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Boost your home’s capacity to retain heat or cold by installing blown-in insulation. Blown-in insulation (also know as loose fill) is most commonly made of cellulose or fiberglass, although there is also mineral (rock or slag) wool. The installer uses an industrial blower to spray the loose fill material into the space; it sometimes can also be poured in. Blown-in insulation is a great option for enclosed existing walls or new open wall cavities, unfinished attic floors, irregularly shaped areas, and other hard-to-reach places, according to Energy.gov.

Installing loose fill insulation in your attic or walls will improve your home’s ability to prevent heat transfer, thereby keeping your home or office cooler in summer and warmer in winter. Blown-in insulation is a job best left to the pros, as a DIY rental machine may not be as effective as their specialized equipment. According to the Energy Program of Washington State University, cellulose can be a more effective insulator than fiberglass; loose fill cellulose has an R-value of 3.2-3.8 per inch, while loose fill fiberglass has an R-value of 2.2-2.7 per inch. The final R-value depends on the depth of the insulation and how densely it is installed.

Blown-in insulation is an environmentally friendly option. Loose fill cellulose insulation is made of up to 85 percent recycled paper, while fiberglass blown-in insulation is made of 20-30 percent recycled glass. Although it is made of recycled boxes, phone books and newspaper, cellulose is treated with fire retardants such as boric acid, so the insulation is not flammable.

In addition to maintaining your indoor temperatures, insulation saves you money otherwise lost through inefficient energy use. Heating and cooling bills can skyrocket when air seepage allows the indoor air inside and vice versa. If you’re ready to save money, keep cozy, and be environmentally friendly in the process, here are the cost factors for blown-in insulation.

Price per square foot

Many insulation specialists charge by the square foot for installing loose fill insulation. The base rate accounts for the cost of the insulation and materials, business overhead (insurance, company vehicles, blower machines, etc.), employee labor, and other expenses. Rates can vary by geographic region based on area costs of labor and other factors, so insulation installation may cost more in large cities than in rural communities. The type of insulation, the density and the brand will also impact price; for example, cellulose often costs more than fiberglass. Here are some examples of cost per square foot.

  • $1 per square foot for loose fill fiberglass from Russ Lewis of Green Attics in Fort Worth, Texas.

    • A 2,700-square-foot space added 8 inches of insulation for $1,800 to bring it up to an R-value of 30.

Location

Accessibility will impact cost of the installation. Unless you are installing insulation in new construction before drywall has been placed over the bare beams, it will cost more to install loose fill insulation into walls than attics, as the pros have to cut holes to allow entry into the wall. Here is an example of price difference between walls and attic in a finished structure from Juan Gutierrez of Capital Insulation in Tacoma, Washington:

  • $1.20-$1.25 per square foot for loose fill cellulose blown into an attic.

  • $1.50 per square foot for loose fill cellulose installed in finished walls.

Sealing and wiring

Several factors can increase your cost beyond the standard price per square foot, explains Gutierrez of Capital Insulation. These include whether the professional can install the insulation from the inside or the outside, the type of materials used to build the house, and the condition of the wiring in the attic and walls. Capital Insulation always air-seals the attic with spray foam and seals off electrical wiring gaps to ensure maximum efficiency once the insulation is installed.

Additional repairs

Another factor that can increase the cost of installing blown-in insulation is whether any existing insulation is rotted or has been damaged by water, rodents or mold. The pro may charge additional fees above the base price per square foot to account for removal. Removing old insulation requires the use of an industrial machine that can be damaged by wood chips or other obstructions — so any debris-ridden insulation must be bagged and removed by hand, increasing the total cost. If the old insulation is rotten or damaged and the customer opts not to have it removed, Gutierrez of Capital Insulation explains that his company will not take the job to protect the integrity of the work they might do. Here are some examples of cost for insulation removal.

  • Removal by machine: ~ $1 per square foot from Green Attics.

    • Complete removal of insulation in a 3,100-square-foot attic @ $1.10 per square foot = $3,410. Job took 12 hours.
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