Attic Insulation Cost
Estimate attic insulation cost by square footage and type — blown-in fiberglass, cellulose, or spray foam — with old-insulation removal, every material compared, and a payback estimate based on ENERGY STAR energy-savings data.
What will it cost to insulate your attic — and is it worth it? Enter your attic size and insulation type to get the installed cost, see every material compared, and estimate how fast the energy savings pay it back.
Attic floor area
Square footage of the attic floor you're insulating — roughly your home's footprint (a single-story home's full floor area, or the area under the attic for a two-story). A 1,500 sq ft single-story home has about a 1,500 sq ft attic.
Insulation type
The biggest cost driver. Blown-in fiberglass and cellulose are the affordable, common choices; spray foam (open- or closed-cell) costs much more but air-seals as it insulates. You'll see all four compared below.
Annual heating & cooling cost
What you spend per year heating and cooling the home — roughly half of your total energy bill. Used to estimate energy savings and payback. Leave at 0 if you just want the cost.
Remove old insulation?
Tearing out and bagging old, damaged, or contaminated insulation (water damage, pests, mold) adds about $1–$2 per sq ft. Skip it if you're adding on top of sound existing insulation.
Fiberglass — Installed
$1,000–$2,500
1,000 sq ft · $1–$2.5/sq ft
Compare insulation types for your 1,000 sq ft
Cost vs. payback by type
Fiberglass and cellulose are the value picks — low cost and a reasonable payback from energy savings. Spray foam costs several times more; its premium buys air-sealing and a higher R-value per inch, not a fast energy payback, so choose it for performance or problem attics rather than ROI. Savings are largest if your attic is currently under-insulated, and air-sealing first makes any insulation work better. Check for local utility rebates (and any current tax incentives) before you start.
Cost = attic area × installed rate by type ($1–$2.50 fiberglass, $1.20–$3.20 cellulose, $1.50–$5 open-cell foam, $3–$8.50 closed-cell foam per sq ft), plus optional removal ($1–$2/sq ft). Savings estimate uses ENERGY STAR's finding that air-sealing and adding insulation saves about 15% of heating and cooling costs — applied here at 10–15% of the heating/cooling cost you entered. These are planning estimates; actual savings depend on your current insulation, climate, and home, so get local quotes and check current rebates.
💡About this calculator▼
Adding attic insulation is one of the highest-return upgrades in a home, because heat rises and a poorly insulated attic lets it pour straight out in winter (and pour in during summer). This calculator estimates what the job will cost for your attic, compares the common insulation types side by side, and — because saving energy is the whole point — estimates how quickly the energy savings pay it back.
Attic insulation is priced by the square foot of attic floor, and the material you choose is by far the biggest cost factor. Blown-in fiberglass and cellulose are the affordable, popular options; spray foam costs several times more but seals air leaks as it insulates. You enter your attic size, pick a type, and the calculator multiplies through current market rates, adds old-insulation removal if you need it, and shows the installed cost and per-square-foot figure.
For the payback, it uses the EPA/ENERGY STAR finding that air-sealing and adding insulation saves homeowners an average of about 15% on heating and cooling costs. Applied to the heating-and-cooling spending you enter, that gives a rough annual savings and a payback period — which makes the real trade-off clear: fiberglass and cellulose typically pay for themselves over time, while spray foam's premium is about performance and air-sealing, not a fast energy payback. Treat the savings as an estimate; the actual figure depends on how under-insulated your attic is now, your climate, and your home.
The calculator works in two parts: the cost to install, and the energy payback.
Cost starts from your attic floor area — the square footage you're insulating, roughly your home's footprint. It multiplies that by the installed rate for your insulation type, which is the dominant cost driver. Blown-in fiberglass is the cheapest, cellulose is a bit more, open-cell spray foam costs more again, and closed-cell spray foam is the priciest (it also delivers the highest R-value per inch). If you need to remove old insulation first — common when it's water-damaged, pest-contaminated, or moldy — that adds about $1–$2 per square foot. The result is a low–high installed range and a per-square-foot figure to check against quotes.
Payback comes from the energy savings. The EPA estimates that air-sealing and adding insulation saves an average of 15% on heating and cooling costs. The calculator applies a conservative 10–15% to the annual heating-and-cooling cost you enter (attic insulation is the biggest single piece of that whole-home figure), giving an estimated annual savings. Dividing the install cost by that savings gives a payback range in years.
That payback is where the materials really separate. Because fiberglass and cellulose cost so little per square foot, they pay back from energy savings in a reasonable number of years. Spray foam, at several times the cost, can take decades to recoup on energy savings alone — so it's chosen for air-sealing, moisture control, and tricky roof-line attics rather than for ROI. The comparison table prices all four types for your attic so you can see the difference, and you can leave the heating/cooling cost at zero if you just want the install cost.
📐How it's calculated▼
Attic insulation is priced per square foot of attic floor.
Cost: Installed cost = attic area × rate per sq ft (by type) + removal (if any)
Installed rate per sq ft (2025–2026 market ranges): Fiberglass $1.00–$2.50 · Cellulose $1.20–$3.20 · Open-cell foam $1.50–$5.00 · Closed-cell foam $3.00–$8.50 Old-insulation removal: $1–$2 per sq ft
Payback: Annual savings = 10–15% × your annual heating & cooling cost Payback (years) = installed cost ÷ annual savings
Example: A 1,000 sq ft attic, blown-in fiberglass, $1,000/yr heating & cooling, no removal →
→ Install: 1,000 × $1.00–$2.50 = about $1,000–$2,500
→ Annual savings: 10–15% × $1,000 = $100–$150/yr
→ Payback: $1,000 ÷ $150 to $2,500 ÷ $100 = roughly 7 to 25 years
The same attic in closed-cell spray foam would run about $3,000–$8,500 — far longer to pay back on energy alone, which is why foam is a performance choice, not an ROI one.
📎Sources:ENERGY STAR — Methodology for Estimated Energy Savings (15% heating/cooling, 11% total),TLS Energy Savers — Attic Insulation Cost per Square Foot (by type, removal),Green Attic — Attic Insulation Cost Comparison by Material & R-value
🔍Finding your inputs▼
Attic floor area: The square footage of the attic floor you're insulating. For a single-story home it's essentially the whole floor area; for a two-story, it's the footprint under the attic. If you don't know it, your home's square footage (per floor) is a close stand-in. A 1,000–1,500 sq ft attic is typical for an average house.
Insulation type: The biggest cost lever. Fiberglass (blown-in or batts) is the most affordable and the most common. Cellulose is blown-in recycled paper — eco-friendly, a bit denser, slightly more. Open-cell spray foam costs more but expands to air-seal as it insulates. Closed-cell spray foam is the premium option: the highest R-value per inch and a moisture barrier, but the most expensive by far. You'll see all four priced for your attic regardless of which you select.
Annual heating & cooling cost: What you spend per year to heat and cool the home — used to estimate energy savings and payback. Heating and cooling is typically about half of a home's total energy bill, so if your total energy runs ~$2,000/year, enter roughly $1,000. Don't have a number handy? Leave it at 0 and you'll still get the install cost and material comparison, just without the payback.
Remove old insulation: Choose "remove" if the existing insulation has to come out first — it's worth doing when it's water-damaged, moldy, pest-infested, or flattened and ineffective, and it adds about $1–$2 per sq ft for tear-out and bagging. If your current insulation is sound and you're just adding more on top (a common, cheaper approach), leave this off.
⚠️Special situations▼
How much insulation does my attic need — what R-value?
The U.S. Department of Energy recommends roughly R-49 to R-60 for attics in most of the country (about R-30 to R-49 in the warmest southern climates). R-value measures resistance to heat flow, and attics need the most of any part of the house because heat rises. In practice that's roughly 14–20 inches of blown-in fiberglass or cellulose. This calculator's per-square-foot rates assume bringing an attic up to a standard code R-value; if you're only topping off a partially insulated attic, your material cost will be lower since you're adding fewer inches.
Should I remove old insulation or just add more on top?
Usually you can add new insulation right over old, sound insulation — it's cheaper and works fine, as long as the existing material is dry, evenly distributed, and not compressed. You should remove the old insulation first if it's wet or water-stained, moldy, infested with rodents or pests, or so old and settled that it's lost its R-value. Removal adds about $1–$2 per square foot for the labor and disposal. If you're switching to spray foam, the old insulation typically has to come out so the foam can bond to the surfaces. When in doubt, have it inspected — adding over compromised insulation traps the problem.
Why does spray foam cost so much more, and is it worth it?
Spray foam costs several times more than blown-in fiberglass or cellulose because the material and equipment are expensive and it's a specialized install. What you get for the premium is air-sealing (the foam expands into gaps and stops air leaks that loose-fill can't), a higher R-value per inch (especially closed-cell, around R-7/inch versus ~R-3.5 for fiberglass), and, with closed-cell, a moisture barrier. It rarely pays back on energy savings alone within a reasonable timeframe, so it's the right call when you're sealing a leaky or unvented attic, insulating at the roofline, or dealing with moisture — not when you're chasing the fastest energy ROI, where blown-in wins.
Why should I air-seal the attic before adding insulation?
Insulation slows heat from conducting through the attic floor, but it doesn't stop air from leaking through gaps — around recessed lights, the attic hatch, plumbing and wiring penetrations, and the top plates of walls. If you blow insulation over those leaks without sealing them, conditioned air keeps escaping and the insulation underperforms. EPA specifically recommends air-sealing the attic first, then insulating. Air-sealing is relatively cheap (caulk and foam for small gaps, weatherstripping for the hatch) and is a big part of why the ENERGY STAR savings figure pairs 'air sealing AND adding insulation.' Budget for it as a first step.
Are there rebates or tax credits for attic insulation?
Often, yes — but they change frequently, so confirm what's active rather than assuming. Many local utilities offer rebates for adding insulation, sometimes a flat amount or a per-square-foot incentive, and you can look yours up through the ENERGY STAR Rebate Finder by ZIP code. Federal tax incentives for insulation have existed in recent years but their availability and amounts shift with legislation, so check the current rules (or ask your tax advisor) before counting on a credit. This calculator's payback is based on energy savings only and doesn't subtract rebates or credits — any incentive you qualify for shortens the payback further.
❓Common questions▼
How much does it cost to insulate an attic?
Attic insulation is priced per square foot, and the material drives the cost: installed, blown-in fiberglass runs about $1.00–$2.50 per sq ft, cellulose $1.20–$3.20, open-cell spray foam $1.50–$5, and closed-cell spray foam $3–$8.50. For a typical 1,000 sq ft attic, that's roughly $1,000–$2,500 for fiberglass up to $3,000–$8,500 for spray foam. Removing old insulation first adds about $1–$2 per sq ft. Enter your attic size and type in the calculator above for a tailored range plus a side-by-side comparison and a payback estimate.
Does attic insulation pay for itself?
Often, yes — especially the affordable blown-in types. The EPA estimates that air-sealing and adding insulation saves an average of about 15% on heating and cooling costs. Because blown-in fiberglass and cellulose cost so little per square foot, those savings typically pay back the install over a number of years; the payback is faster the more under-insulated your attic is now. Spray foam, at several times the cost, takes much longer to recoup on energy savings alone, so it's chosen for air-sealing and performance rather than ROI. The calculator estimates your specific payback from the heating/cooling cost you enter.
What is the best type of insulation for an attic?
For most attics, blown-in cellulose or fiberglass is the best value — it's affordable, fills irregular spaces well, and reaches the high R-values attics need. Spray foam (open- or closed-cell) is better when you need to air-seal a leaky attic, insulate at the roofline, or control moisture, but it costs several times more. Batts work for easy-access attics with standard joist spacing but leave gaps if not fitted carefully. The 'best' choice depends on your attic and goals; the calculator compares all four on cost so you can weigh that against the performance differences.
How much can attic insulation save on energy bills?
The EPA/ENERGY STAR estimate is that air-sealing your home and adding insulation (attic, crawl space, and basement) saves an average of about 15% on heating and cooling costs, or roughly 11% of total energy costs. Attic insulation is the single biggest contributor to that, since the attic is where the most heat is lost or gained. Your actual savings depend heavily on how under-insulated your attic is to start — a nearly bare attic can save far more, while topping off a decent layer saves less. The calculator applies a conservative 10–15% of your heating/cooling spending to estimate annual savings.
Can I add new insulation over old insulation?
Yes, in most cases you can add new insulation directly over existing insulation, as long as the old material is dry, in good condition, and not compressed — it's a common and cost-effective way to reach a higher R-value. You can add blown-in or unfaced batts over existing insulation (don't use faced batts on top, as the vapor barrier can trap moisture). You should remove the old insulation first if it's wet, moldy, pest-damaged, or you're switching to spray foam. Adding over sound insulation skips the $1–$2 per sq ft removal cost, so leave the 'remove old insulation' option off if your current layer is healthy.
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