Most of our projects run between $3,500 and $12,500. Blowing more insulation onto an open attic floor is the least expensive work in most houses; a crawl space that gets lined, sealed and insulated costs more, and so does filling a finished wall through holes.
National cost guides say the same thing from a distance. HomeGuide’s insulation cost guide, dated December 2025, puts installed insulation at $1.00 to $4.50 per square foot and the average whole-house job at $1,600 to $8,000. Angi’s, updated May 2026, puts the average installation at $1,859 within a $500 to $4,500 range. Both are averages of other people’s projects in every climate, not a quote for your house and not our price. Our range sits higher because our jobs usually combine several of the line items priced below: air sealing, taking old material out, and more than one part of the house.
Insulation cost per square foot
Installed, per square foot, HomeGuide’s insulation cost guide lists:
- Batts and rolls (fiberglass, mineral wool): $0.80 to $2.60.
- Blown-in (cellulose, fiberglass): $1.00 to $2.80.
- Rigid foam board: $1.20 to $3.70.
- Spray foam costs the most per square foot. Its figures, by the square foot and the board foot, open and closed cell, are in our spray foam insulation cost guide.
HomeGuide splits that into $0.50 to $2.80 per square foot of material and $0.50 to $1.70 of labor. Fixr’s home insulation guide, updated January 2026, puts a 2,000-square-foot house done in fiberglass batts at $4,700 on average, within $2,000 to $7,400, and warns that the figure leaves out opening and refinishing walls.
A square-foot price means little until you know which square foot and how deep. An attic floor is measured as floor; basement and crawl space walls as wall area, not floor space; a roofline as the underside of the deck. And a price for 6 inches of loose fill buys something different from a price for R-60.
What drives an insulation price up or down
- Area. Bigger jobs cost more in total and often less per square foot. Small jobs hit minimums: HomeGuide’s attic guide, dated January 2026, says some insulation companies have a $1,500 to $2,000 minimum project requirement.
- Access. HomeGuide lists crawl spaces, odd-shaped attics and finished drywall or siding as conditions that raise labor; low eaves and knee walls add hours too.
- Depth, set by the R-value target. The ceiling requirement is R-49 under the 2024 IECC New Jersey adopted and under New York’s 2025 energy code, and R-60 under the 2021 IECC Connecticut uses. A New Jersey permit application filed under the state’s previous 2021 code, which is allowed until mid-February 2027 (N.J.A.C. 5:23-1.6), stays at R-60. More R-value is more material: HomeGuide’s blown-in guide, dated November 2025, prices R-49 at $1,100 to $1,900 per 1,000 square feet and R-60 at $1,400 to $2,400.
- Air sealing, included or not. HomeGuide puts air sealing an attic at $350 to $3,000 and notes that some contractors include it in the insulation estimate.
- Old material coming out. Removal is priced under attic insulation replacement, below. HomeGuide’s removal guide says it costs much more when the material is damaged or potentially hazardous, and that some contractors set a minimum fee for sanitizing an attic.
- Fire and ignition barriers. Foam insulation has to sit behind a thermal barrier, 1/2-inch drywall being the usual one (Section R316.4 of the 2021 IRC in Connecticut; R303.4 of the 2024 IRC in New Jersey and of New York’s 2025 Residential Code, which is based on it). Attics and crawl spaces entered only for repairs or maintenance can get a lighter ignition barrier instead. Ask whether a foam quote includes the barrier.
- Finished or unfinished space. Open framing is the cheapest place to insulate. Angi’s May 2026 guide says new construction costs around $1 less per square foot than an existing home.
Attic insulation cost
HomeGuide’s January 2026 attic guide puts attic insulation at $1 to $4 per square foot installed, $1,000 to $2,700 for the average job, and blown-in at $0.90 to $2.40 per square foot. Angi’s December 2025 guide gives $1 to $3 per square foot and a $2,100 average within $1,700 to $2,500.
Where the insulation goes matters more than any per-foot figure. The Department of Energy’s Building America insulation guide names loose-fill fiber and fiberglass batts as the cheapest insulation types and good choices for a vented attic floor, and says adding insulation to attics is usually easy and cost-effective at any time, with a new roof the ideal moment. Insulating at the roofline instead is a different job at a different price; see roof insulation cost, below.
On a floor job, the number moves with:
- What is up there now. ENERGY STAR’s table of cost-effective levels for climate zones 4A, 5 and 6 calls for R-60 where the attic has none and R-49 where 3 to 4 inches already sit on the floor. Topping up costs less than starting from bare joists.
- The sealing underneath. Top plates, the chimney chase, plumbing and wiring holes, recessed lights and the hatch get sealed before depth goes on. Where an attic is buried in old loose fill, reaching them can mean vacuuming part of the floor first.
- The edges. Baffles at the soffit vents, dams around fixtures, an insulated and weatherstripped hatch. HomeGuide notes that multiple fixtures needing dams and air sealing raise the cost.
See attic insulation.
Attic insulation replacement cost
Replacement adds removal. HomeGuide’s removal guide, dated November 2025, puts taking attic insulation out at $1 to $2 per square foot, $1,600 to $3,600 on average, and removal plus new insulation at $2 to $6 per square foot, $3,200 to $10,800. Angi’s, updated May 2025, gives the same $1 to $2 per square foot, a $900 average within $600 to $1,200, and up to $1 more per square foot for areas that are hard to reach. HomeGuide adds that blown-in insulation costs more to remove than batts, and that insulation with debris mixed in comes out by hand.
Removal is worth paying for only when the old material has to go. Fixr’s January 2026 guide says to always remove old insulation first and prices it at $1 to $3 per square foot. ENERGY STAR’s do-it-yourself guide disagrees for insulation darkened where house air filtered through it: “Although the insulation is dirty, it is still okay to use. There’s no need to remove and replace.” Our rule: wet, rodent-soiled, fire-damaged or crushed insulation comes out; insulation with mold on it goes out as part of a remediation company’s work, after the moisture is fixed; dry insulation that is only thin gets sealed around and topped up.
We do the removal ourselves, under containment and into a HEPA-filtered insulation vacuum, and cleaning up a rodent-soiled attic is part of that work. Two costs never belong in an insulation quote. Mold on the insulation or the framing goes to a remediation company; HomeGuide’s attic guide puts attic mold removal at $1,500 to $15,000. Vermiculite, a pebble-like fill the EPA describes as usually gray-brown or silver-gold, should be treated as asbestos and left undisturbed; it goes to a licensed abatement contractor, as does old pipe wrap that may contain asbestos. HomeGuide lists asbestos removal at $10 to $25 per square foot. We insulate once the attic is clean and dry.
Blown-in insulation cost
HomeGuide’s blown-in guide, dated November 2025, gives $1.00 to $2.80 per square foot installed: $900 to $3,600 for an attic floor, and $1,900 to $7,800 for all the exterior walls of a 2,000- to 2,500-square-foot house. By material, installed, it lists cellulose at $1.20 to $2.80 per square foot, fiberglass at $1.00 to $2.80 and blown rock wool at $1.90 to $4.20, with dense-pack cellulose in walls at $1.60 to $4.20. Angi’s, updated November 2025, puts the average blown-in job at $1,657 within $985 to $2,330; Fixr’s, updated August 2025, averages $1.65 to $3.80 per square foot.
Cellulose, at about R-3.2 to R-3.8 per inch, reaches a target in fewer inches than loose-fill fiberglass. HomeGuide’s blown-in guide notes that it is denser, takes more bags for the same depth, and settles about 10% after installation, while loose-fill fiberglass settles little or not at all. Compare quotes on the R-value delivered, not on inches or the product name.
You can check a blown-in quote from the bag. Under the Federal Trade Commission’s R-value Rule (16 CFR 460.12), every loose-fill package carries a chart with the number of bags per 1,000 square feet, the initial installed thickness and the minimum settled thickness at R-13, R-19, R-22, R-30, R-38 and R-49, plus any other R-value the maker chooses to list; an R-60 row is there only if the maker adds one. Divide your attic floor area by 1,000, then multiply by the bags per 1,000 square feet at your target. HomeGuide’s blown-in guide lists 24 to 26 bags per 1,000 square feet at R-49, which works out to roughly 36 to 39 bags for a 1,500-square-foot attic; the chart on the product in your quote is the one that counts.
Crawl space encapsulation cost
HomeGuide’s encapsulation guide, dated January 2026, puts crawl space encapsulation at $3 to $10 per square foot, $3,000 to $15,000 total. This Old House’s, updated March 2026, puts the average at $5,500 within $1,500 to $15,000: basic jobs at $3 to $7 per square foot, up to $10 where moisture problems are extensive, with labor 50% to 70% of the total.
“Encapsulation” is several jobs under one word, and a good quote prices them separately. HomeGuide’s breakdown:
- Ground liner: $1,200 to $4,000 installed, about $2 to $4 per square foot. Liner weight moves it: 6-mil at $0.30 to $0.35 per square foot against 20-mil at $0.60 to $0.70, material only.
- Sealing vents and holes: $150 to $450.
- Insulation: $500 to $3,700.
- Dehumidifier: $1,000 to $3,000 with installation.
- Cleaning or repairs, if needed: $500 to $8,000.
- Interior drainage, where water gets in: $800 to $3,000.
A crawl space moisture barrier on its own is the smallest version: a sealed liner over the ground in a crawl space that stays vented. Full encapsulation closes the vents, seals the liner to the foundation walls and dries the air. For an unvented crawl space, Section R408.3 of the International Residential Code sets the minimum, in the 2021 edition Connecticut uses, the 2024 edition New Jersey adopted and New York’s 2025 Residential Code: a continuous Class I vapor retarder over the ground, its edges run at least 6 inches up the wall and sealed, plus one of four drying methods. Those are continuous exhaust, a conditioned-air supply, the crawl space used as a plenum in an existing house, or a dehumidifier sized to the maker’s specifications. The energy code then requires the walls of an unvented crawl space to be insulated (Section R402.2.10 of the 2021 IECC in Connecticut, R402.2.11 of the 2024 IECC in New Jersey and of New York’s 2025 energy code). For insulation alone, HomeGuide’s crawl space insulation guide, dated December 2025, gives $1.00 to $4.50 per square foot, $500 to $3,700 on average.
We lay and seal the liner, seal the vents and rim joists, insulate the walls, and pull out fallen or soiled batts. Drainage goes to a waterproofing contractor. A dehumidifier is priced as its own line and we can walk you through that option; a supply register or exhaust fan is HVAC work. The price moves most with the crawl space height and obstructions, the wall area (height times perimeter), the liner weight, and whether water has to be fixed first. See crawl space insulation.
Basement insulation cost
HomeGuide’s basement guide, dated February 2026, gives $1 to $5 per square foot of the surface insulated, wall or ceiling, not of floor space. By type, installed: fiberglass batts $1.00 to $2.60, wool insulation (mineral wool included) $1.50 to $3.80, rigid foam board $1.20 to $3.70, spray foam $1.50 to $5.00. Angi’s May 2026 guide puts basements at $1.50 to $2.50 per square foot, $1,400 to $6,300.
- Walls or ceiling. A finished or heated basement, or one holding the furnace and ducts, gets its walls and rim joists insulated. A dry, unheated, unused one can get its ceiling instead; see basement ceiling insulation.
- What covers the foam. Board or spray foam on basement walls needs the code’s thermal barrier. HomeGuide puts framing at $18 to $24 per linear foot and drywall at $1.50 to $3.50 per square foot of wall. Ask whether either is in the price.
- Rim joists. The Department of Energy’s guide says that when insulating the entire basement is too expensive, sealing and insulating the rim joists alone will save energy and improve comfort.
- Water. A wall that leaks goes to a waterproofing contractor before anything is insulated. HomeGuide lists basement waterproofing at $6,000 to $18,000, a separate trade’s price and never part of an insulation quote.
More on walls, rim joists and floors: basement insulation.
Wall insulation cost
HomeGuide’s wall guide, dated September 2025, gives $1 to $5 per square foot installed, or $1,700 to $8,500 for the exterior walls of an average 2,000-square-foot house. Its blown-in guide, dated November 2025, puts blown-in wall insulation at $1.10 to $3.70 per square foot. Angi’s May 2026 guide says $1 to $4. Whether the wall is open or closed decides most of it.
- Open walls, in new construction or a gut renovation: the Department of Energy’s guide says filling open cavities with fiberglass or cellulose will be inexpensive, and that spray foam or rigid board costs much more but seals better against air and moisture.
- Closed walls: dense-pack cellulose or injection foam through holes drilled in the siding or drywall. HomeGuide describes 1-inch holes and puts siding repair at $10 to $100 or more per hole, depending on the siding. We do both methods. Our written scope states how the holes get closed and whether finish work, such as paint or matching siding, is in our price or goes to a painter or siding contractor; ask every quote the same question.
- Re-siding: ENERGY STAR’s retrofit guidance says that whenever siding comes off an uninsulated wall, blow insulation into the empty cavities, and in zones 4 through 8 add R-5 to R-10 insulating sheathing under the new siding.
Knob-and-tube wiring still in service is an electrician’s job and an electrician’s bill; the Department of Energy wants it replaced before any insulation goes in. See wall insulation.
Garage and roof insulation cost
Garage insulation cost
HomeGuide’s garage insulation guide, dated November 2025, gives $0.50 to $3.00 per square foot installed and $800 to $5,100 for the walls and ceiling of an unfinished two-car garage. Finished walls and ceiling push the same job to $1,600 to $12,800, because the drywall comes off and goes back, or gets drilled and patched.
What gets insulated matters more than the garage’s size. The wall shared with the house and the floor of any room above the garage are what separate heated rooms from an unheated space, and the energy code requires air sealing between the garage and the house (Table R402.5.1.1 of the 2024 IECC in New Jersey and of New York’s 2025 energy code, Table R402.4.1.1 of the 2021 IECC in Connecticut). Insulating the outside walls and the overhead door changes the garage’s own temperature, which is worth paying for mainly in a heated garage or workshop. A drywalled ceiling under a bedroom can often stay up, because we dense-pack the floor above through holes in it. The gypsum between garage and house is required fire separation (IRC Section R302.6, in each state’s edition), so anything opened goes back to the same protection. See garage insulation.
Roof insulation cost
HomeGuide’s roof insulation guide, dated November 2025, puts insulation under the roof deck at $2 to $7 or more per square foot, $2,000 to $7,000 or more for a 1,000-square-foot roof, against $1 to $4 for an attic floor. Installed, it lists batts at $2.00 to $3.75 per square foot and rigid foam board at $2.50 to $6.00; foam figures are in the spray foam cost guide. Its attic guide adds that the roof’s larger surface takes more labor and material than the attic floor, and the roof guide names complex roof shapes with dormers or skylights as an added cost.
The roof deck is the right place when there is no usable attic floor, as under a vaulted or cathedral ceiling, when ductwork or heating and cooling equipment sits in the attic, or when the attic is becoming storage or a room. HomeGuide’s roof guide says attic floor insulation is less effective with ducts or equipment up there. The Department of Energy’s Building America guide calls the rigid or spray foam a sealed roofline needs much more expensive than fiberglass batts or blown fiber, says it may be cost-effective when you are reroofing or creating an attic room, and lists better efficiency with ducts in the attic among its advantages. Foam under the deck needs a thermal barrier unless the attic is entered only for repairs or maintenance (Section R316.5.3 of the 2021 IRC, R303.5.3 of the 2024 IRC and New York’s 2025 code). The roofing itself is a roofer’s work. See roof insulation.
How to read an insulation quote
Per square foot or per job, either is fine if the quote shows its work. HomeGuide tells homeowners to ask for a firm, itemized bid, and federal law already sets a floor for what the paperwork shows. Under the FTC’s R-value Rule (16 CFR 460.17), an installer must give you a dated, signed contract or receipt with the coverage area, thickness and R-value for each part of the house, never added together, and for loose fill the initial installed thickness, minimum settled thickness and number of bags. A quote you can compare lists, for each area:
- The area and how it was measured: attic floor, wall area or roof deck.
- Material, R-value and depth. For loose fill, the bag count.
- Air sealing, place by place: top plates, chases, penetrations, recessed lights, rim joists, the hatch. A quote that lists inches of insulation and says nothing about air sealing is half a job.
- Removal and disposal, with the reason it is needed and how the house is protected.
- Edge details: vent baffles, fixture dams, hatch insulation and weatherstripping.
- The fire or ignition barrier over any foam, and whether it is in the price.
- Exclusions: mold remediation, abatement, drainage, electrical, drywall finishing, a dehumidifier.
A lower number that leaves out the sealing, the baffles or the barrier the code requires is not a cheaper version of the same job.
Is insulation worth the cost? What payback looks like
ENERGY STAR publishes two savings figures that do not agree. Its main seal-and-insulate page says sealing air leaks and adding insulation can save up to 10% on annual energy bills. The EPA modeling behind the program puts the average higher, at 15% of heating and cooling costs or 11% of total energy costs, and more in the north. We use the modeling, because it shows its method. For the climate zones we work in, it estimates 17% of heating and cooling costs (12% of the total bill) in zone 4, 16% (12%) in zone 5 and 18% (14%) in zone 6. The model is a typical house built between 1970 and 1989, sealed to cut air leakage by 25% and insulated to the 2012 energy code. A house that starts worse saves more; one already near code saves less.
Which zone are you in? In New Jersey, Bergen, Hunterdon, Morris, Passaic, Somerset, Sussex and Warren counties are zone 5 and the rest of the state zone 4. All of Connecticut is zone 5. In New York, Westchester, Nassau and Suffolk are zone 4, most of the Hudson Valley is zone 5, and Ulster and Sullivan counties are zone 6.
The Department of Energy measures it as simple payback: divide what the work costs by what it saves in a year, and the answer is the number of years to break even. Its Building America guide, published in 2012, warns that where insulation is already adequate you “may not save enough energy to recoup the cost,” while in a poorly insulated house or one with high heating and cooling bills, “added insulation is likely to pay for itself over time.” Its worked example, in 2011 dollars, is a 1970s tri-level in eastern Washington, where sealing and insulating the attic was estimated at $1,131 against $239 a year in savings: about five years. Prices have changed since, so borrow the method, not the dollars.
To estimate your own, add up last year’s energy bills, electric plus gas, oil or propane. Take your zone’s total-bill percentage (12% in zones 4 and 5, 14% in zone 6) as a rough guide to the yearly saving, and divide the price of the work by that figure. The same guide calls air sealing inexpensive and highly effective, and says that where a house has little or no insulation, especially in the attic, adding it is likely to pay for itself within a few years.
Savings vary. Find out why in the seller’s fact sheet on R-values. Higher R-values mean greater insulating power.
Rebates and tax credits
Utilities and state programs in New York, New Jersey and Connecticut pay incentives on insulation and air sealing; what you qualify for depends on your utility and the scope. Look before the work is booked, not after: rebates in New York and New Jersey and rebates in Connecticut. Leave the federal 25C credit out of the math, even where a cost guide still lists it: it does not apply to anything placed in service after 31 December 2025.
Common questions about insulation cost
How much does insulation cost?
Most of our projects run between $3,500 and $12,500. Nationally, HomeGuide (December 2025) puts installed insulation at $1.00 to $4.50 per square foot and an average house at $1,600 to $8,000. The job type sets the range: an attic floor top-up costs least, a sealed and lined crawl space or closed walls cost more. Area, access, the R-value target, air sealing, removal and fire barriers move it from there.
How much does it cost to insulate an attic?
HomeGuide (January 2026) puts attic insulation at $1 to $4 per square foot, $1,000 to $2,700 on average; Angi (December 2025) at $1 to $3 per square foot, $2,100 on average. Those are national averages, not quotes. The code’s ceiling target is R-49 under New Jersey’s 2024 IECC and New York’s 2025 energy code, and R-60 under the 2021 IECC Connecticut uses. Air sealing, vent baffles and removing damaged material add to the price.
How much does it cost to remove and replace attic insulation?
HomeGuide (November 2025) puts removal at $1 to $2 per square foot, and removal plus new insulation at $2 to $6 per square foot, $3,200 to $10,800 on average. Remove only what has to go: wet, rodent-soiled, fire-damaged or crushed insulation. Mold goes to a remediation company first. ENERGY STAR says insulation that is only dirty is still okay to use: seal the leaks under it and push it back. Then add depth if it is short.
How much does blown-in insulation cost per square foot?
HomeGuide (November 2025) lists $1.00 to $2.80 installed: cellulose $1.20 to $2.80, fiberglass $1.00 to $2.80, rock wool $1.90 to $4.20, and dense-pack cellulose in walls $1.60 to $4.20. Fixr (August 2025) averages $1.65 to $3.80. To check a quote, divide the attic area by 1,000 and multiply by the bags per 1,000 square feet that the bag’s chart gives for your R-value.
How much does crawl space encapsulation cost?
HomeGuide (January 2026) puts it at $3 to $10 per square foot, $3,000 to $15,000; This Old House (March 2026) at $5,500 on average, within $1,500 to $15,000. The spread is scope: a ground liner alone, or closed vents, a liner sealed to the walls, insulated walls and rim joists, and a drying method such as a dehumidifier. Drainage and repairs are extra.
How much does basement insulation cost?
HomeGuide (February 2026) gives $1 to $5 per square foot of the surface insulated, wall or ceiling, not of floor space; Angi (May 2026) gives $1.50 to $2.50 per square foot. Foam on the walls needs a thermal barrier such as drywall, and water has to be fixed before anything goes on. Sealing and insulating the rim joists is the smallest useful step.
How much does it cost to insulate existing walls?
HomeGuide’s wall guide (September 2025) gives $1 to $5 per square foot installed, $1,700 to $8,500 for the exterior walls of a 2,000-square-foot house; its blown-in guide (November 2025) puts blown-in walls at $1.10 to $3.70 per square foot. Closed walls get dense-pack cellulose or injection foam through drilled holes, so ask who closes the holes and matches the finish. ENERGY STAR says to fill empty wall cavities whenever the siding comes off.
How long does insulation take to pay for itself?
Divide the cost by the yearly savings. The EPA estimates that sealing and insulating a typical 1970s or 1980s house saves 16% to 18% of heating and cooling costs in the climate zones we work in. The Department of Energy’s 2012 guide gives an example in 2011 dollars: $1,131 of attic sealing and insulation saving $239 a year, about five years. A house that is already well insulated pays back slowly, if at all. Savings vary. Find out why in the seller’s fact sheet on R-values. Higher R-values mean greater insulating power.
Should an insulation quote be per square foot or per job?
Either works if it is itemized. For each area it should show the square footage and how it was measured, the material, R-value and depth, air sealing by location, removal, baffles and fixture dams, and any fire barrier. The FTC’s R-value Rule requires installers to give you a receipt with the coverage area, thickness and R-value, plus the bag count for loose fill.
Insulation prices in New Jersey, Connecticut, the Hudson Valley and Long Island
We price a house after going through it: what is in the attic and how deep, the crawl space or basement and any water, the walls, the wiring, and where air is getting through. You get a written scope with the area, material, R-value and air sealing for each part, and a straight answer on which parts are worth doing now and which can wait. That visit is our energy audit, and there is no charge for it.
Phone 914-825-6824, 8am–8pm, seven days a week, or send the contact form. The Home Insulators is a family-owned company, based in New Rochelle, NY since 2015, and every job is done by our own 100-plus-person crew; we never subcontract. We work in every county of New Jersey and Connecticut, in New York’s Hudson Valley and on Long Island (service area).