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Blown-In Insulation Cost per Sq Ft (2026): Cellulose vs Fiberglass by R-Value
Blown-in insulation costs $1.50 to $3.50 per sq ft installed in 2026 ($0.90 to $1.80 DIY). Cellulose vs fiberglass by R-value, attic vs walls, bags needed.
If you are pricing blown-in insulation cost per sq ft, here is the short answer: a professional install runs $1.50 to $3.50 per square foot in an open attic, with a national average around $2.00. Doing it yourself with rented equipment drops that to roughly $0.90 to $1.80 per square foot, mostly the cost of the bags. Closed walls cost more.
That range covers most homes, but the real number depends on three things: the material (fiberglass vs cellulose), the R-value you are targeting (depth), and where it goes. An open attic floor is cheap; dense-packing a finished wall is not. This guide breaks down each, with current 2026 numbers, a coverage chart, and the prep costs that other pages tend to bury.
$1.50–$3.50
Installed cost per sq ft
Open attic, pro install, 2026
$0.90–$1.80
DIY cost per sq ft
Bags plus a usually-free blower rental
26–32 bags
Per 1,000 sq ft at R-49 to R-60
Fiberglass or cellulose loose-fill
$1,200/yr
Max 25C tax credit
30% of insulation + air-sealing materials
Before you collect quotes, it helps to know what the upgrade is actually worth in your house. Plug your attic size, current R-value, and heating fuel into the Insulation ROI tool. It estimates annual savings and a rough payback so you can tell whether R-60 is worth the extra bags or whether R-49 is plenty. Use it after this guide gives you the cost side.
On this page
- Blown-in insulation cost per sq ft: the core numbers
- Cost by material: cellulose vs fiberglass vs mineral wool
- Cost by attic size: what you will actually pay
- How depth and R-value change the price
- DIY vs pro: where the savings really are
- Walls vs attic: dense-pack is a different job
- Prep and add-on costs the headline number hides
- Tax credits and rebates in 2026
- When blown-in is NOT the right spend
- Red flags in a blown-in quote
- Frequently asked questions
- Next steps
Blown-in insulation cost per sq ft: the core numbers
Loose-fill (the industry term for blown-in) is priced two ways, and confusing them is where most homeowners get a sticker shock. There is the material-only cost per square foot, and the installed cost that includes a crew, equipment, and prep.
Here is the 2026 picture, drawn from Modernize, Angi, and home-center pricing:
| Cost line | Per sq ft | Notes |
|---|---|---|
| Material only (any loose-fill) | $0.50 – $1.50 | What you pay for bags at the store |
| Pro labor | $1.00 – $2.00 | Crew, blower, setup, cleanup |
| Installed, open attic | $1.50 – $3.50 | National average ~$2.00 |
| Installed, closed walls (dense-pack) | $1.70 – $3.70 | Drilling, packing, patching |
| DIY (material + free/cheap blower) | $0.90 – $1.80 | You supply the labor |
Why one quote says $7/sq ft and another says $1.50
Some cost databases (Homewyse, for example) list installed attic insulation as high as $3.75 to $7.77 per square foot. That is not a different planet; it usually bundles heavy air sealing, baffles, old-insulation removal, and a small, hard-access attic where the crew spends more time setting up than blowing. A clean, walk-in 1,500 sq ft attic with no tear-out lands near the low end. When you compare bids, compare the scope, not just the per-foot number.
Cost by material: cellulose vs fiberglass vs mineral wool
The material you choose moves the price and changes how thick the layer has to be. The higher the R-value per inch, the less depth (and fewer bags) you need to hit a target.
| Material | R-value per inch | Material cost/sq ft | Best for |
|---|---|---|---|
| Fiberglass loose-fill | 2.5 – 3.5 | $0.50 – $1.10 | Open attics, budget jobs, lightest weight |
| Cellulose (blown) | 3.2 – 3.7 | $0.60 – $1.80 | Better air resistance, recycled content |
| Dense-pack cellulose | 3.2 – 3.7 | $2.00 – $2.30 | Closed walls, sound control |
| Mineral wool (rock wool) | 3.0 – 3.7 | $1.40 – $2.10 | Fire resistance, sound, premium attics |
A useful way to think about it: on a per-R-value-per-square-foot basis, fiberglass and cellulose end up close, because cellulose costs a bit more per bag but you need fewer bags to reach the same R. Mineral wool is the premium pick and rarely the budget choice. For most attics, the real decision is fiberglass vs cellulose, and it comes down to air-movement performance and your contractor's preference more than dollars.
Installed cost per square foot by scenario (2026)
you supply the labor
most common
drill + patch
heavy air seal + removal
Cost by attic size: what you will actually pay
Per-square-foot pricing is for comparison. What you write the check for is the total. These are installed-cost ranges to bring an attic to roughly R-49, the common target in much of the country:
| Attic floor area | Installed cost (to ~R-49) | Rough DIY material cost |
|---|---|---|
| 500 sq ft | $750 – $1,750 | $450 – $900 |
| 1,000 sq ft | $1,500 – $3,000 | $900 – $1,700 |
| 1,500 sq ft | $1,800 – $3,800 | $1,200 – $2,300 |
| 2,000 sq ft | $2,500 – $4,500 | $1,500 – $3,000 |
| 2,500 sq ft | $3,000 – $5,250 | $2,000 – $3,800 |
Assuming a clean attic with adequate access, light air sealing, and no old insulation to remove. Add the prep costs below if any of those do not apply.
Reddit reality check
A homeowner with a 500 sq ft attic was quoted $2,300 for blown cellulose and balked at "$4.60 per square foot." That math is correct but the framing is off: small jobs carry fixed costs (mobilization, setup, minimum charge), so the per-foot number always looks high on a tiny attic. The same crew on a 1,500 sq ft attic would quote far less per foot. Judge small jobs on the total and the scope, not the per-square-foot rate.
How depth and R-value change the price
Loose-fill is sold by coverage at a target depth, so your R-value goal directly sets how many bags get blown in. More R means more depth, more bags, and more money. This coverage chart (per 1,000 sq ft) is the one most contractors work from:
| Target R-value | Bags per 1,000 sq ft | Approx. material price |
|---|---|---|
| R-13 to R-21 | 7 – 10 | $230 – $330 |
| R-30 to R-49 | 15 – 20 | $500 – $1,600 |
| R-38 to R-49 | 20 – 26 | $1,300 – $1,600 |
| R-49 to R-60 | 26 – 32 | $1,600 – $2,000 |
How much R you actually need depends on climate. The U.S. Department of Energy's recommended attic levels run about R-30 to R-49 in the warm South, R-38 to R-60 in moderate zones, and R-49 to R-60 in cold northern climates. Most under-insulated attics today are taken to R-49 or R-60. Going past your zone's top number is mostly wasted money; the savings curve flattens out. That is exactly the trade-off the Insulation ROI tool helps you test, and it's the same payback logic in our attic insulation ROI guide.
DIY vs pro: where the savings really are
The labor line ($1 to $2 per square foot) is the part DIY removes. The equipment is not the barrier most people expect: major home centers lend a blower machine free when you buy a minimum number of bags (often 10 to 20), and a bag of fiberglass loose-fill like AttiCat runs around $40 to $45. That is why a DIY attic can land near $0.90 to $1.80 per square foot all in.
DIY makes sense when:
- The attic is a clean, walk-in space with decent headroom.
- You are simply adding depth over existing insulation, not removing it.
- There is no knob-and-tube wiring, moisture, or pest mess.
- You have a helper to feed bags while you run the hose (it is a two-person job).
Hire a pro when:
- You are dense-packing walls, which needs the right machine, pressure, and patching skill.
- The job needs serious air sealing or old insulation removal first.
- Access is tight, headroom is low, or there are ducts and obstructions everywhere.
- You suspect asbestos (old vermiculite) or knob-and-tube wiring. Stop and get a pro.
I have watched both sides of this. On a 1990s Denver attic I walked, the crew spent nearly two hours air sealing top plates, the bathroom fan housing, and a wiring chase before a single bag of cellulose went in, and that prep is exactly why the homeowner stopped feeling a cold draft over the hallway. On a DIY job in a 1970s ranch, the homeowner rented the free AttiCat blower, blew R-38 over the existing R-19, and finished a 1,100 sq ft attic in an afternoon for about $1,300 in bags, less than half a pro quote. The difference was scope: the DIY attic needed nothing but more depth.
Walls vs attic: dense-pack is a different job
Blowing an open attic floor is gravity-friendly: the material just piles up to depth. Closed walls are the opposite. To insulate a finished wall, the crew drills a row of access holes, blows material to a packed density (around 3.5 lb per cubic foot for dense-pack cellulose) so it will not settle and slump, then plugs and patches every hole. That extra labor is why walls run $1.70 to $3.70 per square foot of wall versus the cheaper attic number.
Dense-pack also does double duty as an air-leakage control layer inside the cavity, which is why older homes with drafty walls often get it. It is almost never a DIY project; under-packing leaves voids that settle into cold stripes a year later.
Prep and add-on costs the headline number hides
The per-square-foot quote is for the insulation. These line items are common and they are where budgets blow up:
| Add-on | Typical cost | When it applies |
|---|---|---|
| Air sealing | $300 – $1,500 | Almost always recommended; the comfort lever |
| Old insulation removal | $1.50 – $3.00 / sq ft | Wet, contaminated, or matted material |
| Ventilation baffles | $2 – $5 each | To keep soffit vents from getting buried |
| Mold remediation | $10 – $25 / sq ft | Moisture-damaged areas |
| Pest cleanup | $50 – $500 | Droppings, nests, contamination |
| Asbestos abatement | $1,200 – $3,300 | Old vermiculite; specialist only |
Air sealing deserves a callout. Insulation slows conductive heat flow, but it does not stop air from leaking through gaps around can lights, the attic hatch, plumbing stacks, and top plates. Spend on the sealing and you feel it; skip it and the new R-value underperforms. For a deeper breakdown of attic-specific pricing and removal, see our attic insulation cost guide and attic insulation removal cost guide.
The most common mistake
The number-one regret I hear is "we added insulation and it still drafts." Nine times out of ten that is unsealed air leakage, not too little R-value. Insist that air sealing is written into the scope, or do it yourself first. Burying soffit vents (which chokes attic ventilation and invites moisture) is a close second.
Tax credits and rebates in 2026
Insulation is one of the few home upgrades with a live federal credit. The 25C Energy Efficient Home Improvement Credit covers 30% of the material cost of insulation and air sealing, capped at $1,200 per year, as the law is currently written for 2025 and into 2026. Two things to know:
- Labor does not count for insulation and air sealing. Only the material qualifies. That actually nudges DIY jobs toward the better credit ratio, since your cost is mostly material.
- The product must meet the criteria the IRS references (generally IECC/ENERGY STAR levels). Keep receipts and the manufacturer's compliance statement.
A separate note for 2026: the residential 25D clean-energy credit (the one for solar and batteries) ended December 31, 2025. That is a different program; it does not affect the 25C insulation credit. Confirm the current rules on the IRS Energy Efficient Home Improvement Credit page before you file, and check your utility, because many run their own rebates on attic insulation and air sealing that stack with the federal credit. The insulation upgrade hub is a good next stop for pairing insulation with other improvements.
When blown-in is NOT the right spend
Be willing to skip it or fix something else first. Blown-in is a poor use of money when:
- Your attic already meets the recommended R-value. Topping a healthy R-49 up to R-60 saves little. Run it through the ROI tool before you buy more bags.
- You have a moisture or roof-leak problem. Wet insulation loses R-value and grows mold. Fix the water first, always.
- The real problem is air leaks or ducts. If leaky attic ductwork or a giant unsealed hatch is the comfort issue, more insulation just blankets the symptom.
- You are dealing with vermiculite that may contain asbestos. Do not disturb it. Get it tested and abated by a specialist.
- The cavity needs an air or vapor strategy you cannot meet. Some closed assemblies want spray foam instead; compare in our spray foam insulation cost per sq ft guide.
Red flags in a blown-in quote
- No air-sealing line item, or a vague "we'll seal as needed" with no scope.
- No target R-value or depth-marker/coverage-verification plan.
- A per-square-foot price with no mention of removal when your attic clearly has old, matted insulation.
- Pressure to "buy more R" without any payback reasoning.
- A wall dense-pack quote that does not mention packed density or patching.
- For walls, a price that matches an open-attic rate (dense-pack is more work and should cost more).
Frequently asked questions
How much does blown-in insulation cost per square foot in 2026? Professionally installed, $1.50 to $3.50 per square foot for an open attic (national average ~$2.00). Material alone is $0.50 to $1.50; pro labor adds $1.00 to $2.00. Dense-packing closed walls runs $1.70 to $3.70.
Is cellulose or fiberglass cheaper? Fiberglass material is cheapest at about $0.50 to $1.10 per square foot; cellulose runs $0.60 to $1.80. But cellulose packs more R per inch (3.2–3.7 vs 2.5–3.5), so on a per-R basis they are close. Choose on air-movement performance and contractor skill, not the bag price.
How much to insulate a 1,000 sq ft attic? Roughly $1,500 to $3,000 installed to reach R-49, or $900 to $1,700 if you DIY. Removing old insulation or heavy air sealing pushes it higher.
How many bags per 1,000 sq ft? For R-49 to R-60, about 26 to 32 bags. R-30 to R-49 is 15 to 20; R-13 to R-21 is 7 to 10. Always check the specific bag's coverage chart.
Does it qualify for a tax credit? Yes. The 25C credit covers 30% of insulation and air-sealing material cost, up to $1,200 per year. Labor does not count for insulation. Confirm current IRS rules before filing.
What R-value should the attic be? DOE recommends about R-30 to R-49 (South), R-38 to R-60 (moderate), and R-49 to R-60 (cold). Most upgrades target R-49 to R-60.
Next steps
- Size the job and the payback. Drop your attic size, current depth, and heating fuel into the Insulation ROI tool to see whether R-49 or R-60 is the smarter spend.
- Get 2 to 3 scoped quotes that name a target R-value, list air sealing, and call out any removal, so you compare scope, not just a per-foot rate.
- Plan it alongside your other upgrades at the insulation hub, and compare related projects in our attic insulation cost and spray foam cost guides.
Sources & further reading
- Insulation (Energy Saver): R-value guidance by climate zone — U.S. Department of Energy
- Energy Efficient Home Improvement Credit (Section 25C) — IRS
- 2026 Blown-In Insulation Cost Guide — Modernize
- How Much Does Blown-In Insulation Cost? [2026 Data] — Angi
- ENERGY STAR: Seal and Insulate Your Home — ENERGY STAR
Frequently asked questions
How much does blown-in insulation cost per square foot in 2026?+
Professionally installed blown-in insulation runs $1.50 to $3.50 per square foot for an open attic, with a national average near $2.00. Material alone is $0.50 to $1.50 per square foot, and pro labor adds about $1.00 to $2.00. Dense-packing closed walls costs more, roughly $1.70 to $3.70 per square foot, because of drilling and patching.
Is cellulose or fiberglass blown-in insulation cheaper?+
Fiberglass loose-fill is usually the cheapest material at about $0.50 to $1.10 per square foot, while blown cellulose runs $0.60 to $1.80. Cellulose has a higher R-value per inch (about 3.2 to 3.7 vs 2.5 to 3.5 for fiberglass), so it can hit a target R-value in a thinner layer. On a per-R-value basis the two are close; pick based on air-movement performance and contractor skill, not just the bag price.
How much does it cost to blow insulation into a 1,000 sq ft attic?+
Expect roughly $1,500 to $3,000 installed to bring a 1,000 sq ft attic up to R-49, or about $900 to $1,700 if you DIY with rented equipment. The spread depends on existing depth, air-sealing scope, and access. Adding to thin existing insulation costs less than a tear-out-and-replace job.
How many bags of blown insulation do I need per 1,000 sq ft?+
For R-49 to R-60 in an attic, plan on about 26 to 32 bags per 1,000 sq ft of fiberglass or cellulose. Lower targets need fewer: R-30 to R-49 is roughly 15 to 20 bags, and R-13 to R-21 is about 7 to 10. Always read the coverage chart on the specific bag, since coverage per bag varies by brand and target depth.
Is DIY blown-in insulation worth it versus hiring a pro?+
DIY can cut your cost to about $0.90 to $1.80 per square foot since many home centers lend the blower free with a minimum bag purchase. It works best in a clean, walk-in attic. Hire a pro when you need wall dense-packing, careful air sealing, old-insulation removal, or work around knob-and-tube wiring, where mistakes get expensive.
How much does it cost to blow insulation into existing walls?+
Dense-packing closed wall cavities costs about $1.70 to $3.70 per square foot of wall, more than an attic, because the crew drills access holes, blows to a packed density near 3.5 lb per cubic foot, then plugs and patches. Dense-pack cellulose material alone runs roughly $2.00 to $2.30 per square foot. It is rarely a DIY job.
Does blown-in insulation qualify for a tax credit in 2026?+
Yes. The federal 25C Energy Efficient Home Improvement Credit covers 30% of insulation and air-sealing material costs, up to $1,200 per year, through 2025 and into 2026 as currently written. Labor does not count for insulation, and the product must meet IRS-referenced criteria. Confirm current rules with the IRS before you file.
What R-value should blown-in attic insulation be?+
The U.S. Department of Energy recommends about R-30 to R-49 for southern attics, R-38 to R-60 for moderate climates, and R-49 to R-60 for cold northern climates. Most uninsulated or under-insulated attics target R-49 to R-60 today. Going above your zone's range adds cost with little extra savings.
Why is air sealing recommended before blowing in insulation?+
Insulation slows heat flow but does not stop air leaks, and a leaky ceiling lets warm air bypass even a deep layer. Air sealing the attic plane costs about $300 to $1,500 and is usually the part you actually feel. Skipping it is the most common reason a freshly insulated attic still feels drafty.
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