Attic Insulation Cost
Per Square Foot

Insulation Comparison – Cost & Performance



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Cost to insulate
an attic R-49 in per 1000 sq ft

Planning a home improvement project includes insulation for sound, temperature, and moisture. Insulation budget considerations should include cost/value ratio and measure performance

R49 is the minimum code for attics in zone 5 which includes parts of the Midwest and Chicago.

R38-R49 loosefill fiberglass for example, does not perform well in extreme heat (summer days in Chicago averaging 85-90 degrees) or extreme cold -10 30 degrees ), while spray foam, mineral wool, or loose fill cellulose are all options for the attic floor. 

This includes air seal, baffles, and hatch cover. 

insulation cost r value cost per inch insulation contractor chicago spray foam cost vs cellulose vs fiberglass comparison insulator contrator sprayfoam

Cellulose Attic Insulation
Costs Per Sq Foot Calculator

Cost for cellulose insulation include

  • Attic insulation – $2.30 Per Sq. Ft.
  • Cathedral ceiling insulation –  $3.50 – 5.00 Per Sq. Ft. 
  • Flat roof insulation –  $3.50 – 5.00 Per Sq. Ft.
  • Basement insulation – $1.50 – 4.00 Per Sq. Ft.
  • The exterior wall insulation – $1.50 – 4.50 Per Sq. Ft.
  • Garage ceiling insulation – $3.50 – 5.00 Per Sq. Ft.
  • Transition wall insulation – $2.50 – 4.00 Per Sq. Ft.
  • Furnace room insulation – $1.50 – 4.00 Per Sq. Ft.
  • Crawl space insulation – $2.50 – 4.50 Per Sq. Ft.
  • Kitchen and bathroom wall insulation – $1.50 – 4.50 Per Sq. Ft.

*Prices are based on the current average cost and may vary based on the scope of work.* 

Cellulose loose-fill insulation has a major advantage over batt or spray foam powerful truck-mounted blowing machines blown directly into the stud cavity with the drywall already in place.

Advantages:  A cost-effective alternative to spray foam when retrofitting building or residential homes. Cellulose is plant-based recycled materials.

Disadvantages: Thermal Bridging

Advantages: Cost. Green Materials. Non-itch.

Home insulation cost
per sq ft


Insulation materials are produced in a variety of ways using several different material combinations. 

Why start with the attic?

Achieving results such as comfortable stable home interior temperatures with the desired amount of humidity / dry air.  By reaching the recommended home insulation R-Values through thermal performance or R-value of insulation is dependent on proper installation of that material and its interaction with surrounding materials. Comparing insulation cost for 2×6 sidewalls, attic insulation, cathedral ceilings, and basement insulation, we find cellulose is preferred with exception of basement wall insulation. 

Since R-Value is measured in enclosed spaces, any air infiltration into the insulated cavity significantly reduces the intended R-Value.

We install the correct/optimal insulation levels for your attic R60, ceilingR38-60, sidewall R21, basement R13, and crawl space R13-38.  

Your budget $3 per sq ft for insulation which includes additional considerations. Fire stop and air seal cost an extra .35 cents. Cellulose provides R21 insulation, fills voids and gaps left by fiberglass, performs better in summer, and has better fire resistance, mold mildew and moisture resistance, and is pest resistant. 

  • Insulation labor and material
  • Fire stop 
  • Air seal
  • R-value to code
  • Proper ventilation
  • Cozy comfortable interior
  • Pass occupancy inspections

Attic Insulation Cost
Advantages / Disadvantages

Insulation cost factors measured by R-Value as a key performance indicator.  

Spray foam is superior in R-value per inch, making it ideal to choose a combination of closed cell spray foam as the bottom layer and fiberglass batts to fill in the depth of the framing cavity (called the flash and batt method.)

Flash and Batt Method is a new hybrid combination of closed cell spray foam and fiberglass batts to reduce costs of labor and materials for spray foam insulation.

Areas to Choose Cellulose Over Spray Foam include

Spray Foam
Insulation Cost

Spray foam insulation cost- spray foam is currently 1.65 per inch. but how many inches are you installing .  3 ” of foam vs 16 inches of cellulose you will get greater heat retention . R60 vs R21 rating for an enclosed space. 


Cost per inch of R-Value for an existing cathedral ceiling. Four Considerations are fiberglass batt, loose fill fiberglass, loose fill cellulose, and closed cell spray foam. Cost per inch includes labor, material, installation. 

What is the cost of spray foam ? spray foam in a cathedral ceiling vs 6″ of cellulose. $4.50 R35 with spray foam (benefit more tight . but if you seal the gaps properly with tyvek seam tape . with cellulose gives about R21. $2

if you open the ceiling to spray cost of drywall removal and drywall replaced after spray. 

what is the cost of cellulose? 

Fiberglass is rarely used
except in basement walls.

Green Attic applies spray foam to cathedral ceiling roof rafters, rim joists, and crawl space and basement walls most commonly.  Cellulose insulation is used for garage ceilings, exterior and interior walls and ceilings for sound and thermal protection, and attic floors for optimal heat resistance. Fiberglass is rarely used except in basement walls with the paper side facing out towards the living space as a vapor barrier.

wall insulation 2×6 cellulose stops air 35 % better than fiberglass. its fire retardant and doesnt require drywall removal for insulation . gaps and cracks in older home lower r value per inch than spray foam . cellulose is cost efficient . lower r value on a 2×4.  for the wintertime fiberglass is great because the drywall holds the heat in the room . in the summer time the fiberglass is letting the heat pass through and making the drywall hot. 

Basement Insulation
Mind the Moisture Barrier

To choose the best type of insulation, you should first determine the following:

  • Who will diagnose the current conditions of the home based on occupants experience with cold or drafty rooms in the winter and hot / humid 2nd floor bedrooms  and create an action plan for change? will install the insulation
  • What  is the reason for choosing to add insulation / ventilation to your attic, exterior  walls, garage ceiling, basement, or crawlspace and what are the recommended R-values for areas you want to insulate.
  • Where  you want improvements on the interior living space ( home )  install/add insulation
  • Why  types of insulation Cost Per Inch Vs. R-Value

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If you are looking for a company that couples outstanding work with outstanding customer service, then Green Attic Insulation is who you should definitely call. I truly wish I would have called them years ago as I have been putting off suspected issues that centered around extreme temperature fluctuations between winter and summer, along with poor ventilation, within my attic.

Theo James

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James is prompt, thorough, and personable -- responded to my website inquiry right away and made it easy to schedule an appointment (still haven't heard back from the competition -- that was three days ago). He provided a detailed and professional quote within minutes of being on site and saved me from spending $20k on an unnecessary new roof! I'm glad I contacted Green Attic.

Emilia Munro

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Highly recommend! Green Attic is thorough, responsive, and professional. Although it has only been a month since we had the work done, the results are clear. Our house is more comfortable, while our gas consumption is down ~30% and electricity is down ~25%.

Branden Griffiths

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