Energy cost · Insulation
Blown-In Insulation Cost
Blown-in attic insulation
Bottom line: Blown-in insulation costs $1.00 to $2.80 per square foot installed for fiberglass or cellulose, and $1.90 to $4.20 for rock wool, according to HomeGuide. Insulating an attic floor costs $900 to $3,600, while blowing insulation into exterior walls costs $1,900 to $7,800. Bringing 1,000 sq ft of attic to R-38 costs $840 to $1,500.
HomeGuide puts it at $1.00 to $2.80 per square foot installed for fiberglass or cellulose.
Cost by material (installed, per sq ft)
| Material | Cost (HomeGuide) |
|---|---|
| Fiberglass | $1.00 – $2.80 |
| Cellulose | $1.20 – $2.80 |
| Rock wool | $1.90 – $4.20 |
Attic vs walls
| Area | Per sq ft | Total (HomeGuide) |
|---|---|---|
| Attic floor | $0.90 – $2.40 | $900 – $3,600 |
| Exterior walls | $1.10 – $3.70 | $1,900 – $7,800 |
Cost by R-value (per 1,000 sq ft)
| R-value | Depth | Cost (HomeGuide) |
|---|---|---|
| Attic R-30 | 10.25 in | $660 – $1,200 |
| Attic R-38 | 13 in | $840 – $1,500 |
| Attic R-49 | 16.5 in | $1,100 – $1,900 |
| Attic R-60 | 20 in | $1,400 – $2,400 |
| Wall R-13 | 3.5 in | $1,100 – $2,400 |
| Wall R-21 | 5.5 in | $1,700 – $3,300 |
Cost by home size
| Home | Cost (HomeGuide) |
|---|---|
| 1,000 sq ft | $1,000 – $2,800 |
| 2,000 sq ft | $2,000 – $5,600 |
| 3,000 sq ft | $3,000 – $8,400 |
DIY
HomeGuide lists blower machine rental at $100 to $200 per day and an average DIY project at $500 to $1,200.
For other insulation types, see attic insulation cost.
Cost by area of the house (HomeGuide)
| Area | Cost |
|---|---|
| Garage attic floor | $520 – $1,400 |
| Garage walls | $950 – $3,200 |
| 2-car garage, all | $1,400 – $4,600 |
| Whole house, new construction | $3,500 – $11,600 |
| Whole house, existing home | $4,500 – $16,000 |
HomeGuide's national average for a blown-in job is $1,900, with most between $800 and $3,000. Some companies require a $1,500 to $2,000 minimum.
Cellulose methods
Wet-spray cellulose runs $0.60 to $2.00 per sq ft and dense-pack cellulose, used in closed walls, $1.60 to $4.20 (HomeGuide).
Loose-fill brands (R-19, material only, per sq ft)
| Brand | Material | Price |
|---|---|---|
| Owens Corning | Fiberglass | $0.30 – $0.60 |
| Green Fiber | Cellulose | $0.30 – $0.60 |
| Johns Manville | Fiberglass | $0.40 – $0.80 |
| Nu-Wool | Cellulose | $1.30 – $2.00 |
| American Rockwool | Rockwool | $1.75 – $2.50 |
Labor and prep
Labor runs $0.70 to $1.70 per sq ft, or $40 to $80 per hour. Removing old insulation adds $1 to $2 per sq ft, air sealing $350 to $3,000 and a roof vent $200 to $700 (HomeGuide).
A 30-lb bag of blown-in insulation costs $30 to $40, and DIY jobs run $0.35 to $1.50 per sq ft (HomeGuide).
What blown-in insulation is
Blown-in insulation is loose material, usually fiberglass or cellulose, blown into attics or walls with a machine. It fills gaps and covers uneven spaces better than batts.
Fiberglass vs. cellulose
- Fiberglass: light, does not absorb water easily, and does not settle much.
- Cellulose: denser, made from recycled paper, and good at blocking air movement. It can settle over time.
Where it is used
- Attic floors: the most common use.
- Existing walls: installed through small holes drilled in the wall, then patched.
- Hard-to-reach spaces: where batts are hard to fit.
What affects the price
- Area and depth.
- Material type.
- Air sealing and baffles.
- Access to the attic.
- Wall installation, which involves drilling and patching.
Questions to ask
- What R-value and depth will you install?
- Will you mark the depth with rulers in the attic?
- How will you keep vents and recessed lights safe?
In Texas
Texas attics get very hot in summer, so insulation depth matters for comfort. Many electric providers in Texas offer energy efficiency programs; check before choosing a contractor.
How blown-in insulation is installed
The installer sets up a blowing machine outside or in the garage and runs a long hose into the attic. Loose-fill insulation is fed into the machine, which breaks it up and blows it through the hose. The installer spreads it evenly across the attic floor to the target depth, using depth rulers fastened to the joists to check coverage. Before blowing, baffles are installed at the eaves, recessed lights and chimneys are protected with dams or covers where required, and the attic hatch is weatherstripped and insulated.
For walls, installers drill small holes in the siding or the interior drywall, blow insulation into the wall cavities, and plug and patch the holes. This is called dense-pack insulation.
More on fiberglass vs. cellulose
Loose-fill fiberglass is made of glass fibers. It does not settle much, resists moisture and mold and is not combustible.
Cellulose is made largely from recycled paper treated with fire retardants. It is denser, which helps it reduce air movement and sound, and it fills gaps well. It can settle over time, so installers add extra depth.
Both work well when installed to the right depth.
Settling and depth
Loose-fill insulation can settle after installation, especially cellulose. Manufacturers specify the installed thickness needed to reach the labeled R-value after settling. Ask your installer what depth they will install and how many bags they will use for your attic.
Where blown-in works best
Blown-in insulation is ideal for attics with irregular joist spacing, obstructions and hard-to-reach corners. It is also the main option for adding insulation to existing walls without removing drywall.
Preparing for installation
Before insulation is blown in, the installer should check the attic for problems that insulation would hide, such as roof leaks, damaged wiring and gaps that need air sealing. Baffles are installed at the eaves so insulation does not block soffit vents, and dams are placed around the attic hatch. Recessed lights that are not rated for insulation contact need covers or replacement to prevent overheating. After installation, depth markers or rulers stapled to the rafters show how much insulation was installed, which helps you confirm you got the depth you paid for.
Blown-in insulation in existing walls
Insulating the walls of a finished house without removing drywall is done with the drill-and-fill method. The installer drills small holes between studs, either from the outside under siding or from the inside, and blows dense-pack cellulose or fiberglass into each cavity until it is full. The holes are then plugged and patched. Fire blocks, plumbing and wiring inside walls can leave voids, so an experienced installer checks each cavity, sometimes with an infrared camera, to confirm it was filled. Because the work happens one cavity at a time, wall jobs cost more per square foot than attic floors.
Fire safety around chimneys and lights
Insulation must keep its required clearance from chimneys, flues and recessed lights not rated for contact. Installers use metal flashing or barriers to hold it back.
Sources
General contractors in Texas
Our Texas business directory lists 3,666 general contractors across 6 major cities. The ratings below are the average Google rating of the listed businesses in each city, and the review counts are the total number of Google reviews they have received.
| City | Businesses listed | Avg. Google rating | Total reviews |
|---|---|---|---|
| Houston | 1,568 | 4.4 | 21,319 |
| Dallas | 494 | 4.3 | 6,725 |
| San Antonio | 509 | 4.2 | 9,067 |
| Austin | 556 | 4.3 | 9,044 |
| Fort Worth | 332 | 4.3 | 3,892 |
| El Paso | 207 | 4.1 | 2,486 |
Source: twupro Texas business directory, built from public Google Maps listings.
Talk to local installers
Compare local electricians and solar installers with reviews and phone numbers in your area.