Attic insulation cost dataset

The four materials, same attic, same target

National figures before any regional adjustment, for a 1,500 square foot attic in climate zone 4 with four inches of blown fiberglass already in place, air sealed, with baffles, an insulated hatch cover and two non-IC light covers. Only the material changes between the rows.

Open-cell foam is not an expensive version of the others. It is priced by the board foot over the roof deck rather than by the cubic foot over the ceiling, so it insulates a surface about 20% larger than the attic footprint and brings the ducts and the water heater inside the envelope. Comparing its total against a blown figure compares two different jobs.

R-value target by climate zone

The target is our estimate, set in three broad bands rather than copied from a code table we cannot publish. What binds in your state is whichever edition of the energy code it has adopted. Figures below are blown fiberglass over four existing inches, nationally.

What the installation receipt has to show

For loose fill, 16 CFR 460, Labeling and Advertising of Home Insulation requires the installer to hand over a dated contract or receipt showing the coverage area, the initial installed thickness, the minimum settled thickness, the R-value and the number of bags used. The calculator derives all five. Below is the default case: 1,500 square feet, zone 4, blown fiberglass over four existing inches.

The bag count is the only field on that list nobody checks, and it is the only one that cannot be faked after the fact: the empty bags are still in the truck. Count them.

Labour hours modelled

• 5 crew-hours of mobilisation: truck, hose, floor protection, and taking it all back down. It does not scale with the size of the attic, which is why small jobs come back at a job minimum.
• 0.008 h per sq ft for air sealing, crawling the whole ceiling plane before any insulation goes in.
• 0.004 h per sq ft plus volume ÷ 130 to blow loose fill, because blowing twenty inches takes about twice as long as ten over the same floor. Batts are 0.010 h per sq ft instead, since the work is cutting and fitting.
• 0.16 h per baffle, 0.65 for the hatch cover, 0.75 for the flue dam, 0.5 per light cover and 0.75 for the retention dams. Accessories with parts but no hours are the commonest gap in a published breakdown.
• 12% of crew hours plus 0.5 h for the crew lead, who sets out the job, checks the depth against the markers and signs the receipt.
• All of the above are multiplied by the access factor: 0.9 for walk-up stairs, 1.0 for a pull-down, 1.12 for a ceiling hatch and 1.35 where the clearance is under three feet and the crew works lying down.

The wages behind these hours are official BLS figures for your metropolitan area, for insulation workers. The hours themselves are our estimate. Worth saying plainly: this trade has the lowest published wage on this site, so the labour side of these figures runs below what a real invoice bills, and we would rather say that than inflate the hours until the total looks right.

Line items

The four material lines are alternatives, never combined. Conditional lines appear only when the corresponding answer is yes, and the spray foam path drops the baffles, the hatch cover and the light covers entirely, because the insulated boundary moves to the roof.

The reasoning behind each figure

Written out so an insulation contractor can point at the exact assumption that is wrong. A number with no reasoning behind it cannot be corrected.

Site protection and attic setupestimated, ±56%

• Floor and stair coverings on the route to the attic, a drop cloth under the access, temporary lighting, and walkboards laid over the joists so nobody puts a foot through the ceiling below.
• The bottom of the band is a hatch in a garage with a concrete floor. The top is a pull-down stair in a carpeted hallway, where everything on the path has to be covered before a single bag goes up.
• This is protective material only. The time spent laying it and picking it up is on the mobilisation line, not here.

Crew mobilisation, setup and clean-up

• Loading the truck, running a hundred feet of hose, laying the protection, and taking it all back down again. It costs the same on a 400 square foot attic as on a 1,500 square foot one, which is why it is its own line instead of being smeared across the square footage.
• This is also where the blowing machine sits. A contractor owns one and bills nothing for it separately; the big-box stores lend one free when you buy enough bags. It is the one piece of equipment in this trade that is routinely free, so there is no rental line on this page.
• Below roughly 500 square feet, expect a real quote to come back at the installer’s job minimum rather than at a calculated figure. Every crew has one, and no calculator can know yours.
• Metro-adjusted wage from official BLS data. The hours are our estimate; no public source publishes productivity for residential insulation work.

Air sealing materials: caulk, foam, rigid covers and gasketsestimated, ±51%

• Fire-rated caulk and canned foam at top plates and at plumbing and wiring penetrations, plus rigid board and mastic to cap open soffits, dropped ceilings and bath fan housings. These are the leaks that matter; the ones you feel around a window are not.
• The hatch cover and the flue clearance dam are the two largest openings in most ceilings and they have their own lines below. They are deliberately not counted here as well.
• The band is wide on purpose, because it is set by how many holes the house has rather than by the price of sealant. A 1990s house with a simple ceiling plane sits at the bottom; a 1920s balloon-framed house with open stud bays running to the attic sits at the top and deserves it.
• Priced per square foot of attic floor because that is the only figure a homeowner can supply. The real driver is the number of penetrations, which nobody knows until the insulation comes back.

Air sealing labour

• Crawling the whole attic on hands and knees, finding every penetration and sealing it before any insulation goes in.
• This is the single line most often missing when one quote comes in far below another, and it is also the line that decides whether the insulation performs the way its R-value says it will. Turning it off on this page shows you exactly how much of the gap between two quotes it accounts for.
• Tightening a ceiling changes how a house breathes. Where there are combustion appliances, that is a reason to have them checked, not a reason to skip the sealing.
• Metro-adjusted wage from official BLS data; the hours are our estimate.

Insulated and gasketed attic hatch or stair coverestimated, ±58%

• An uninsulated pull-down stair is a hole in the ceiling roughly the size of an open window, left open all winter. Insulating around it and leaving it bare undoes a meaningful share of what was just paid for.
• The bottom of the band is a rigid foam box built on site over a scuttle hatch. The top is a manufactured, gasketed and latched cover sized for a pull-down stair.
• Not needed where spray foam at the roof deck brings the whole attic inside the envelope: the hatch then opens onto conditioned space.

Sheet metal clearance dam around chimneys and appliance ventsestimated, ±53%

• Insulation has to be held clear of masonry chimneys and metal flue vents, and the way that is done is a collar of sheet metal that stops loose fill drifting back against the pipe.
• Modelled at one per house, because most houses have at least one chimney, water heater vent or furnace flue passing through the attic. An all-electric house with none is one line to strike from the quote.
• The band is a single collar at the bottom and a fabricated dam around a masonry chimney at the top.

Fire-rated covers over recessed lights not rated for insulation contactestimated, ±51%

• A recessed light that is not rated for insulation contact has to stay clear of the insulation. Burying it is both a code violation and a fire risk, and the fix is a rated cover over each fixture, sealed to the ceiling.
• Count only the fixtures that are NOT marked IC. A modern airtight IC-rated can needs nothing at all, and counting those is how this line gets inflated.
• The band separates a rigid foam or mineral wool box at the bottom from a manufactured steel or fibreglass cover at the top.
• This is a classic quote-versus-invoice surprise: the lights are not visible from the attic access, so they get counted after the crew is already up there.

Eave vent bafflesestimated, ±64%

• Adding depth buries the eaves and blocks the soffit vents. Baffles hold a channel open from the soffit to the ridge so the roof deck still gets air. Without them the new insulation causes condensation on the sheathing and, in cold zones, ice dams at the eave.
• Quantity is one per rafter bay along two eaves, at the spacing you tell us: 16 inches in a house framed with rafters, 24 in a house built with trusses. A house from the 1970s is almost always 16, and assuming 24 undercounts it by half.
• A long, narrow attic needs more than this; a hip roof with four vented eaves needs about twice as many.
• The band separates thin polystyrene chutes at the bottom from rigid, taped-in-place baffles at the top. The cheap ones work if they are fastened properly.
• Baffles keep an existing vent channel open. They do not create ventilation where there is none: see the exclusions.

Retention dams at the access, the eaves and any whole-house fanestimated, ±55%

• At sixteen or twenty inches, loose fill has to be dammed or it spills out over the soffit and pours through the stair opening every time the hatch is pulled down. Rigid board or fibre dams do it.
• This is not the hatch cover: the cover closes the hole, the dam is what stops the fill falling through it while the hole is open. Both appear on real invoices.
• Cheap, always there, and left out of almost every published cost guide.

R-value depth markersestimated, ±56%

• Markers fixed to the joists or trusses roughly every 300 square feet, showing the installed thickness, so that anybody can walk in later and check the depth against what was charged for.
• Pennies as a line item and the cheapest verification on this page. If a quote leaves them out, ask why: their absence is what makes an under-blown attic impossible to prove.
• Loose fill only. With batts or foam the thickness is set by the product, not by how much was blown.

Fitting the baffles, dams, covers and hatch

• The hours that go with the parts above, and the single biggest gap in most published breakdowns: nobody staples fifty-odd baffles lying down in an eave for free, and nobody seals a fire-rated cover over a light fixture for free either.
• Modelled at about 0.16 hours per baffle, 0.65 for the hatch cover, 0.75 for the flue dam, 0.5 per light cover and 0.75 for the retention dams, all multiplied by the access factor.
• Add a light to the form and this line moves with it. That is the test of whether a breakdown is real: if the labour does not respond to the count, it was never in there.
• Metro-adjusted wage from official BLS data; the hours are our estimate.

Blown fiberglass insulation, deliveredestimated, ±36%

• Priced by the cubic foot of settled material, because that is what actually scales. The same square foot of attic takes twice the material at R-60 as at R-30, so a price per square foot that does not name an R-value means nothing.
• The bottom of the band is a contractor buying by the pallet. The top is a homeowner paying counter price for a handful of bags, which is genuinely what the store charges. Insulation is bulky to ship, so freight moves this more than the product does.
• R-2.2 to R-2.7 per inch settled; the model uses 2.5. It is a band and not a single figure because the value falls as the blanket gets thicker. The FTC R-value rule, 16 CFR 460.20, tells manufacturers not to publish a single “R-value per inch” for a product at all, and where a range is published it has to be accompanied by a statement that the thicker the insulation, the lower the R-value per inch. That rule binds the label on the bag rather than this page, but the physics behind it is why the band is here.
• Blown fiberglass barely settles once it is in, but it is placed by eye. Depth markers and the bag count on the receipt are what turn that into something checkable.

Blown cellulose insulation, deliveredestimated, ±36%

• The cheapest way to buy R-value on this page, and it is a double saving: cellulose costs less per cubic foot and delivers more R per inch, so it needs roughly 30% less depth for the same result.
• Recycled paper treated with borate for fire and pest resistance. It is heavier than fiberglass, which matters on an old ceiling with 2x4 joists and lath below, and it is dustier to install.
• The top of the band is retail counter price for bags bought a few at a time, which is the case that matters here, because cellulose is also the cheapest do-it-yourself route. The bottom is contractor pallet pricing.
• R-3.2 to R-3.8 per inch at settled density; the model uses 3.5. Loose-fill cellulose is rated at settled density, so it is deliberately blown thicker than the final figure. The receipt has to show both thicknesses, and this page calculates both.
• Cellulose takes up and releases moisture, which is an advantage in a dry attic and a liability under a roof that leaks. Fix the roof first.

Unfaced fiberglass batts, R-30estimated, ±21%

• Batts come in fixed R-steps, so unlike loose fill you cannot buy exactly the R you need. The model picks the smallest step that reaches the target and prices that step: this is the R-30 line.
• Because there are three priced steps, the climate zone moves the material cost on this path too. A single band across all steps would have told a Florida attic and a Minnesota attic that their insulation cost the same, which is the exact error this page exists to correct.
• Unfaced, because a vapour retarder laid on top of existing insulation traps moisture inside the assembly.

Unfaced fiberglass batts, R-38estimated, ±18%

• The middle standard step. Priced separately from R-30 and R-49 so the material cost responds to the R-value, which is the whole argument of this page.
• In a retrofit attic batts are usually the wrong answer, and the reason is fit rather than price: they have to be cut around every wire, pipe and brace, and a batt with a two-inch gap beside it loses far more than two inches worth of performance. Loose fill flows into those places by itself.
• Unfaced, for the same moisture reason as the other batt steps.

Unfaced fiberglass batts, R-49estimated, ±17%

• The thickest standard batt, and the top of what this route can reach in one layer. Where the target needs more than R-49, batts stop being a sensible answer and the honest recommendation is loose fill.
• Laid over existing loose fill, batts bridge the joists rather than conforming to them, leaving air channels underneath. Where they do make sense is a clean, accessible attic with uniform joist spacing and nothing in the way.
• Unfaced, for the same moisture reason as the other batt steps.

Open-cell spray foam on the roof deck, installedestimated, ±25%

• Priced by the board-foot, which is one square foot at one inch, because that is how spray foam is bought and sold and it is the only unit that scales with depth. Reaching a zone target of R-60 at R-3.5 per inch takes seventeen inches, and a per-square-foot price that ignores that is off by a factor of three.
• This is an INSTALLED price: the two-component chemical, the rig, and the crew that sprays it. There is no separate labour line for this path, because adding one would charge for the foam crew twice.
• Quantity is roof deck area, not attic floor: the sloped surface is about 20% larger than the footprint under it, which is the geometry of a 4:12 to 8:12 roof plus gable ends.
• This is a different job, not a cheaper material. Foam on the roof deck moves the insulated boundary from the ceiling to the roof and turns a vented attic into a sealed, semi-conditioned space, bringing the ductwork and the water heater inside the envelope. That is the real reason to do it.
• An unvented attic assembly has condensation-control requirements that vary by climate zone, and in cold zones an open-cell-only assembly can wet the sheathing from below. That is a decision for a designer who has seen the roof, not for a calculator.
• Existing floor insulation normally comes out first, because leaving it in place puts insulation on both sides of an air space with no way to dry. Tick the removal option alongside this one.

Insulation installation labour

• Hauling bags up, blowing to depth, working the eaves and setting the markers. Hours scale with volume as well as with area, because blowing twenty inches takes about twice as long as blowing ten over the same floor.
• Batts are priced per square foot instead, since the work is cutting and placing rather than moving material.
• There is no line here for spray foam at the roof deck: that price already includes the crew that sprays it.
• In an attic with under three feet of clearance the target depth cannot physically be reached out at the eaves, so the real result is less than the R-value on the quote across part of the floor. The access factor lengthens the hours but does not pretend to fix that, and no calculator can.
• The wage is official BLS data for insulation workers, floor, ceiling and wall, adjusted to your metropolitan area. The hours are our estimate. BLS publishes this occupation in only 135 of 530 areas; outside those the model falls back to the broader construction and extraction wage for your area rather than inventing a number.

Bagging, haulage and tipping fees for the old insulationestimated, ±43%

• Charged by the cubic foot removed, not by the square foot of attic, because what you pay for is volume: taking out twelve inches is three times the bags, three times the trips and three times the tipping fee of taking out four.
• Old attic insulation is light but enormous in bulk. The band covers disposal bags, the trip to the transfer station and the tipping charge, which varies several times over between a rural county facility at the bottom and a metropolitan construction and demolition site at the top.
• Wet, rodent-fouled or fire-damaged insulation sits at the top of the band and sometimes above it, because some facilities will not take it in ordinary loads.

Insulation removal labour

• Vacuuming loose fill out, pulling batts by hand, bagging everything and carrying it down through the house. It is dirty, hot work in full protective equipment, and it scales with the volume coming out as well as with the floor area.
• The removal vacuum is not a separate line. A removal contractor owns a truck-mounted one and bills nothing for it; a homeowner doing it by hand and by bag spends the time instead, which is what this line measures.
• Worth saying plainly: most attics do not need this at all. Settled fiberglass or cellulose that is dry and clean can be blown straight over, and that is both cheaper and normal. Removal earns its place when the material is wet, mouse-infested or smoke-damaged.
• Metro-adjusted wage from official BLS data; the hours are our estimate.

Crew lead: set-out, depth verification and the installation receipt

• A crew is not a crew of one. Somebody sets out the job, checks the finished depth against the markers, and signs the installation receipt. That person is a supervisor and does not cost what a helper costs.
• Modelled at about 12% of the crew hours plus half an hour of paperwork. Small money, but it is the difference between modelling a crew and modelling a labourer working alone.
• The paperwork is not a formality. Federal rule 16 CFR 460.17 requires the installer to give you a contract or receipt, and for loose-fill it must show the coverage area, the initial installed thickness, the minimum settled thickness, the R-value and the number of bags used, dated and signed. This calculator tells you what that bag count should be before the crew arrives.
• Metro-adjusted wage from official BLS data; the hours are our estimate.

Not included in this dataset

Vermiculite insulation, and any asbestos work

If the loose fill in your attic looks like small grey-brown or silver-gold pebbles rather than fluff, it is vermiculite, and vermiculite sold for insulation in the United States may contain asbestos. That is not an insulation job and it is not priced anywhere on this page. It requires testing first and then licensed, trained abatement contractors working under containment, and putting a low number against it would be worse than putting none. Do not disturb it, do not vacuum it, and get it assessed by a licensed asbestos professional before anyone goes into the attic.

Attic ventilation upgrades: soffit vents and ridge vent

Baffles keep an existing air channel open; they do not create ventilation where there is none. Plenty of 1970s houses with continuous aluminium soffit have nominal venting and very little real free area, and going to a deep insulation level is when that shows up. Adding soffit vents or a ridge vent is separate roofing work with its own price, and it is deliberately excluded rather than averaged in.

Electrical work in the attic

Three things routinely come up and none is priced here. Knob-and-tube wiring, which many jurisdictions prohibit burying under insulation, so the job stops until an electrician confirms it is dead or replaces it. Junction boxes, which have to stay accessible once the fill gets deeper than they are. And swapping non-IC recessed fixtures for airtight IC-rated units, which is sometimes better value than covering them. All three are an electrician’s work, not an insulator’s.

Bath and dryer fans that vent into the attic

They are supposed to discharge outdoors and a surprising number do not. It is almost always found during air sealing, because the crew is looking at exactly those penetrations. Rerouting a fan to a roof or gable termination is separate work, priced per fan.

Duct sealing and duct insulation

Ductwork running through a vented attic loses heat to a space that is, by design, at outdoor temperature. Sealing and insulating it is often better value per dollar than the last few inches of R-value, but it is a separate trade and a separate line.

Roof leaks, rotten sheathing and existing mould

Old insulation hides all three, and removal is how they get found. Nothing on this page fixes a roof, and insulating under one that leaks wastes the insulation as well as the money.

Knee walls, bonus rooms and attic storage decking

These figures cover the flat attic floor. A finished bonus room with sloped ceilings and knee walls is a different assembly at a different price per square foot, and raising a storage platform so the insulation can run underneath it is separate carpentry.

A blower door test or a full home energy audit

The right way to know how leaky a house is, and the right way to prove the air sealing worked. It is a separate service with its own price and it is not folded into these figures.

Permit fees and inspections

Some jurisdictions require a permit for insulation work, particularly where it is tied to a rebate or a code upgrade, and some require an inspection before the insulation is covered. Fees vary by jurisdiction with no national source, and are excluded rather than averaged into a figure that would be wrong everywhere.

Tax credits, utility rebates and grant programmes

Nothing is deducted from the figures on this page. One dated fact rather than a promise: the IRS states that the Energy Efficient Home Improvement Credit could be claimed "for improvements made through December 31, 2025", and ENERGY STAR states the insulation credit was "effective for products purchased and installed between January 1, 2023, and December 31, 2025". Cost guides that still advertise 30% off insulation are describing a window that has closed. Utility and state programmes are local, change constantly, and are not modelled. This is a statement of what those two federal pages say on the date shown, not tax advice; check your own position with the IRS or a tax professional.