How much would it cost to insulate a 1,000 square foot attic?

The cost to insulate a 1,000 square foot attic in 2026 depends on whether you do it yourself or hire a contractor and what type of insulation you choose. For a DIY blown-in job, which is the most common and cost-effective method, materials cost about $0.60 to $1.20 per square foot to reach R38 to R49 from scratch or to top up existing insulation. That means $600 to $1,200 for 1,000 square feet when you use the free blower machine rental offered by Home Depot and Lowe's with purchase of 10 or more bags of GreenFiber cellulose or Johns Manville Climate Pro fiberglass. Each bag costs $35 to $55 and covers about 30 to 60 square feet at R38 depending on brand. If you hire a professional insulation contractor, the cost for 1,000 square feet of blown-in attic insulation typically ranges from $1.50 to $3.00 per square foot, or $1,500 to $3,000 total, including air sealing of top plates and penetrations, which is highly recommended. For fiberglass batts, materials cost $1.00 to $1.70 per square foot installed DIY. Spray foam is much more expensive. Open-cell spray foam for 1,000 square feet costs $3.50 to $5.50 per square foot or $3,500 to $5,500, while closed-cell costs $5.50 to $8.50 per square foot or $5,500 to $8,500. Many utilities offer $200 to $600 rebates and federal tax credits can offset 10 to 30 percent.