Adding insulation to your home is one of the best investments you can make and can potentially save you big on energy bills over time; you may even get a tax credit in some states. Even if it seems expensive upfront, you're likely to recoup that money through lower utility bills over time. Installing blown-in insulation may boost your home's capacity to retain heat or cold as well help neutralize humidity. On average, the cost of adding blown-in insulation to an existing home ranges from $800 to $2,000.
Blown-in insulation (also know as loose fill) is most commonly made of cellulose or fiberglass, although there is also insulation made of 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 can be 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 generally improve your home's ability to prevent heat transfer, thereby typically keeping your home or office cooler in summer and warmer in winter. Blow-in insulation is a job best left to the professionals, as a DIY rental machine may not be as effective as their specialized equipment. An insulation contractor can also help make sure you choose the best insulation type or material for your size home and your local climate.
In addition to maintaining your indoor temperatures, insulation can save you money otherwise lost through inefficient energy use. Heating and cooling bills can skyrocket when air seepage allows the indoor air outside and vice versa. If you're ready to save money, keep cozy and be environmentally friendly in the process, here are the average cost factors for blow-in insulation.
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:
- Low cost
- Increased design flexibility
- Inert nature that doesn't settle
- Natural noncombustibility
- Ability to decrease sound pollution
- Resistance to moisture
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
- High energy efficiency
- Resistance to airflow
- 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
- Moisture resistance
- Sustainable and recyclable nature
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.
Price per square foot
Many insulation specialists charge by the square foot for installing loose fill insulation. 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.
Where to add insulation
For optimal energy efficiency, your home should be insulated from the roof down to the foundation — yet many homeowners believe only attics should be insulated. Blown-in insulation can be installed in an unfinished attic space, the crawl space below the house, and exterior walls. It can provide significant air sealing, which can make a drafty home feel much cozier and warmer. Also, blown-in insulation can be added to exterior walls without having to open large holes in your finished walls.
Accessibility can impact cost of the installation. Unless you are installing insulation in new construction before drywall has been placed over the bare beams, it will usually 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
For most exterior walls, experts recommend an R-value of R-13 to R-24; because the space inside a wall is filled almost completely with insulation, the R-values can be lower than in attics, which have negative space not filled with insulation.
For example, filling 1,000 square feet of wall space with 13 bags of R-13 fiberglass loose fill insulation will cost about $430, on average, including labor. The highest R-level recommendation for walls is R-24, and it costs about $1,000 to cover 1,000 square feet of wall space on average.
Sealing and wiring
Several factors can increase your cost beyond the standard price per square foot, explains Gutierrez of Capital Insulation. 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.
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 @ $1.10 per square foot = $3,410. Job took 12 hours.
Because there are many companies offering blown-in insulation services in most areas, prices remain competitive. The greatest cost savings come from lowered utility bills after the insulation has been installed. According to Energy Star, the national average savings through insulation is 15 percent on heating and cooling bills — that can be as much as $600 in just one year.
- Loose fill cellulose can be dusty when blown in, so always confirm your company will take adequate measures to keep your home or office clean.
- The discovery of mold or asbestos will likely increase your total cost, as the hazardous material must be safely removed before insulation can be installed.
- Read client reviews and follow up with references to make sure you're choosing the right pro for your project. For more, check out our tips for smart hiring.