Batt insulation cost, per bag and per square foot

The unit that matters is dollars per square foot of ceiling at a stated R-value. A bag price on its own tells you nothing, because two bags at the same rating do not cover the same area. Divide the bag by its published coverage and the products line up.

Figures: material only, at retail shelf price. Each row is the package price divided by the coverage the listing publishes at that R-value. Read at The Home Depot on 2026-08-11 and quoted, never averaged. No labor, no delivery, no disposal, no air sealing. A contractor buys below shelf price, and that discount is not measured here, so nothing is discounted.

Look at the first two rows. Same material, same rating, same store, same day. One works out to $1.67 a square foot and the other to $1.36. That is $0.30 a square foot, about 18 percent, on a choice nothing on the shelf label explains. On a 1,000 square foot attic the gap is about $302 of material. It is also the reason this page will not give you an average: an average of two products hides the one comparison worth making, which is the one you make in the aisle with a calculator.

The second thing worth noticing is the R-38 row. It costs more per bag and covers more floor, so per square foot it lands within a cent of the R-30 bag. Batt material barely moves between those two ratings. Loose fill does not behave that way, which is the next section.

Every number above carries a limit, and the limits belong beside the number rather than in a footnote.

This is the question the page exists to answer, so here is the answer with the numbers under it. On an attic floor you can blow, batts are the expensive way to a given R-value.

Figures: material only, at retail shelf price, 2026-08-11 for the batt, stone wool and cellulose rows and 2026-08-07 for the blown fiberglass anchor. Blown fiberglass at R-30 is a published coverage point. Its R-38 figure is worked out between published points, and the cellulose range is the maker's own two columns, one adjusted for framing and one not.

The verdict, in one line. At R-30 the batt costs about 69 percent more than blown fiberglass and roughly 2.7 to 2.9 times what cellulose costs, for the same rating on the same ceiling.

There is a second finding here that most cost pages miss. The gap closes as the target rises. At R-38 the batt is only about 31 percent over blown fiberglass. Loose fill packs down under its own weight, so each bag covers less floor the deeper you go, while a batt covers what the bag says at any rating. The blown-in cost page works that settling effect through in full, and blown-in against batts compares the two on everything except money.

One limit worth stating. Above R-38 no single batt in this data reaches the target, so a deeper attic means two layers, and this site carries no priced second layer. If you need R-49 or R-60, price the loose fill first. How much R-value do I need sets the target before you price anything.

No installed batt price is published on this site, and that is a deliberate gap. The model here times a crew blowing loose fill through a hose. Batt work is a different job: a person in the attic, cutting to fit, bay by bay. Nobody here has measured how long that takes, so pairing the batt material figure with the blowing labor figure would invent a number, and this page will not.

What the model does carry is the labor half, and it is worth having, because that half is driven by attic floor area rather than by which material you chose. It runs $0.47 to $0.95 a square foot, or $474 to $948 on a 1,000 square foot attic. Two of the three inputs behind it are estimates rather than measurements.

The wage in there is measured: the Bureau of Labor Statistics Occupational Employment and Wage Statistics, May 2025, gives $26.32 an hour as the national mean for insulation workers in floors, ceilings and walls. The crew hours and the multiplier on the wage are the estimated parts. The cost index ranks the same wage by state, and the installation cost page takes apart what the multiplier buys.

What to ask a contractor for instead

Ask each contractor to split the bid. Material on one line, labor on the other, with the floor area, the target R-value, and the product and rating of the batt written down. Then check the material line against $1.67 a square foot at R-30. A quote that will not separate the two cannot be judged against anything.

Three lines decide whether two bids are even quoting the same job: air sealing, baffles at the eaves, and removal of what is up there now. Get a yes or no on each. Air sealing is the one most often left out and the one most often worth doing first.

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Batts are usually bought for a reason that is not price, and the reasons are good ones. Find your attic in the first column.

The machine row deserves its own line, because it is the one that surprises people. Blowing is cheap per square foot partly because the machine comes free with enough bags. The Home Depot words the term this way: "Free 24 hour blower machine rental with the purchase of 10 bags." Lowe's words it this way: "Free 24-Hour machine rental with purchase of 10 bags or more AttiCat." Both were read 2026-08-11. Neither retailer publishes a daily rate on the rental listing, so the cost of the machine on a job that clears ten bags is nothing. A deposit and a card hold are normal at the counter and are not published either. Ten bags of the blown anchor covers about 685 square feet at R-30. Below that, the terms do not apply and batts stop looking expensive.

Doing it yourself? The gear page lists what the job needs, by job rather than by product, and says on the page that nothing was tested. A fitted respirator and sealed eye protection are not optional in a hot attic full of loose fiber. The install guide covers the order of work.

A labeled R-value describes a batt at full thickness, filling its bay edge to edge, with nothing bearing on it. That is how the number is measured in a laboratory under the FTC R-value Rule (16 CFR Part 460), using test methods such as ASTM C518. An attic floor is the assembly least likely to hand a batt any of those conditions.

Read it as money. At $1.67 a square foot, you are paying for R-value the ceiling only gets if the batt fits. A tenth of a 1,000 square foot attic is $168.76 of material. Squash a batt under stored boxes, leave a finger gap at the end of a bay, or cut one short around a wire, and part of that is spent on nothing. No derating figure is published here, because no measured one exists in this site's reference data and the size of the loss depends on the install.

Two checks before you buy, both arithmetic you can do at the hatch.

• Bay width. The clear bay at 16 inch centers is 14.5 inches, and the batt made to grip it is 15 inches wide. At 24 inch centers it is 22.5 and 23 inches. Those come from the 1.5 inch dressed thickness of nominal 2x framing under the American Softwood Lumber Standard PS 20. The R-30 listing states a width of 16 inches and does not state the spacing it suits, so measure ten or twelve bays before buying anything.
• Batt thickness against joist depth. The R-30 batt is 9.5 inches thick and the R-38 batt is 12 inches. A 2x10 joist is 9.25 inches deep and a 2x8 is 7.25. So both batts stand proud of the framing in most attics, which is fine until something is laid on top of them.

This is also why the R per inch of 2.9 to 3.8 for glass fiber batts flatters them on paper. The number is real and it is measured at full loft. The fiberglass batts page owns that argument in full, including what happens at the ends of bays.

Both products priced on this page are unfaced. That is not an accident of the shelf. A facing is a kraft paper or foil vapor retarder with stapling flanges, and it belongs against the side that is warm in winter, which for a ceiling means face down against the drywall.

One vapor retarder per assembly is the rule that follows. Lay a faced batt over insulation that already has a facing under it and you have built a sandwich with a retarder on both sides. Moisture that gets in has nowhere to dry to. The fiberglass batts page works through that in full, and adding over existing insulation covers the layer question.

The cost of getting it wrong is bigger than the price gap between the two bags. A faced bag bought for a job that needed unfaced ends one of three ways. A return trip, which costs a day. A slow pass slashing the facing on every batt, which costs hours. Or a layer left as it is, which can end up wet, and wet material gets bought twice, once now and once when it comes out.

At $1.67 a square foot on a 1,000 square foot attic, that last one puts $1,687.58 of material at risk. Whether a ceiling wants a vapor retarder at all depends on your climate zone. Energy codes cover new building and work done under a permit. They do not usually cover adding insulation to an attic you already have. Which edition applies where you live depends on your state, and often on your city. Your local building department is the only authority on it.

Batts make one part of this easy. A bag of loose fill covers less floor as the target rises, so its coverage has to be read off a chart at your R-value. A bag of batts covers what it says, at the rating printed on it, with no settling correction to make.

On a 1,000 square foot attic that gives round numbers. At R-30 the job is 19 whole bags at 53.33 square feet each, or $1,687.58 of material. At R-38 it is 16 bags at 64 square feet, or $1,715.36. Bags are sold whole, so round up. Measure the attic floor rather than the house footprint, and take the target from the R-value guide or run your own numbers in the calculator.

Two habits that protect the money. Buy from one lot where you can, because coverage and thickness are stated per product and not per material. And keep the bag until the job is done, because the label is the only place the rating and the dimensions appear, and it beats any table on any website, including this one.

We do not sell insulation and we do not install it, which is why this section exists. For most attic floors, batts are the more expensive way to the same R-value, and the reason to buy them is access rather than money. Four cases where the answer is to spend less, or nothing.

• You are buying batts to save money on an open floor. That reason does not hold up. At R-30 the material is $1.67 a square foot against $0.99 for blown fiberglass and $0.58 to $0.62 for cellulose. If the attic is open and you can get bags through the hatch, blow it.
• You are already within about R-10 of your target. ENERGY STAR recommends R-60 for a bare attic in climate zones 4 through 8 and R-30 in zone 1. Heat flow falls as one over R, so the last step returns a small share of what the first one did. That R-10 threshold is an editorial judgement labeled as an estimate. The depth checker turns your measured inches into a range before you spend.
• The ceiling is not air sealed. Batts slow heat moving through material. They do nothing about air pouring through the gaps around lights, pipes and the hatch, and a batt laid over an open gap is worse than useless. Air sealing usually earns more per dollar than depth does.
• What is up there is wet, moldy or rodent-fouled. New material laid over it gets bought twice. Remove or add over runs that test first.

Recommended levels above are ENERGY STAR retrofit guidance, based on 2021 IECC Residential Provisions Table R402.1.3. Energy codes cover new building and work done under a permit. They do not usually cover adding insulation to an attic you already have. Which edition applies where you live depends on your state, and often on your city. Your local building department is the only authority on it.

• Attic insulation cost: the installed model and the method
• Blown-in cost, per bag and per square foot
• Insulation cost per square foot, material by material
• Fiberglass batts: fit, facing and what the label means
• Blown-in against batts, on everything but price
• Mineral wool batts
• Cellulose against fiberglass