Home Projects · Startup costs
How much does attic insulation cost?
Half of US households who hired this job out paid under $2,741. That is Census data, not a contractor's average. Below, work out your own cost, and see the one number the insulation industry never puts in the pitch: how fast the savings run out as you add more.
Typical range $1,851 – $3,332
- Insulation material$1,039
- Installation labour$521
- Contractor overhead and profit$908
- Total$2,468
§ 02 The return
Cost per square foot is DOE's; applying it to your attic is our model, and DOE says its database is not intended to price a specific project. The payback is a standard degree-day calculation on EIA degree-days and BLS energy prices, and it ignores comfort, ice dams and a cooler upstairs bedroom, which are often the real reasons people do this. All figures in 2025 dollars.
Where the money goes
When it pays back
Cumulative cash flow. The line crosses zero the month your accumulated savings have repaid what you spent.
Recommended next steps
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A proper job. Get three quotes, and give each contractor the same depth measurement and the same target R-value, or you are comparing nothing at all. Ask each one whether air sealing is included, because it usually is not.
By the numbers
- Census (American Housing Survey, 2023): half of all contractor-hired insulation jobs cost less than $2,741, and half of do-it-yourself jobs less than $559. Hiring it out costs about five times as much as doing it. Blowing insulation is genuinely one of the easier jobs to do yourself: the machine comes free with the material at most big-box stores.
- The sample is small by this survey's standards (824 jobs, against 2,401 for roofing counted the same way), so we checked whether it holds up. It does: the relative standard error on the contractor median is 5.2%, which is tight. The one figure we would not lean on is the Northeast regional median, at 20.8%. We publish it, but with that health warning attached.
- DOE (REMDB): blown cellulose costs about $0.055 per square foot for each point of R-value you add, blown fibreglass about $0.071, and fibreglass batts about $0.056 plus a fixed premium that makes them the dearest option on any real attic. Cellulose is the cheapest way to buy an R-value, and it fills the awkward corners that batts bridge over.
- DOE's database records a service life of 999 years for attic insulation, which is its way of saying the stuff does not wear out. The same database gives windows 20 years. That difference is the whole argument, and it is why we are happy to recommend this job and not that one: a 12-year payback on something that never needs replacing leaves you decades of free heat, while a 20-year payback on a window DOE expects to last 20 years is not a trade at all. It is a wash, and then you buy the window again.
- EPA (ENERGY STAR): homeowners save an average of 15% on heating and cooling costs, or 11% on total energy costs, by air sealing AND adding insulation. Read that again. The 15% figure that gets quoted at you for an attic job is EPA's estimate for air sealing PLUS insulating attics PLUS floors over crawl spaces PLUS accessible basement rim joists. It is a figure for the whole package, routinely quoted for one part of it.
- The 2022 Economic Census says insulation and drywall contractors take in $152.88 for every hour their field crews work, while paying those crews $30.01 an hour. That 5.09x is not a scandal, it is what carries the truck, the insurance and the estimator. It is worth knowing before you read a quote, and it is worth knowing that about a third of your bill is it.
What is sourced here, and what is ours. The headline is sourced: the Census American Housing Survey asks households what a completed job actually cost, and JOBTYPE 20 ("added or replaced insulation") gives a median of $2,741 hired out and $559 done yourself, across 824 real jobs. We did not model that, we counted it. What is ours is the build-up: applying DOE's per-square-foot cost curve to your attic area and R-value, and the payback, which is a standard degree-day heat-loss calculation using EIA degree-days and BLS energy prices. DOE states its cost database "is not intended to provide specific cost estimates for a specific project," so treat your total as a well-founded estimate, not a quote. One reassurance: the two rarely agree this closely. Our build-up for a typical job lands at $2,468, within 10% of what Census says people actually paid. On our window page the same kind of build-up came out at about two and a half times the real-world median, and we said so there too.
Sources: US Census Bureau / HUD, American Housing Survey 2023 (what households actually paid) · DOE/NREL National Residential Efficiency Measures Database (installed cost by R-value) · EPA ENERGY STAR, Methodology for Estimated Energy Savings (the 15% figure, in context) · US Census Bureau, 2022 Economic Census (what the trade bills per field hour) · EIA Monthly Energy Review, degree-days by census division · BEA price index for residential improvements, used to bring older dollars to 2025
How this estimate is calculated
- The headline medians are not modelled. They are what 824 US households told the Census they actually paid for a completed insulation job, deflated from their own completion year to 2025 dollars with the BEA price index for residential improvements.
- Your cost is DOE's installed cost per square foot at the R-value you are ADDING, not the R-value you are aiming for. If you have R-19 and want R-49, you are buying and installing R-30 of new material, and that is what we charge you for.
- DOE's installed cost already includes the contractor's overhead and profit. We checked this rather than assuming it: divide DOE's total by DOE's own labour hours and you get $161 per field hour, and the 2022 Economic Census independently measures $168 per field hour for the trade. They agree to within 4%, so we add no markup on top. Had we assumed the DOE figure was a bare cost and applied the trade's measured 5.09x markup, this page would have quoted you roughly three times too much.
- The energy saving is a degree-day calculation: area, multiplied by the change in 1/R, multiplied by your region's heating and cooling degree-days from EIA. It uses 2025 average US energy prices from BLS, an 80% furnace, a heat pump at a seasonal COP of 2.5, and a SEER-14 air conditioner.
- The payback has error bars in BOTH directions, and we would rather show you them than pretend the model is a quote. It pushes the saving UP by counting only the R-value of the insulation, ignoring the R-2 or so the plasterboard and the air films are already worth, and by treating your attic as if it were as cold as the outdoors, which a vented attic is not quite. It pushes the saving DOWN by ignoring the heat an attic picks up from the sun, so cooling savings are understated in hot climates. On balance, read the payback years as an optimistic central estimate: if your ceiling is nearer R-13 than the R-11 you picked, the default job pays back nearer 15 years than 12. What none of that touches is the finding on this page, because the bare-attic and top-up jobs are run through exactly the same formula, and it is the RATIO between them, not the absolute year count, that decides whether a quote is worth taking.
- AHS records one cost per job and no scope at all. Insulating a rim joist and blowing R-49 across a whole attic are both JOBTYPE 20, and the survey does not even say which part of the house the insulation went into. So it can tell you what people paid, and it can never tell you a price per square foot. Anyone quoting you an AHS-derived cost per square foot has invented it.
- Air sealing is priced from 466 real completed projects in DOE's database, at a median of $697. We charge you for it but credit it with no savings at all, because no free source isolates what air sealing alone saves. Ticking that box therefore makes the payback look worse than the truth. That is us refusing to guess, not evidence against air sealing, which is usually the best dollar you can spend up there.
- The low-to-high range is plus or minus a quarter to a third, reflecting how much regional pricing and attic access move a real quote. A cramped attic with a hatch in a wardrobe costs more than a walk-up with a floor.