Short answer: topping up a typical 1,000 sq ft attic from about R-11 to the recommended R-49 costs roughly $1,500 to $1,850 with blown-in fiberglass, cellulose or batts, plus a few hundred dollars for air sealing. Starting from a bare attic, expect about $1.20 to $2.60 per sq ft for R-30 to R-60 with loose-fill, and three to five times more with spray foam. Most homes in the northern US need R-49 to R-60 in total.
Work out your own attic in the attic insulation cost calculator: it picks the target R-value for your climate zone and shows the inches needed.
How much insulation do you need?
ENERGY STAR recommends these total attic R-values. "Adding to 3–4 inches" applies if there is already some old insulation.
| Climate zone | Uninsulated attic | Adding to 3–4 in |
|---|---|---|
| 1: South Florida, Hawaii | R-30 | R-25 |
| 2–3: Gulf Coast, Southeast, Southern California, Southwest | R-49 | R-38 |
| 4–8: Mid-Atlantic, Midwest, Northeast, Pacific Northwest, mountains, most of Canada, Alaska | R-60 | R-49 |
To estimate what you have, measure the depth of the existing insulation and multiply by about 3 (loose fiberglass is closer to 2.5 per inch, cellulose about 3.7).
Cost by material for a 1,000 sq ft attic
Installed planning prices for 2026, starting from a bare attic floor:
| Material (R per inch) | R-30 | R-38 | R-49 | R-60 |
|---|---|---|---|---|
| Blown-in fiberglass (2.5) | $1,200 · 12 in | $1,520 · 15.2 in | $1,960 · 19.6 in | $2,400 · 24 in |
| Blown-in cellulose (3.7) | $1,297 · 8.1 in | $1,643 · 10.3 in | $2,119 · 13.2 in | $2,595 · 16.2 in |
| Fiberglass batts (3.1) | $1,452 · 9.7 in | $1,839 · 12.3 in | $2,371 · 15.8 in | $2,903 · 19.4 in |
| Open-cell spray foam (3.6) | $3,167 · 8.3 in | $4,011 · 10.6 in | $5,172 · 13.6 in | $6,333 · 16.7 in |
| Closed-cell spray foam (6.2) | $6,048 · 4.8 in | $7,661 · 6.1 in | $9,879 · 7.9 in | $12,097 · 9.7 in |
Prices scale with area: a 1,500 sq ft attic costs about 1.5 times as much. They are planning figures for professional installation; local labour rates, access and attic height move them up or down, so get two or three quotes.
Other costs to budget for
- Air sealing: sealing gaps around light fittings, pipes, flues, wiring holes and the attic hatch usually costs a few hundred dollars to over $1,000, and often saves as much as the insulation itself. Do it first; it is much harder once new insulation is down.
- Removing old insulation: roughly $1 to $2 per sq ft, needed only if it is wet, mouldy, contaminated by rodents, or in the way of air sealing.
- Vermiculite: grey-brown, pebble-like loose fill may contain asbestos. Have it tested before anyone disturbs it.
- Baffles and hatch insulation: rafter vents keep soffit ventilation open, and an insulated, weather-stripped hatch stops a big leak.
Blown-in vs batts vs spray foam
- Blown-in (fiberglass or cellulose) is the cheapest per R-value, fills around joists, wiring and awkward spaces, and is the usual choice for topping up an attic floor. Cellulose gives more R per inch and resists air movement better; fiberglass is lighter and does not settle as much.
- Batts suit DIY in open attics with standard joist spacing, but gaps around wires and pipes reduce their real-world performance.
- Spray foam both insulates and air seals, and is used on the underside of the roof deck to create a conditioned attic, for example when ducts or a furnace are up there. It costs far more and must be installed by a professional.
Is it worth it?
ENERGY STAR estimates homeowners save an average of 15% on heating and cooling costs by air sealing and adding insulation in attics, floors over crawl spaces and basement rim joists. Attic upgrades pay back fastest when there is little insulation now (under about R-19) and the home has high heating or cooling bills. If you already have R-38 or more, adding more saves little; spend the money on air sealing instead.
In the US, the federal 25C energy-efficient home improvement credit (30% of insulation materials, up to $1,200) does not apply to work completed after December 31, 2025. Check your utility and state energy office for rebates. In Canada, look for provincial and utility programmes.
Frequently asked questions
How much does it cost to blow insulation into an attic?
About $1.20 to $2.60 per sq ft for R-30 to R-60 in a bare attic with fiberglass or cellulose, or $1.50 to $1.65 per sq ft to top up R-11 to R-49.
Can I insulate my attic myself?
Many people do. Home improvement stores often lend a blowing machine with a minimum purchase of bags, which roughly halves the cost. Wear a respirator, stay on the joists and keep insulation away from recessed lights and flues unless they are rated for contact.
How many inches of insulation is R-49?
About 19.6 inches of blown fiberglass, 13.2 inches of cellulose or 15.8 inches of fiberglass batts.
Sources
- ENERGY STAR, recommended home insulation R-values and seal and insulate.
- US Department of Energy, types of insulation.
- IRS, FAQs on the 2025 changes to sections 25C and 25D.
- Installed prices: 2026 US planning ranges for professional installation, as used in our calculator.
Checked October 22, 2026.
Try the Attic Insulation Cost Calculator
How many inches of insulation you need to reach the recommended R-value, what it costs and how much heat loss it cuts.
No comments yet.