$0.30 – $0.40 cents / sqft
Average Cost Estimate
$0.45 – $0.60 cents / sqft
$0.55 – $0.95 cents / sqft
|Insulation Type||Cellulose Bags||Cellulose Bags||Cellulose Bags|
|Amount Needed||9-14 Inches||11-18 Inches||14-18 Inches|
|Ease of Access||Average||Average||Average to Hard|
|Prep Work Required||Minimal||Average||Average to High|
|Cost of Tools & Supplies||$50 – $75||None / Included||None / Included|
|Permits, If Required||$0||$0||$0|
Adding attic insulation has the highest return on investment of any home improvement project, according to a respected annual building industry survey. The most recent data shows that attic insulation raises home sale prices by 107% of its cost. If you don’t sell, attic insulation quickly pays for itself through lower energy bills.
How much insulation does your attic need? R-value, or resistance value, is a measurement of how resistant material is to heat transfer. The higher the R-value, the better the insulation value. The US Department of Energy’s Energy Star program details the R-values recommended for each climate zone in the US.
The recommended R-values are:
If there is already some insulation in your attic, measuring it will help determine its R-value. Also check our spray on insulation estimates to get an idea of those costs. Fiberglass insulation has a value of R2.2 to R2.7 per inch. Cellulose insulation’s value is R3.2 to R3.8 per inch, or an average of R3.5 per inch of thickness. It’s OK to mix insulation types, for example, using blown cellulose over fiberglass batts. However, if the old insulation is wet or shows signs of mold, it should be removed. Of course, wet or moldy insulation indicates a roof leak or poor attic ventilation, issues that should be resolved before adding fresh insulation.
In this Costimate, we’ll help you estimate the costs for insulating your home with blown-in insulation. You’ll learn how much you need, how to measure the current r-value, as well as estimating how much it will cost to reach a higher level of efficiency based on the various factors that affect cost. We’ll also share a comparison table of other leading websites and what they estimate the costs will be, before sharing actual costs of homeowners like yourself.
Besides the size of your attic and how much insulation you add, the main factor that will affect cost is who does the work:
Before the cost per bag of insulation will mean anything, you must determine how much insulation is needed. Some home improvement sites have an insulation calculator like this one at Lowes but you can figure it out quickly using the information and equation below.
Cellulose insulation is sold most often in bags weighing about 20 pounds that will cover 40 square feet with R19 insulation. So, here’s how much you’ll need to achieve the desired R-value for your zone:
1). Divide the number of square feet in your attic by 40.
2). Multiply the result by the number of bags needed per 40 square feet to achieve the desired R-value.
For example, if you wanted an R38 upgrade in a 1,200 square foot attic:
The list below tells you the R-value of the attic insulation you currently have, so you’ll know how much to add.
Now, here are your costs:
Free rental: Some retailers offer free blower rental with the purchase of a minimum number of bags. For example, The Home Depot currently gives one day of rental with the purchase of 20+ bags.
Permits and Inspection Cost
Installation Cost and Time
As we noted, the cost of hiring a professional for attic insulation is roughly half the cost of the insulation. In the scenario we gave earlier, the cost of insulation would be about $400, and the labor would approximately $130, plus any travel time the company may charge for a small job like this.
Of course, pros consider the depth of the insulation required to achieve the desired R-value when estimating jobs. In other words, the more insulation/higher R-value they are adding, the higher the estimate. With that in mind, expect estimates to be in this range:
Blown In Attic Insulation Time Schedule
I’ve had the unfortunate pleasure of adding insulation to our current home. We have 1820 square feet of attic space and it only had 8 inches of insulation when we moved into our zone 4 home that was built in 1977. I added an average of 10 inches to reach the desired R60 rating, which was easy enough with a rented blower, but very tiresome and messy. We changed our gas furnaces (2) out at the same time, so calculating ROI was not an option, due to higher efficiency units.
The Family Handyman has a great DIY resource if you plan to do this yourself.
Several of thee sites below give a false positive of the costs you’ll pay for blown insulation. Costs calculated by the square foot will give you a much better idea of your own cost, versus flat rate pricing with no attic size qualification.
|Costimates||$.45 cents / sqft||$.30 – .80 cents / sqft|
|FixR||$400||$400 – $1,700|
|ImproveNet||$1,900||$1,700 – $2,100|
|HomeAdvisor||$1,360||$450 – $3,050|
|HomeWyse||$1,290||$800 – $1,550|
|Suggest a Cost Comparison from Another Website|