Many insulation specialists charge by the square foot for installing loose fill insulation. Blown in insulation per square foot costs can range anywhere from $0.17-$2.66. However, this can vary depending on the contractor or company. For example, some may charge closer to $1-$1.50 per square foot.
The base rate typically accounts for the cost of the insulation and materials, business overhead (including 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 may also impact price; for example, cellulose often costs more than fiberglass.
On average, a 28.5-pound bag of fiberglass loose fill insulation costs $33. Installing 15 bags of R-30 loose fill insulation per 1,000 square feet would cost about $500 on average, which includes labor fees. Installing 32 bags of R-60 loose fill insulation, also covering 1,000 square feet, would cost about $1,000, on average.
For example, Russ Lewis of Green Attics in Fort Worth, Texas, charges $1 per square foot for loose fill fiberglass; a 2,700-square-foot space with an additional 8 inches of insulation for $1,800 brings the home up to an R-value of 30.
On average, a 19-pound bag of blown-in cellulose insulation also costs about $30, but it covers about one-fourth of the amount of space as fiberglass loose fill insulation. Cellulose is a more natural alternative to fiberglass, but it's generally more expensive.
How do I estimate the cost of insulation?
To estimate the cost of blown-in insulation, you'll need to take a few factors into account. For example:
R-value
R-value is a measure of insulation's ability to resist heat traveling through it. It's also used to specify a home's insulation level, key to the building's overall energy efficiency. Generally, the higher the R-value, the better the thermal performance of the insulation or the better a home's insulation rating.
Different levels of insulation are cost-effective for different climates as well as different locations in the home. Because insulation with higher R-values is thicker than insulation with lower R-values, it's also typically more expensive. A value of R-30 is often the minimum recommended value for attic insulation materials in all homes across the United States.
For example, the U.S. Department of Energy recommends that homes in Hawaii have R-values that range from R-30 to R49, while homes in much of California and Texas should range from R-30 to R-60. The Department of Energy recommends an R-value of R-38 to R-60 for homes in the coldest states, such as New York and Minnesota.
Fiberglass vs. cellulose vs. rock wool fiber
According to the Energy Program of Washington State University, cellulose can be a more effective insulator than fiberglass insulation; 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 generally 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 typically treated with fire retardants such as boric acid, so the insulation is not flammable.
Fiberglass is the most common residential insulation, in no small part because it's usually the least expensive option for blown-in insulation. It can be used either by itself or as a topper to cellulose insulation because it adds fire retardancy. Advantages of fiberglass loose-fill insulation include its:
Increased design flexibility
Inert nature that doesn't settle
Natural noncombustibility
Ability to decrease sound pollution
In contrast, cellulose has a higher per-inch R-value than fiberglass and, because it's made of plant fibers, can be less dangerous to install. Unlike fiberglass, cellulose can be damaged by moisture, so it may require an additional vapor-retardant material on any side of the wall or ceiling adjacent to a conditioned space. Advantages of cellulose include its:
Lower environmental impact
Lack of corrosion to steel, copper and aluminum
Rock wool fiber is the least common type of blown-in insulation, probably because of its typical high cost. Made from post-consumer recycled materials and metals, it is generally both environmentally friendly and resistant to fire. The inorganic materials in rock wool fiber also make it highly sound-resistant. This type of insulation is often used for additional fire protection and soundproofing. Advantages to rock wool fiber include its:
Ability to naturally repel pests
Sustainable and recyclable nature
Local labor costs
The local cost of materials and labor will also likely affect your overall cost estimate for blown-in insulation, regardless of what type of material you use.
Sealing and wiring
Several factors can increase your cost beyond the standard price per square foot, explains Juan Gutierrez of Capital Insulation in Tacoma, Washington. These may 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 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 typically requires the use of an industrial machine that can be damaged by wood chips or other obstructions — so any debris-ridden insulation should 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: about $1 per square foot from Green Attics.
Complete removal of insulation in a 3,100-square-foot attic at $1.10 per square foot = $3,410.
Note: This job took 12 hours to complete.
Is blown-in insulation expensive?
Blown-in insulation can be more expensive and cheaper than other types of insulation. Here's a look at a few cost estimates for blown-in, spray foam, batt and roll insulation costs:
Type of insulation | Estimate cost per square foot |
---|
Blown-in insulation | $0.17-$2.66 |
Batt or roll insulation | $0.50-$2.18 |
Rigid foam insulation | $0.90-$1.88 |
Spray foam insulation | $3.00-$5.00 |
Remember: the cost install blown-in insulation in your home will vary depending on the professional you hire for the job. That's why it's always important to get multiple cost estimates before choosing a pro.