Pricing Attic Insulation by R-Value and Square Foot

“How do I price blown-in insulation?” Most answers start with a rate per square foot. The rate is fine as an output, but it hides what actually drives the cost: the number of bags it takes to reach the R-value the customer needs, and the work around the insulation that some attics need and others do not. Price those separately and the square-foot figure takes care of itself.

Step 1: the target R-value

The R-value sets everything after it, and it depends on the climate zone. ENERGY STAR publishes the levels it calls cost-effective for retrofitting existing wood-framed homes, based on the 2021 International Energy Conservation Code (IECC). Its “Add Insulation to Attic” column:

The Department of Energy’s table of 2021 IECC minimums for the ceiling of an uninsulated attic gives the same figures: R30 in zone 1, R49 in zones 2 and 3, and R60 in zones 4 through 8. Quote the target as an R-value, never as inches, because the inches depend on the product.

Step 2: the bags, from the coverage chart

A federal rule puts the number you need on the bag. The FTC’s R-value Rule requires loose-fill labels to show, at R-13, 19, 22, 30, 38 and 49, the minimum settled thickness, initial installed thickness, maximum net coverage area, number of bags per 1,000 square feet and minimum weight per square foot, along with the blowing machine and settings used (16 CFR §460.12). Read that chart for the product you blow. Two products at R-49 show why:

The same R-49 takes three times as many bags of one product as of the other, at a different thickness. So never reuse one product’s chart for another, and never price by the inch. The math is: attic floor area ÷ 1,000 × bags per 1,000, rounded up, because the charts give a minimum. For a 1,200-square-foot attic floor that is 28.2 bags of the fiberglass, so 29, or 85 bags of the cellulose.

Then allow for the real world. Greenfiber’s chart says job conditions, technique, equipment and settings can change actual coverage by as much as 10%, and the Department of Energy’s weatherization job aid for attic insulation lets its crews over-blow by no more than 5 bags against the manufacturer’s chart. Track bags used against the chart on your own jobs and price the cushion you actually need.

Step 3: time and the crew rate

The Bureau of Labor Statistics puts the median annual wage for floor, ceiling and wall insulators at $49,120 in May 2025, or about $23.62 an hour over a 2,080-hour year. Payroll taxes, workers’ comp and unbilled hours go on top; your real hourly cost shows how. Say a two-person crew plus the truck and blowing machine costs $96 an hour, or $1.60 a crew-minute. That figure is illustrative; use your own.

Time two parts separately: the fixed part (setting up the hose, protecting the house, cleaning up) and the minutes per bag once you are blowing. Say yours are 60 minutes and 2.5 minutes a bag with the fiberglass above. Cellulose takes more bags for the same R-value, so time it on its own.

Step 4: the work around the insulation, line by line

• Air sealing. The Department of Energy describes blown attic insulation as installed after air sealing on the ceiling deck, and its guidance lists sealing from inside the attic around recessed lights, HVAC registers and other penetrations into the living space, plus drywall joints, with caulk or canned spray foam. Price it by the hour or by the penetration.
• Baffles. DOE says baffles ensure adequate ventilation and keep the insulation from falling into the eaves. Count the rafter bays along each vented eave and price per baffle installed.
• Dams. DOE’s job aid has crews confirm dams around high-temperature items and keep insulation out of the dammed-off areas around chimneys and flues. Price each dam.
• The hatch. If the attic is reached through a hatch or pull-down stair, a dam to hold the loose fill back and an insulated cover are their own line.
• Removal. Taking old insulation out is priced per square foot from your own vacuum time, plus disposal. One exception stops the quote: vermiculite, a pebble-like fill the EPA describes as usually gray-brown or silver-gold. The EPA says a mine near Libby, Montana, supplied over 70% of the vermiculite sold in the United States from 1919 to 1990, that you should assume vermiculite contains asbestos and not disturb it, and that a professional asbestos contractor should handle work that would. Our asbestos abatement page covers that trade.

A worked example

Say a 1,200-square-foot attic floor in climate zone 5 with 3 to 4 inches already there, so the ENERGY STAR column says add R49. It has two 40-foot vented eaves with rafters every 24 inches, so 40 baffles, and a pull-down stair. The material prices and the 40% margin are illustrative.

Each price is the cost divided by 0.60; markup vs. margin explains why you divide. The insulation line alone works out to $1.70 a square foot, and the whole job to $2.72. That gap is the reason a single per-square-foot rate fails: applied to every attic, it overcharges the one that needs only insulation and loses money on the one that needs everything. As a check on the insulation line, HomeAdvisor’s blown-in insulation guide, updated June 17, 2026, says most homeowners spend between $987 and $2,335.

Put the same numbers on the receipt

The figures you priced from are the ones the customer is owed afterward. For blown insulation the FTC rule requires a receipt with the coverage area, initial installed thickness, minimum settled thickness, R-value and number of bags used, and it requires you to show the manufacturer’s fact sheet before the customer agrees to buy. The FTC’s R-Value Rule covers both, and the claims your ads may not make.

Quote the range before the visit

Every input here is something a homeowner can answer, roughly, from the hallway: the attic floor area, the depth they want, the material, whether old insulation comes out, how many eave bays need baffles, whether to seal first and whether to box the hatch. If you want that range on your own website, NapkinPrice™ asks those questions and shows a price range from rates you set, and sends jobs such as vermiculite to a site visit instead of a price. The insulation page shows how it is set up.