Blown-In Insulation Cost Calculator
Blown-In Insulation costs $1,025 to $1,550 for a typical 1,000 sq ft job in 2026, against a national benchmark of $1,250. Labor runs 9.5 crew hours at $39.00 an hour. Enter a ZIP code to apply that area's measured wages for this work and its regional price level.
What makes up the price
Cost by size
National averages, before any local adjustment. Computed from the same model as the calculator above, so the two always agree.
| Area to insulate | Sq ft | Typical | Range |
|---|---|---|---|
| 550 sq ft | 550 | $775 | $625 to $975 |
| 800 sq ft | 800 | $1,050 | $850 to $1,300 |
| 1,000 sq ft | 1,000 | $1,250 | $1,025 to $1,550 |
| 1,350 sq ft | 1,350 | $1,625 | $1,325 to $2,000 |
| 1,700 sq ft | 1,700 | $2,000 | $1,625 to $2,475 |
Cellulose or fiberglass
The only real decision on this page, and it is closer than either industry will tell you.
| Blown cellulose | Blown fiberglass | |
|---|---|---|
| 1,000 sq ft to R-49 | $1,875 | $1,750 |
| R per inch | about 3.7 | about 2.6 |
| Depth for R-49 | 13–14 in. | 16–18 in. |
| Weight on the ceiling | 1.5–2.5 lb / sq ft | 0.5–0.8 lb / sq ft |
| Made from | Recycled newsprint, borate treated | Spun glass, largely recycled |
| Water | Absorbs and releases it | Does not absorb it |
| Settling | Yes, allowed for in the design density | Very little |
Choose cellulose if the attic is shallow or has limited headroom over the joists, if the house is in a cold climate, or if air movement through the insulation is a concern. It packs denser — 1.6 to 3 pounds per cubic foot against half a pound — and a denser layer resists air drifting through it.
Choose fiberglass if the ceiling below is old lath and plaster or otherwise not built to carry weight, if there is any history of roof leaks, or if the attic is in a hot humid climate where you would rather the insulation did not take up moisture at all.
And otherwise do not agonize. The difference between a good installation and a careless one — even depth, baffles at the eaves, a sealed hatch, dams around the right light fittings — is worth more than the difference between these two materials.
What it costs
| 1,000 sq ft to R-49 | Per sq ft | |
|---|---|---|
| Fiberglass over existing insulation | $1,250 | $1.25 |
| Fiberglass from bare joists | $1,750 | $1.75 |
| Cellulose over existing | $1,350 | $1.35 |
| Cellulose from bare joists | $1,875 | $1.88 |
| Either, after removing the old material | $2,775–$3,000 | $2.78–$3.00 |
Topping up is the cheapest route to code because loose fill goes straight over dry, uncontaminated insulation and you pay only for the balance of the depth. Removal runs $1 to $2 a square foot — more than the installation that follows — and is genuinely needed only if rodents have nested in it, it is wet or has been, or it is vermiculite, which needs testing for asbestos before anybody disturbs it.
Settling is normal, and it is priced in
Cellulose settles. A layer blown to 15 inches may be 13 inches a year later, and that is not a defect or a short measure — it is a known property, and a competent installer blows to a settled design density so the R-value is reached after settling rather than before it.
What matters is that the number on the quote is the settled R-value. Two things to ask for:
- A depth ruler stapled to a truss, which any decent crew does unprompted. It is a cardboard or plastic scale showing inches, and it lets you check both on the day and in a year.
- The bag count. The manufacturer's bag states the coverage in square feet at a given R-value, so bags divided by area is an arithmetic check on what was actually installed. Ask for the bag count on the invoice and keep it — it is the only hard evidence of depth that survives the crew leaving.
Blown fiberglass settles very little, which is a genuine point in its favor, though it needs the extra depth from the start.
What the hose can and cannot reach
Loose fill is good at open horizontal surfaces and bad at everything else. Worth knowing before somebody quotes to blow the whole house:
- An open attic floor is the ideal case: the hose reaches everywhere and the material self-levels around pipes, wires and bracing that batts would have to be cut around.
- A sloped ceiling or a cathedral ceiling cannot take loose fill unless netting is installed first, and often cannot take it at all.
- A knee wall — the short vertical wall in a finished attic — needs netting or rigid board, because loose fill will not stay in a vertical cavity at attic density.
- A finished wall can be dense-packed, which is a different process: see below.
- Under a floor between joists does not work with loose fill at all; that is batts, or foam.
Dense-pack is the same material at four times the density
If somebody offers to blow insulation into your finished walls, that is dense-pack, and it is not the same job as an attic.
The material goes in at 3.5 to 4 pounds per cubic foot rather than half a pound, through holes drilled in the siding or the plaster, with a tube fed into each cavity. At that density it stays put in a vertical space and resists air movement well enough to act as a partial air barrier, which is the main reason to do it.
It is also $2 to $6 a square foot of wall rather than $1.25 to $1.88 of attic, for an R-13 or so rather than an R-49, because the access is the work: drilling, filling, plugging and patching every cavity, and matching siding or plaster afterwards. It is worth doing in a house with empty wall cavities and an already-insulated attic. It is not the place to start.
What you are paying for
1,000 square feet of blown fiberglass to R-49 over bare joists, at $1,750:
| Labor, about 9.5 hours | around $519 |
| Fiberglass, 1,000 sq ft at R-49 | $500 |
| Baffles, dams, netting and masking | $150 |
| The crew, the truck and the blower | $120 |
| Overhead and margin | the balance |
The blowing itself is about four hours for two people. The hour and a half before it is the part that decides the result: parking the truck where the hose will reach, masking the route through the house, fitting a baffle at every eave so the soffit vents stay open, building a dam around the hatch and around any recessed light not rated for insulation contact, and stapling up the depth ruler.
Air sealing the ceiling plane is a separate line and should come first — $200 to $1,500, and it is the best value in the whole job, because loose fill is air-permeable by design and does nothing about air going up through the holes underneath it.
Questions worth asking
- Cellulose or fiberglass, and why that one in this attic?
- Will you air seal before blowing, and what is that priced at?
- Is the quoted R-value the settled one?
- How many bags, and will the count be on the invoice?
- Will a depth ruler be stapled to a truss?
- Are baffles going in at every eave?
- How are the recessed lights being handled?
- Is the attic hatch being sealed and insulated?
- Does the old material need removing, and which of the three reasons applies?
- Which utility rebates apply, and do you file them?
Common questions
How much does blown-in insulation cost?
About $1,250 for 1,000 square feet of fiberglass blown over existing attic insulation to R-49, or $1,750 from bare joists. Cellulose is a little more: $1,350 topping up and $1,875 from bare. Per square foot that is $1.25 to $1.88. If old insulation has to be removed first, add $1 to $2 a square foot — more than the installation that follows it.
Is cellulose or fiberglass better for blown-in insulation?
Closer than either industry suggests. Cellulose gives R-3.7 an inch against fiberglass's 2.6, so it needs four fewer inches for R-49, and it packs denser so it resists air drifting through it. Fiberglass weighs a third as much, which matters over an old lath-and-plaster ceiling, and it does not absorb water. Choose cellulose for a shallow attic or a cold climate, fiberglass for a weak ceiling or a history of leaks — and otherwise spend the worry on the installer instead.
How deep does blown-in insulation need to be?
For R-49, about 13 to 14 inches of cellulose or 16 to 18 inches of fiberglass. Standard ceiling joists are around 10 inches deep, so in either material the finished layer stands well above the tops of the joists — which is normal and is why you should not be able to walk across a properly insulated attic without a raised platform.
Does blown-in insulation settle?
Cellulose does: a layer blown to 15 inches may be 13 a year later. That is a known property rather than a defect, and a competent installer blows to a settled design density so the rated R-value is reached after settling, not before. What matters is that the quote states the settled R-value. Blown fiberglass settles very little but needs the extra depth from the start.
How do I check I got the insulation I paid for?
Two ways, and ask for both. A depth ruler stapled to a truss — a printed scale in inches — lets you see the depth on the day and a year later. And the bag count: each manufacturer's bag states coverage in square feet at a given R-value, so bags divided by your attic area is an arithmetic check on what went in. Ask for the count on the invoice and keep it, because it is the only hard evidence that survives the crew leaving.
Can blown-in insulation go over existing insulation?
Yes, and it is the cheapest route to code — $1,250 against $1,750 from bare joists on a 1,000 square foot attic, because you pay only for the balance of the depth. Dry, uncontaminated insulation stays. It genuinely has to come out for three reasons only: rodents have nested in it, it is wet or has been, or it is vermiculite, which may contain asbestos and should be tested before anybody disturbs it.
Can you blow insulation into existing walls?
Yes, and it is called dense-pack — the same material at 3.5 to 4 pounds per cubic foot instead of half a pound, blown through holes drilled in the siding or plaster with a tube fed into each cavity. At that density it stays put in a vertical space and acts as a partial air barrier. It costs $2 to $6 a square foot of wall for roughly R-13, against $1.25 to $1.88 for R-49 in an attic, because the drilling, plugging and patching is the work. Worth doing once the attic is done.
Can blown-in insulation be used in a cathedral or sloped ceiling?
Not without netting installed first, and often not at all. Loose fill needs an open horizontal surface to self-level on; on a slope it slumps, and in a vertical cavity such as an attic knee wall it will not stay at attic density. Sloped and cathedral assemblies are usually batts cut to fit with a ventilation channel above, or spray foam applied to the underside of the deck.
Is blown-in insulation messy?
The attic is, briefly. The hose runs through the house, so a good crew masks the route and the floor and vacuums afterwards, and cellulose in particular produces fine dust that can drift through ceiling penetrations — one more argument for air sealing first. Expect a crew of two for half a day and a tidy house at the end; if the quote is cheap and nobody mentions masking, ask.
Does blown-in insulation attract rodents?
Neither material feeds them, and the borate in cellulose is a mild deterrent to insects, but any insulation is good nesting material if animals can already get in. The sequence that matters is to seal the entry points first — gable vents, soffit gaps, the plumbing stack boot, the chimney chase — then insulate. Blowing fresh material over an active rodent problem buries it rather than solving it, and that is one of the three cases where removal is genuinely needed.
Is blown-in insulation fireproof?
Neither is fireproof and both are treated. Cellulose is impregnated with borate, which makes it flame-resistant and is also its insect treatment; it chars rather than supporting flame. Fiberglass does not burn, though it will melt. The real fire question in an attic is not the insulation but what is buried in it: an older recessed light not rated for insulation contact needs a dam around it or replacing with a modern IC-rated or canless unit.
Can I rent a blower and do it myself?
Yes — the machines rent for about $100 a day and are often free with enough bags, and the work is not skilled. Two things make it worth paying somebody: it is hot, itchy and awkward in a confined space with a hose, and the parts that matter most are the ones that are easy to skip. If you do it yourself, air seal the ceiling plane first, fit a baffle at every eave, dam the hatch and any non-IC-rated lights, and keep the depth even — the blowing will look after itself.
Where these numbers come from
Nothing here is copied from a contractor directory. Labor is priced from what the trades are actually paid, materials from published producer prices, and both are adjusted to your area using federal cost-of-living data.
- Drywall and insulation contractors, United States: $39.00/hour, August 2026 (BLS CES CES2023831003)
- Blown fiberglass to R-49: $0.50 per sq ft (price recorded October 2026, not index-adjusted)
- Baffles, dams, netting and masking: $0.15 per sq ft (price recorded October 2026, not index-adjusted)