Attic Insulation Cost (2026)
By Your Name · Last updated · How we calculate
Attic insulation costs $1 to $4 per square foot installed, and $1,000 to $2,700 for a typical attic (HomeGuide). Blowing loose fill over existing insulation on the attic floor is the cheapest option. Removing the old insulation first adds $1–$2 per square foot. Spraying foam under the roof deck to make an unvented attic costs roughly two times as much as topping up the floor with open-cell foam, and up to six times as much with closed-cell.
Key takeaways
- Topping up the attic floor with blown-in is the best value for most homes.
- Replacing (removal + new) adds about $2,617 on a 1,500 sq ft attic. Only do it if the old insulation is wet, moldy or contaminated.
- Spray foam on the roof deck makes sense mainly when ducts or the furnace are in the attic.
- Air sealing ($350–$3,000) belongs in every quote; ask if it’s included.
Run your own numbers: Attic Insulation Cost Calculator · Blown-In Insulation Calculator
The attic is usually the cheapest and most effective place to add insulation, but “attic insulation” covers very different jobs, from a DIY top-up costing a few hundred dollars in bags to a five-figure roof-deck spray foam job. This guide breaks down the options with real numbers. For your own attic, the attic insulation cost calculator works out bags, DIY and contractor prices.
Attic insulation cost at a glance
| Cost | |
|---|---|
| Per square foot, installed | $1–$4 |
| Typical attic (national average $1,800) | $1,000–$2,700 |
| Small attic | from $500 |
| Large attic | up to $6,000 |
| Replacing (removal + new) | $2–$6 per sq ft |
| Labor only | $0.50–$1.30 per sq ft |
HomeGuide, January 2026. Some insulation companies have a $1,500–$2,000 minimum.
Attic insulation cost by type
| Type | Installed per sq ft | Best for |
|---|---|---|
| Blown-in fiberglass or cellulose | $0.90–$2.40 | Topping up existing attics; irregular joists and obstructions |
| Batts and rolls | $0.80–$2.60 | Open, regular joists; new or fully cleared attics |
| Spray foam, attic floor | $1.00–$4.50 | Air sealing hard-to-reach areas |
| Spray foam, roof deck | $1.50–$5.00+ | Unvented attics with ducts or HVAC equipment |
| Reflective / radiant barrier | $0.50–$2.20 | Hot climates, alongside regular insulation |
HomeGuide price ranges. Roof-deck spray foam is priced per square foot of roof, which is larger than the attic floor.
Three ways to insulate the same attic
A 1,500 sq ft attic in climate zone 5 with 3½" of old batts, a 6/12 roof (about 1,677 sq ft of roof deck) and 24" trusses. The target is ENERGY STAR’s R-60 on the floor, or about R-27 to R-49 at the roof deck. The floor jobs include air sealing and 30 baffles.
| Approach | Contractor (average) | Range |
|---|---|---|
| 1. Air seal, then blow cellulose over the old batts to R-60 | $4,841 | $2,639–$7,438 |
| 2. Remove old batts, air seal, blow new cellulose to R-60 | $7,458 | $4,451–$10,944 |
| 3a. Open-cell foam on the roof deck, 7¼" (R-27) | $6,839 | $4,559–$11,399 |
| 3b. Closed-cell foam on the roof deck, R-49 (7.5") | $18,964 | $11,852–$34,371 |
Option 1 gets the house to the recommended level for the least money. Option 2 is only worth paying for if the old insulation is damaged. Option 3 changes how the house works: the attic becomes semi-conditioned, so ducts and the furnace up there stop losing heat to a cold attic. It costs far more, and the roof deck foam guide has the details: open-cell spray foam cost. Gable ends, vent sealing and any required coatings are extra.
Attic insulation cost by size
Topping up 3½" of old batts to R-60 (zones 4–8), contractor prices at average rates:
| Attic floor | Cellulose | Fiberglass | DIY cellulose |
|---|---|---|---|
| 600 sq ft | $1,243 $2.07/sq ft | $1,452 $2.42/sq ft | $773 44 bags |
| 1,000 sq ft | $2,066 $2.07/sq ft | $2,439 $2.44/sq ft | $1,236 73 bags |
| 1,500 sq ft | $3,091 $2.06/sq ft | $3,630 $2.42/sq ft | $1,811 109 bags |
| 2,000 sq ft | $4,132 $2.07/sq ft | $4,878 $2.44/sq ft | $2,402 146 bags |
Our contractor figures price material at retail bag prices, so they lean high; HomeGuide’s survey average for a whole attic is $1,800. Use them as a budget ceiling.
Removal, air sealing and other extras
- Removing old insulation: $1.00–$2.00 per sq ft. It’s needed when insulation is wet, moldy, contaminated by rodents, or smoke-damaged.
- Air sealing: $350–$3,000, depending on how many penetrations, ducts and fixtures there are.
- Baffles: $2.00–$3.00 each, one per rafter bay at vented eaves.
- Venting exhaust fans outside: HomeGuide puts roof vent installation at $200–$700. Bath fans must not dump moist air into the attic.
- Cleanup and hazards: attic cleaning $100–$500+, pest inspection $40–$150, asbestos testing $250–$850 if there’s vermiculite, and mold remediation if needed.
DIY vs. hiring a contractor
Blowing insulation over the attic floor is one of the more doable DIY insulation jobs. You’re paying for bags, a free or cheap blower, and a day with a helper. For a 1,000 sq ft attic, DIY costs about $1,236, against roughly$2,066 for a contractor in our estimate. Hire out:
- Removal of old insulation (big vacuum trucks make it quick for a crew)
- Low-slope attics where you can’t reach the eaves
- Spray foam of any kind beyond small touch-ups
- Anything with vermiculite, mold or knob-and-tube wiring
Is attic insulation worth it?
HomeGuide estimates adding attic insulation saves 10–20% on heating and cooling, depending on the climate and what you start with. The less insulation you have now, the bigger the gain: going from R-11 to R-60 matters far more than going from R-38 to R-60. Pair it with air sealing for the best result, and check for utility rebates before you hire. Many utilities pay part of the cost.
Frequently asked questions
How much does it cost to insulate a 1,000 sq ft attic?
HomeGuide’s range is $1,000–$4,000 installed. Topping up existing insulation with blown-in sits at the low end; removal plus new insulation, or spray foam, at the high end.
Is it cheaper to add insulation or replace it?
Adding is cheaper. Removal costs $1.00–$2.00 per sq ft on top of the new insulation, and dry, clean old insulation still counts toward your R-value.
How long does attic insulation last?
Kept dry and undisturbed, fiberglass lasts for decades. Cellulose can lose performance if it gets wet. HomeGuide suggests checking the depth after 15–20 years.
Do I need to remove old insulation before adding new?
No, unless it’s wet, moldy, pest-contaminated or vermiculite. New loose fill can go right on top, but use unfaced material, not faced batts.
How much insulation should my attic have?
R-49 to R-60 for most of the U.S. See how much attic insulation you need for your zone and the depth in inches.
Sources
- HomeGuide — Attic insulation cost (Jan 2026)
- HomeGuide — Blown-in insulation cost (Nov 2025)
- ENERGY STAR — Recommended home insulation R-values
- Home Depot — Owens Corning AttiCat 27.5 lb bag (Oct 2026)
- Home Depot — Greenfiber Sanctuary 25 lb bag (Oct 2026)
- ArmorThane — Spray foam insulation cost (Sep 2026)
- Modernize — Spray foam insulation (Aug 2026)