Ashburn, VA

How much does attic insulation cost?

$1 – $4 cost per square foot installed
$1,000 – $2,700 average total cost to install

Get free estimates from insulation contractors near you, or view our cost guide below.

March 15, 2022

Reviewed by Tom Grupa and 3 expert insulation contractors on HomeGuide.

Attic insulation cost

Attic insulation costs $1 to $4 per square foot installed, depending on the type, R-value, job size, and complexity. The average cost to insulate an attic is $1,000 to $2,700. Small attic insulation costs start at $500, while insulating large attics costs up to $6,000.

Attic insulation cost
Attic size (square feet) Average cost installed
500 $500 – $2,000
700 $700 – $2,800
1,000 $1,000 – $4,000
1,200 $1,200 – $4,800
1,500 $1,500 – $6,000
2,000 $2,000 – $8,000

Some insulation companies have a $1,500 to $2,000 minimum project requirement.


Average cost to insulate an attic

The following table shows the average cost to insulate an attic.

Average attic insulation cost
Average attic insulation cost

Average cost to insulate an attic
National average cost $1,800
Minimum cost $500
Maximum cost $6,000
Average cost range $1,000 to $2,700

Cost data is from research and project costs reported by HomeGuide members.

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Attic insulation cost calculator by type

Attic insulation costs range from $1,000 to $6,800 or more installed, depending on the type and job size:

Attic insulation cost calculator
Type Average cost (per square foot) Average installed cost*
Batt and roll insulation $0.80 – $2.60 $1,100 – $3,900
Blown-in insulation $0.90 – $2.40 $900 – $3,600
Loose-fill insulation $1.00 – $2.50 $1,100 – $3,800
Spray foam insulation $1.00 – $4.50 $1,100 – $9,000
Reflective insulation $0.50 – $2.20 $550 – $3,300
Structural insulation panels $4.00 – $12.00 $4,400 – $12,000+

*Based on a 1,100 to 1,500 square foot attic floor.

Contractor insulating attic floor with batts and rolls
Contractor insulating attic floor with batts and rolls

Blown-in attic insulation cost

Blown-in insulation costs $900 to $3,600 on average or $0.90 to $2.40 per square foot, depending on the attic size, R-value, and the amount of fixture damming and air sealing needed. Blown-in attic insulation is ideal for most attics because it effectively fills gaps and irregularly shaped areas.

Attic spray foam insulation cost

Attic spray foam insulation costs $1.00 to $4.50 per square foot or $0.60 to $2.90 per board foot, depending on the type, R-value, and job size. Attic spray foam insulation costs $1,100 to $6,800 on average for the floor and $1,500 to $9,000 for the rafters and roof deck.

Attic spray foam insulation cost
Location Average cost installed
Attic floor $1,100 – $6,800
Attic rafters / roof deck $1,500 – $9,000
  • Open-cell foam works well in vented attics to fill nooks and crannies on the attic floor. Open-cell foam provides an air barrier, but some applications may require a vapor barrier.
  • Closed-cell foam works best for roof decks in unvented attics. Closed-cell foam provides an air, moisture, and vapor barrier.

Batt and rolled attic insulation cost

Batt and rolled attic insulation costs $0.80 to $2.60 per square foot installed or $1,100 to $3,900 on average. Complete replacement of attic batts may cost up to $4.70 per square foot to achieve the recommended R-value. Batt and roll insulation works best with standard framing and minimal obstructions.

Structural insulated panels prices (SIPs)

Structural insulated panels (SIPs) cost $4 to $12 per square foot for the material alone, depending on the thickness. SIPs are large panels – 4' x 8' up to 8' x 24' – primarily used in new construction but sometimes installed at the rafters when converting an attic to a conditioned space.

  • An SIP consists of a rigid foam insulation center with a layer of plywood or oriented strand board (OSB) on each side.
  • SIPs have excellent R-value, soundproofing, and waterproofing properties.

Loose-fill attic insulation cost

Loose-fill attic insulation costs $1.00 to $2.50 per square foot installed on average. Loose-fill insulation is the same material as blown-in, but the labor cost is slightly higher to install.

Loose-fill works best for:

  • For obstructed or complex spaces
  • For attics with irregular joist spacing
  • For topping over existing insulation or filling gaps

Reflective insulation prices

Reflective insulation costs $0.50 to $2.20 per square foot installed. Reflective insulation is a radiant barrier attached to a thin thermal layer that provides an R-value of R-3 to R-21 when combined with dead air space during installation.

Reflective insulation is best when paired with other insulation types to increase the R-value and block all forms of heat transfer.

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Cost factors to install or replace attic insulation

Replacing attic insulation costs $2 to $6 per square foot, including $1 to $2 per square foot to remove the old insulation. Additional costs may be required for air sealing or encapsulating, cleaning, or making repairs in the attic:

  • Labor – Insulation labor costs $0.50 to $1.30 per square foot, depending on the material, R-value, conditions, and sealing and venting requirements.
  • CleaningAttic cleaning costs $100 to $500+. Costs increase when removing old insulation, relocating items, or addressing mold or pest issues.
  • Home age – Older homes typically require more insulation and sealing.
  • Size – Larger attics require more material and labor. The cost per square foot may decrease on large-scale projects.
  • Accessibility – High-pitched roofs or irregularly-shaped, hard-to-reach spaces requires more labor.
  • Existing insulation – The current insulation condition impacts the insulation amount needed. Damaged insulation may require removal and replacement.
  • Vented vs. unvented space – Most homeowners insulate at the roof deck in an unvented attic. The roof's larger surface area requires more labor and material than the attic floor.
  • Faced vs. unfaced – Faced insulation costs slightly more and is typically used for first-time applications. Use unfaced material when increasing the attic insulation.
  • R-value – Homes in colder regions require a higher R-value, which increases the required thickness and cost.
  • Installing baffles at the soffit vents costs $2 to $3 per baffle and is essential to prevent the insulation from blocking airflow.
  • Roof vent installation costs $200 to $700. Vents exhausting into the attic must be vented outside before installing new insulation.
  • Roof leak repairs cost $500 to $1,200 on average.
  • Electricians charge $40 to $100 per hour to repair damaged wiring.
  • A pest inspection costs $40 to $150 and is recommended before insulating an attic.
  • Attic mold removal costs $1,500 to $3,500+.
  • Asbestos removal costs $20 to $65 per square foot. Asbestos testing costs $250 to $750.
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Attic insulation removal cost

Attic insulation removal costs $1 to $2 per square foot on average, depending on the amount and type. Remove old insulation if it has fire, water, or pest damage or if the material is hazardous. Removing insulation also exposes the area to seal all penetrations.

Attic insulation material prices

Attic insulation material prices are $0.30 to $12.00 per square foot. The Department of Energy recommends R-30 to R-60, depending on the climate zone. Combining a thin spray foam layer with blown-in or batt insulation reduces the cost to air seal and achieve the desired R-value.

Attic insulation material prices
Material R-value per inch Material cost per square foot
Cellulose 3.1 – 3.8 $1.20 – $2.50
Fiberglass 2.2 – 2.9 $0.30 – $1.30
Rockwool / mineral wool 3.2 – 4.1 $0.30 – $1.80
Reflective insulation 1.3 – 1.6 $0.30 – $0.80
Structural insulated panels (SIPs) 4.0 – 5.0 $4.00 – $12.00
Closed-cell spray polyurethane foam 5.0 – 7.0 $0.90 – $1.00 per board foot
Open-cell spray polyurethane foam 3.5 – 3.7 $0.30 – $0.50 per board foot
  • A board foot is a square foot with 1" thickness.
  • Fiberglass, cellulose, and Rockwool may be blown-in, loose-fill, or batt and roll.

Cost to air seal or encapsulate an attic

  • Air sealing an attic costs $350 to $3,000, depending on the ductwork, gaps, and ceiling fixture penetrations. Air sealing the floor in a vented attic is essential for effective insulation. Some contractors include air sealing in an attic insulation estimate.
  • Attic encapsulation insulates the underside of the roof deck and seals all attic vents, making the attic a conditioned part of the home. Consider encapsulation if the attic contains HVAC equipment, ductwork, or stored items or when sealing the attic floor is too labor-intensive.

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Cost to add more insulation to an attic

Adding more insulation to an attic costs $1 to $4 per square foot professionally installed, depending on the existing insulation, desired R-value, and type. Adding 5 inches of loose-fill insulation yourself costs $200 to $650 to cover 1,000 square feet.

The new insulation does not need to be the same type as the existing insulation.

Do not compress the insulation batts when adding or installing insulation. Compression reduces the air pockets and lowers the material's R-value.

Attic insulation FAQs

Can I install attic insulation DIY?

Installing attic insulation is DIY-friendly when adding batts, blown-in, or loose-fill insulation. Hire a certified professional to install spray foam insulation because it requires mixing dangerous chemicals.

Before installing attic insulation DIY:

  • Seal all air leaks and penetrations.
  • Add a vapor barrier if your region requires it.
  • Add ventilation if needed. Add baffles to prevent soffit vent blockage.

How much will I save by adding attic insulation?

Adding attic insulation saves 10% to 20% on heating and cooling costs, depending on the climate and existing insulation. Improving the home's attic insulation and energy efficiency typically pays for itself in 3 to 5 years with lower energy bills.

A home energy audit helps determine the most beneficial sealing and insulation updates.

How long does attic insulation last?

Attic insulation lasts 20 to 100 years, depending on the type and the attic conditions:

  • Fiberglass insulation lasts 80 to 100 years in perfect conditions. Check the insulation after 15 to 20 years to confirm the R-value is still up to code.
  • Cellulose insulation lasts 20 to 30 years and starts degrading around the 15-year mark.
  • Spray foam insulation lasts 80 years or more on the attic floor if properly installed and undisturbed, and up to 30 years on the roof deck underside.

What is the best type of insulation for an attic?

Spray foam insulation performs the best in attics but is the most expensive. Fiberglass batts and blown-in cellulose are the most common in attics but are less effective.

How many inches thick of insulation in an attic?

Energy Star recommends insulating to R-38 or 10 to 14 inches thick in most attics. Colder climates require R-49 to R-60.

Insulation R-value recommendations
Insulation R-value recommendations

Under-insulating leads to higher energy costs and reduced indoor comfort. Over-insulating results in a poor return on investment and may impact the attic ventilation, increasing moisture and mold potential.

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Getting attic insulation estimates and quotes

Before hiring an insulation company:

  • Get at least three quotes to compare.
  • Ask for a firm, itemized bid.
  • Look for professionals experienced in attic insulation.
  • Browse their reviews on HomeGuide and Google.
  • Select insured and bonded companies that have been in business for more than five years.
  • Ask for references.
  • Avoid selecting the lowest quote as quality may suffer.
  • Get a detailed estimate, contract, and warranty in writing before the work begins.
  • Never pay in full before the project starts. Use a payment plan instead for work completed.

Questions to ask attic insulation companies

  • Are you licensed, bonded, and insured?
  • How long have you been in business?
  • What experience do you have with attic insulation?
  • What type of insulation do you recommend for my attic, and why?
  • Is air sealing included in the estimate?
  • How much can I expect to save on utilities after installation?
  • Is removing damaged or old insulation included in the quote?
  • Do you offer financing options?
  • Can I be in the house during the insulation process?
  • How long will the project take?
  • How long should the insulation last?
  • Is there a warranty, and if so, what does it include?
  • What is and is not included in the price?
  • What additional costs should I expect?
  • Are there rebates available, and do you apply for them?

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