How much does it cost to insulate a house or attic?
Insulation runs roughly $0.80–$3.50 per square foot installed for most materials — with closed-cell spray foam going higher. The biggest variable is the type: fiberglass batts are cheapest, blown-in is mid-range, and spray foam costs the most. An average attic (1,000–1,500 sq ft) runs about $1,000–$3,750 with blown-in. And because most of the bill is labor, batts and blown-in are realistic DIY savings.
Cost by insulation type
Type drives the price more than anything. Typical installed cost per square foot of area covered:
| Type | Installed / sq ft | Best for |
|---|---|---|
| Fiberglass batts | $0.80–$2.00 | Open walls, floors, standard framing |
| Blown-in (loose-fill) | $1.00–$2.50 | Attic floors, filling gaps |
| Open-cell spray foam | $1.50–$3.50 | Air-sealing walls & rim joists |
| Closed-cell spray foam | $3.00–$7.00 | Highest R per inch, moisture barrier |
Cost to insulate an attic by size
The attic is the most common — and highest-return — insulation project. Using blown-in at $1.00–$2.50 per square foot installed:
| Attic size | Installed cost |
|---|---|
| 500 sq ft | $500–$1,250 |
| 1,000 sq ft | $1,000–$2,500 |
| 1,500 sq ft | $1,500–$3,750 |
| 2,000 sq ft | $2,000–$5,000 |
Estimate the bags or rolls you need
Enter your area and coverage per bag and the insulation calculator gives the bags or rolls — and an editable cost — for your target R-value.
Open the Insulation CalculatorR-value drives the cost
Insulation is rated by R-value — its resistance to heat flow. A higher R-value means a thicker layer and more material, so it costs more. These are the common targets:
| Location | Typical R-value |
|---|---|
| Attic | R-38 to R-49 |
| 2x4 walls | R-13 to R-15 |
| 2x6 walls | R-19 to R-21 |
| Floors | R-25 to R-30 |
For blown-in insulation, the coverage per bag drops as the R-value rises — a deeper layer covers fewer square feet — so always read the bag's coverage chart for your target.
What else changes the price
- Removing old insulation. Tearing out and bagging wet, moldy, or rodent-damaged insulation adds cost before new goes in.
- Air sealing. Sealing gaps and adding baffles for ventilation is worth doing first — and adds a little to the job.
- Access. A cramped, low attic or finished walls (which may need drill-and-fill) are harder to insulate.
- Region & code. Colder climates call for higher R-values, and local labor rates move the installed price.
DIY vs. hiring a pro
Fiberglass batts and blown-in insulation are realistic DIY jobs, and the savings are real — DIY materials run only about $0.30–$1.00 per square foot, well below the installed price, because labor is a big share of any quote. Many home centers lend a blower for free with a bulk purchase of loose-fill. Spray foam is the exception: it needs specialized equipment and careful technique, and is best left to professionals. Whatever you choose, wear gloves, a mask, and goggles, and air-seal gaps before you insulate. See our methodology for how we build these ranges.