation projects, get at least three quotes. The range between the lowest and highest bidder on an identical scope frequently exceeds 40%. Use the guide to getting and comparing contractor bids to evaluate quotes side by side — pay particular attention to the specified R-value target, air sealing scope, and whether removal of existing material is included or excluded.

Verify that your insulation contractor carries general liability insurance (minimum $1 million) and is licensed in your state for insulation work — check requirements with our contractor license requirements by state guide. Find insulation contractors in your city or search for contractors near you with verified credentials and customer reviews.

Frequently Asked Questions

How much does it cost to insulate a house?: A full insulation project for a 2,000 square foot home typically runs $3,500 to $10,000 depending on insulation type and how many areas are being insulated. Attic-only insulation is the most common project and costs $1,500 to $4,000. Wall insulation for an existing home is significantly more expensive due to the need to open drywall or use blown-in injection methods.
What is the cheapest type of home insulation?: Fiberglass batt insulation is the least expensive option at $0.30 to $1.00 per square foot installed, not including any associated work. Blown-in fiberglass or cellulose is similarly priced and better suited to existing spaces. Spray foam is 3–8x more expensive but provides air sealing simultaneously.
Is spray foam insulation worth the extra cost?: Spray foam is worth the premium in two situations: new construction where the air-sealing benefit from the start saves energy costs for the building's lifetime, and in specific problem areas like rim joists, crawl spaces, and attic hatches where air infiltration is the dominant heat-loss mechanism. For standard attic insulation top-up, blown-in cellulose or fiberglass is almost always more cost-effective.
How long does home insulation take to pay back?: Attic insulation typically delivers an energy cost payback in 3 to 7 years — one of the best ROIs of any home improvement. The payback period depends on your current insulation R-value, local energy costs, and heating/cooling system efficiency. In cold climates with high energy costs (Northeast, Midwest), payback can be as fast as 2–3 years.
Do I need a permit to add insulation?: Adding insulation to an attic or crawl space typically does not require a permit. Spray foam insulation in enclosed wall cavities may require inspection in some jurisdictions because it's considered a structural and fire-safety concern. Check with your local building department before starting any spray foam project inside walls.