Attic insulation costs $1,500–$3,500 for a typical US home, depending on the insulation type, R-value target, and attic size. Blown-in cellulose or fiberglass is the most cost-effective option at $1–$2 per square foot installed, while spray foam runs $3–$7 per square foot. The Department of Energy estimates that proper attic insulation can reduce heating and cooling costs by 10–50%.
Average attic insulation costs by type[1,2,3]
| Insulation type | Cost per sq ft (USD) | Best for |
|---|---|---|
| Blown-in fiberglass | $1.00–$1.50 | Open attics, topping up existing |
| Blown-in cellulose | $1.00–$1.80 | Open attics, eco-friendly option |
| Fiberglass batts | $0.80–$1.50 | New construction, accessible joists |
| Open-cell spray foam | $1.50–$3.00 | Cathedral ceilings, air sealing |
| Closed-cell spray foam | $3.00–$7.00 | Moisture barrier, structural strength |
| Mineral wool batts | $1.50–$3.00 | Fire resistance, soundproofing |
Attic insulation costs in the United States
For a 1,200 sq ft attic, blown-in insulation to R-49 costs $1,500–$2,500 installed. Spray foam for the same space runs $4,000–$8,500. Many utility companies offer rebates of $200–$1,000 for insulation upgrades, and the federal Inflation Reduction Act provides a 30% tax credit (up to $1,200/year) for insulation improvements through 2032.
The DOE recommends R-38 for mild climates (zones 1–3) and R-60 for cold climates (zones 5–8). DIY blown-in insulation is feasible — big-box stores loan blower machines with a minimum purchase of insulation material ($500–$800 for a typical attic).
What affects the cost?
- Insulation type — blown-in is cheapest; spray foam costs 3–5x more but provides air sealing
- R-value target — the DOE recommends R-38 to R-60 for attics depending on climate zone
- Attic accessibility — tight spaces, low clearance, and obstacles increase labor time
- Existing insulation — removal of old, damaged, or contaminated insulation adds $1–$2/sq ft
- Air sealing — sealing gaps around wires, pipes, and fixtures before insulating adds $500–$1,500
- Attic size — typical US attic is 1,000–1,500 sq ft
How to save on attic insulation
- Claim available rebates — utility rebates, federal tax credits, and state programs can cover 30–50% of costs
- Start with air sealing — sealing gaps before adding insulation maximizes energy savings
- Choose blown-in for open attics — it's the most cost-effective option for standard attics
- Top up existing insulation — adding blown-in over old batts is cheaper than full removal and replacement
- DIY blown-in — renting a blower and buying material can cut costs by 50% for accessible attics