Attic Insulation Cost (2026): $4,556 to $7,009
What a contractor's cost is in 2026 to air seal and insulate an attic, dense pack walls, and insulate a rim joist, basement and floors: R-values by climate zone, what air sealing adds, and where the hours are.
The assumptions
This model assumes
- Attic 1,200 sq ft, walls 1,500 sq ft, rim joist 120 ft unless stated
- Job cost before markup: labor, sub prices and materials, no tax
- National prices with no regional adjustment
- Hours are Clamp's own labor lines; sub lines carry none
- Prices from Clamp's catalog on November 11, 2026
The model, step by step
Priced through Clamp's catalog on November 11, 2026 for a 1,200 sq ft attic. Every price in this guide is job cost before markup: what the labor, the insulation sub and the materials cost you. These are national prices with no regional adjustment. Hours are Clamp's own labor lines only; the blowing is a sub's price and carries no hours (see step 7).
Attic at the eave
Drawn for this guide in the style of Quick Clamp's sketch pad: the attic at the eave. The pad has no insulation tool, so this is an illustration with typed labels. Demo data.
| Attic job | Job cost | Hours |
|---|---|---|
| Top up R-19 to R-38Air seal, baffles, blown | $2,616 | 29 |
| Top up R-19 to R-49Air seal, baffles, blown | $3,060 | 29 |
| Top up R-19 to R-60Air seal, baffles, blown | $3,505 | 29 |
| Top up, no air sealingR-19 to R-49, baffles and blown | $1,650 | 5 |
| Empty attic to R-49Air seal, baffles, blown | $3,828 | 29 |
| Empty attic to R-60Air seal, baffles, blown | $4,272 | 29 |
| Remove old, blow R-49Vacuum out, haul, air seal | $5,238 | 45 |
| Batts to R-49Two cross-laid layers | $4,488 | 29 |
| Foam the rooflineOpen cell, unvented attic | $5,466 | 1 |
Two national references set the target. ENERGY STAR publishes retrofit levels by climate zone. The 2021 International Energy Conservation Code sets the minimum ceiling insulation for new work. Your state may be on an older edition with lower numbers, so check what is adopted where you work.
| Zone | Empty | 3-4 in | Code |
|---|---|---|---|
| 1ENERGY STAR, then the 2021 code | R-30 | R-25 | R-30 |
| 2 and 3ENERGY STAR, then the 2021 code | R-49 | R-38 | R-49 |
| 4 to 8ENERGY STAR, then the 2021 code | R-60 | R-49 | R-60 |
Reading the table on a retrofit
A top-up is an alterationThe energy code's alteration rules do not require wall cavities you have not exposed to be filled. How an attic top-up fits is the code official's call.
Depth depends on the productOne cellulose is 14.3 in blown and 13.3 in settled for R-49. One loose-fill fiberglass is 17 in for R-49. Use the chart on the bag you are blowing.
Bags per 1,000 sq ft at R-49About 71 bags of that 25 lb cellulose, or 25 bags of that fiberglass. Order whole bags from the chart, not from an R-per-inch rule.
Topping upOver R-19 you are adding R-41 to reach R-60, not R-60. Clamp prices the added R-value: $1,657 of blown insulation on this attic.
Insulation over an unsealed ceiling leaves the air leaks in place. On this attic Clamp carries $1,410 and 24 person-hours for air sealing, close to the $1,657 for the blown insulation itself.
What the air sealing line covers
SealTop plates, wiring and plumbing holes, open chases, dropped soffits and the attic hatch.
Recessed lightsKeep insulation 3 in from lights that are not rated for insulation contact. A box built around one is fire-rated board with the same 3 in of clearance, and its top stays uncovered.
FluesSheet metal and high-temperature sealant, and a dam that holds insulation off the flue. Sealant does not replace the flue's clearance.
EavesA baffle in each vented rafter bay keeps the soffit vent open and lets the insulation run out over the wall plate.
VentilationThe residential code calls for vent area of 1 to 150 of the attic floor, or 1 to 300 under its conditions: 8 sq ft, or 4, on this attic.
Combustion safetyA tighter house can backdraft a furnace or water heater. Have combustion appliances tested as part of the work.
Priced for 1,500 sq ft of empty wall. From outside, a course of siding comes off, each bay is drilled and filled, and the siding goes back. From inside, the drywall is drilled, plugged and painted.
Wall from outside
Drawn for this guide in the style of Quick Clamp's sketch pad: a wall filled from outside. The pad has no fill-hole tool, so this is an illustration with typed labels. Demo data.
| Walls | Job cost | Hours |
|---|---|---|
| Outside, vinyl sidingCourse pulled and reset | $7,095 | 61 |
| Outside, wood sidingCourse pulled and reset | $6,780 | 55 |
| Outside, aluminumSlower to pull and reset | $8,040 | 79 |
| Inside, patch and paintDrill, plug, repaint | $7,323 | 65 |
| Inside, patch onlyDrill and plug | $5,970 | 49 |
Before you drill
DensityDense pack is at least 3.5 lb per cu ft. Check the bag count against the wall area; a loosely filled bay settles.
Knob-and-tubeThe National Electrical Code does not allow insulation packed around knob-and-tube wiring. Some states amend that: Washington allows loose or rolled insulation, not foam, after a licensed electrician certifies the wiring.
Clamp runs high hereThe same program schedule pays $2.88 to $3.59 per sq ft for 4 in of dense pack in a wood, vinyl or aluminum sided wall. Clamp is $4.52 to $5.36.
The rim joist is the short job: about 4 hours of your labor on 120 ft. Basement walls and floors are priced by the method.
Rim joist
Drawn for this guide in the style of Quick Clamp's sketch pad: one rim joist bay in section. The pad has no foam tool, so this is an illustration with typed labels. Demo data.
| Job | Job cost | Hours |
|---|---|---|
| Rim joist, 2 in foam120 ft, closed cell | $858 | 4 |
| Rim joist, rigid foam120 ft, cut and sealed | $559 | 4 |
| Basement, foam and studs130 ft of wall, 8 ft high | $9,768 | 47 |
| Basement, foam on furring130 ft of wall, 8 ft high | $7,129 | 42 |
| Floor over a garage1,000 sq ft, batts | $1,895 | 1 |
| Floor over a crawlspace1,000 sq ft, batts | $2,635 | 1 |
| Crawlspace, encapsulate800 sq ft | $3,075 | 24 |
Foam and concrete
Foam needs coverMost codes require a thermal barrier, typically half-inch drywall, over foam insulation. Some products are tested to go without one in a rim joist or a service-only space. Read the product's code report.
Basement wallsPut rigid foam against the concrete and leave out the interior plastic vapor barrier. Fiberglass batts against the concrete take on moisture.
Spray foam minimumsA spray foam sub often has a minimum charge that a 120 ft rim joist does not reach. Clamp does not price one.
FloorsBatts under a floor normally go in full contact with the subfloor and are held there with supports.
Checked on November 11, 2026.
What to know before you quote
VermiculiteEPA says to assume vermiculite attic insulation may contain asbestos and to leave it undisturbed. Do not blow over it or vacuum it out yourself.
Vermiculite moneyA trust reimburses part of the cost of removing Zonolite brand vermiculite. On October 7, 2026 it cut its payment from 55% of the allowed cost to about 36%. A claim filed by November 30, 2026 keeps the 55% only if the removal and the paperwork are finished by January 31, 2027. Send the owner to the trust.
Federal tax creditThe energy efficient home improvement credit (Section 25C of the tax code) does not apply to anything placed in service after December 31, 2025. A 2026 insulation job gets no federal tax credit.
RebatesFederal home energy rebates are run state by state, and not every state has opened. Under the electric home rebate program, insulation, air sealing and ventilation share one $1,600 cap, with income limits. The whole-house savings rebate works differently. Check your state's program before you take anything off a price.
Clamp prices blown insulation, dense pack, batts and spray foam as an insulation sub's all-in price per square foot, so those lines carry no hours. The hours in this guide are the work around it: air sealing, baffles, pulling siding, removal and protection.
Published crew output for the sub's part
Blowing an atticOne cost guide gives 7.5 to 8.5 labor hours per 1,000 sq ft at R-38 and 10 to 11 at R-49.
Air sealingThe 2007 report put a standard job at 8 to 16 man-hours. Clamp: 24 on this attic.
Dense packNo published production rate was found. Clamp's 55 hours of siding work on 1,500 sq ft is two people for about three and a half days.
A two-story house in climate zone 5 has a 1,200 sq ft attic with R-19 of old fiberglass, empty 2x4 walls behind wood siding, and a bare rim joist. Scope A air seals the attic and blows to R-60: $3,505. Scope B adds 2 in of closed-cell foam on 120 ft of rim joist: $4,363. Scope C adds dense pack in 1,500 sq ft of wall from outside: $11,098.
| Line | Job cost | Hours |
|---|---|---|
| Blown insulation to R-601200 sf | $1,657 | |
| Air seal the attic floor1200 sf | $1,140 | 24.0 |
| 2 in closed-cell foam180 sf | $510 | |
| Eave baffles35 ea | $280 | 3.5 |
| Foam, caulk and sealant0.6 ls | $270 | |
| Seal the rim joist120 lf | $210 | 3.8 |
| Consumables1 ls | $125 | |
| Dam at the hatch, materials1 ea | $75 | |
| Site protection1 ea | $45 | 0.8 |
| Dam at the hatch, labor1 ea | $38 | 0.5 |
| Fasteners12 lf | $13 |
The job
Every line priced
The job in Clamp, and the estimate it prices: $4,363 at job cost, by trade. Recreations of the Clamp app with demo data.
What it means
Every insulation job, line by line
Clamp reads the attic size, the R-value in place and the target, the material, the siding and the feet of rim joist from the words, and prices the air sealing, baffles, insulation and access as separate lines.
The insulation is the cheap part. The air sealing and the access are the job.
Questions
How much does attic insulation cost?
In Clamp's catalog a 1,200 sq ft attic with R-19 in place costs $3,060 to air seal and blow to R-49 and $3,505 to R-60, in job cost before markup. Blown insulation with baffles and a hatch dam, and no air sealing, is $1,650. The ballpark price range to R-60 is $4,556 to $7,009.
How much does blown-in wall insulation cost?
Dense pack in 1,500 sq ft of closed wall is $6,780 to $8,040 from outside, by siding type, and $7,323 from inside with the holes patched and painted, in job cost before markup. One utility-sponsored program's 2024 schedule pays less: $2.88 to $3.59 per sq ft of wall.
How much does rim joist insulation cost?
For 120 ft of rim joist, Clamp's catalog prices 2 in of closed-cell spray foam at $858 and cut rigid foam sealed with can foam at $559, in job cost before markup. A spray foam sub often has a minimum charge that a job this size does not reach.
What R-value should an attic have?
ENERGY STAR recommends R-60 for an uninsulated attic in climate zones 4 to 8 and R-49 in zones 2 and 3. With 3 to 4 inches already there, it recommends R-49 and R-38. The 2021 energy code uses the same R-49 and R-60 for new ceilings, and states on older editions require less.
Is there a tax credit for insulation in 2026?
No. The IRS says the energy efficient home improvement credit (Section 25C) does not apply to property placed in service after December 31, 2025. State-run rebates exist in some states; check your state's program.
Sources & provenance
- Clamp's catalog, priced by script Clamp (research)
- Recommended home insulation R-values ENERGY STAR (official source)
- 2009 to 2021 IECC and IRC minimum insulation requirements for new homes Pacific Northwest National Laboratory (official source)
- Sealing and insulating existing exterior walls: code compliance brief Pacific Northwest National Laboratory (official source)
- SANCTUARY blow-in cellulose coverage chart Greenfiber (research)
- AttiCat expanding blown-in insulation fact sheet Owens Corning (research)
- Attic air sealing project ENERGY STAR (official source)
- Seal and dam around non-IC recessed lights US Department of Energy (official source)
- Seal around chimneys and flues US Department of Energy (official source)
- Code change proposal for IRC R806, roof ventilation (quotes the code's vent area text) International Code Council (official source)
- Combustion appliance zone (CAZ) testing Pacific Northwest National Laboratory (official source)
- Blown insulation for cavities of existing exterior walls Pacific Northwest National Laboratory (official source)
- BSD-103: Understanding basements Building Science Corporation (research)
- Protect your family from asbestos-contaminated vermiculite insulation US Environmental Protection Agency (official source)
- ZAI Trust FAQs ZAI Trust (research)
- WAC 296-46B-394, knob-and-tube wiring Washington State Legislature (official source)
- FAQs for modification of sections 25C, 25D, 25E, 30C, 30D, 45L, 45W and 179D under Public Law 119-21 IRS (official source)
- Home energy rebates frequently asked questions US Department of Energy (official source)
- Contractor pricing strategies for air sealing attics in existing homes ICF International for ENERGY STAR (official source)
- Blown-in insulation cost HomeGuide (research)
- Schedule of unit prices, 2024 CLEAResult (lead vendor, Mass Save Home Energy Services) (research)
- Rigid foam board interior insulation for existing foundation walls Pacific Northwest National Laboratory (official source)