Insulating Your Attic Can Save You Money
There’s no getting around it: If your house is in a cold climate, keeping it warm in winter is expensive. The Department of Energy predicts that prices for natural gas and heating oil will rise again this winter compared with last—and that’s after a year in which heating-oil prices rose sharply in most parts of the country.
Sure, you can dial down the thermostat and get used to wearing bulky sweaters indoors to cut costs. But if you’ve got an unfinished attic, giving it proper insulation is one of the simplest ways to keep a lid on your heating bill this season. The Department of Energy estimates that a properly insulated attic can shave 10 to 50 percent off your heating bill. And it works the opposite way for warm climates; in summer, it helps stabilize your house’s indoor temps to keep cooling needs in check.
In a perfect world, you’d hire an energy auditor to tell you exactly how much protection you’re getting from the few inches of attic insulation you may already have and to pinpoint things like air leaks that you can seal to make sure your insulation will do its job well. But if you can’t afford to shell out a few hundred bucks for this service, never fear: We’ve rounded up all the most important know-how about attic insulation costs, products, prep work, and installation right here. Keep reading for the details.
Attic Insulation Costs
According to Home Advisors, insulating your attic can cost between $1.50 to $3.50 Per Sqf. The main factors that impact the cost are:
- Type and material of your insulation
- Square footage of your attic
- Contractor or insulation installer’s fee
Note: If you have to insulate around electrical boxes or cables, then support from an electrician might be needed as part of the process too.
Start with The Attic Floor
Stop using your attic for storage. Why? Because the simplest and cheapest way to insulate an attic is to add material to the floor. But if the floor is covered in plywood, you can’t stuff enough insulation beneath it to do the job sufficiently—not even in warm climates.
Plan to pull up the flooring and layer new insulation on top of the old. With the floor gone, you’ll have to find a spot elsewhere for stashing those off-season clothes and that holiday decor.
Choose Your Insulation Type and Material
You’ve got two choices: loose fill or batt (the common term for blanket insulation). Both can be added to uninsulated attics or layered over existing material. Once you’ve decided which type is best for you, examine the material options and prices to home in on the right product. Always check labels for specifics on whatever you buy.
1. Loose fill
Insulation fibers are packaged in bags and blown in place to the desired depth and density using special machinery you can rent from a home center. You can pour the fill in place and spread it manually, but the process is much more labor-intensive and the results won’t be nearly as good.
It works best for:
- Attics with irregular or nonstandard joist spacing
- Attics with lots of obstructions and penetrations to work around
- Attics where there is existing insulation to be topped, since it fills gaps and joints well
- Low-clearance attics with limited headroom for maneuvering during installation
- DIYers who want to get the job done quickly and are comfortable working with power equipment
Insulation material options:
Fiberglass
- R-value per inch: 2.2–2.7
- Made of: Recycled glass or sand that’s melted and spun into fibers
- Bottom line: Lighter in weight than cellulose or mineral wool, but it settles more than those materials, so you’ve got to put in a thicker layer to get the protection you need.
Cellulose
- R-value per inch: 3.2–3.8
- Made of: Fibers from recycled post-consumer paper that are treated for insect and fire resistance
- Bottom line: The most common blown-in material used, but it can rot and grow moldy if exposed to moisture.
Mineral wool
- R-value per inch: 3.0–3.3
- Made of: Fibers from rock or recycled slag from blast furnaces
- Bottom line: Offers natural fire resistance, but costs more than other loose-fill materials.
2. Batts
This flexible insulation material is most often packaged in rolls that come in various thicknesses and standard widths, usually 16 inches and 24 inches, to fit between joists or studs in a house’s framing. They come with or without a paper or foil facing that acts as a vapor barrier. You add one or more layers to achieve the desired level of insulation.
They work best for:
- Attics with standard joist spacing, especially those with no insulation
- Attics with few obstructions or penetrations to work around
- Attics with sufficient headroom for maneuvering during installation
- DIYers who don’t mind cutting the material to fit around obstructions
Insulation material options:
Fiberglass
- R-value per inch: 2.9–4.3
- Made of: Recycled glass or sand that’s melted and spun into fibers
- Bottom line: Commonly used and inexpensive, but fibers can irritate lungs and skin (though less so than in years past, thanks to better manufacturing), and it’s less effective at blocking airflow than other materials.
Cellulose
- R-value per inch: 3.7–3.8
- Made of: Fibers from recycled post-consumer paper that are treated for insect and fire resistance.
- Bottom line: Won’t irritate lungs or skin, but the product is made by a limited number of manufacturers.
Mineral wool
- R-value per inch: 3.0–3.3
- Made of: Fibers from rock or recycled slag from blast furnaces
- Bottom line: It’s naturally fire-resistant, but the product is more expensive than others.
Cotton
- R-value per inch: 3.7–3.8
- Made of: Fibers from recycled denim cloth
- Bottom line: Blocks airflow and sound transmission, but the material is more expensive than others.
Size Up Your Existing Insulation (and Get Rid of The Bad Stuff)
Owners of houses built before 1990 take note: If what you see is lightweight, grainy, loose-looking insulation with shiny flecks, it could be vermiculite from a mine with asbestos deposits. Get it tested, and if necessary, call in a pro to remove and haul it away safely.
The Number One Prep Step: Seal Air Leaks
Gaps in the attic or between the lower floors and the attic will let heated (or cooled) air escape to the great, unconditioned outdoors, making any insulation you add essentially useless. Here’s a quick primer on fixing draft-prone spots.
- Around attic windows: Use canned, minimally-expanding spray foam around the casing, and foam weather-stripping to seal leaks around the sash and jambs.
- Around pipes, wires, exhaust fans, and ducts: Gaps of ¼ inch or less can be sealed with fire-blocking caulk seal larger ones up to ½ inch with fire-blocking spray foam.
- Around chimneys and flues: Use metal flashing sealed with high-temperature caulk or furnace cement.
Other Key Prep Steps Before You Insulate
Knock these to-dos off your list to ensure that your insulation will last for years and keep conditioned air where it belongs: inside your house.
- Fix roof leaks. Water is insulation’s enemy. It creates a breeding ground for mold and mildew and ruins the air-trapping pockets that block heat flow. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.
- Box out light fixtures. Unless you’re using mineral-wool insulation or your fixtures are rated safe for contact with any type of insulation, don’t allow the material to touch or cover recessed cans or lights from the floor below—it’s a fire hazard. Use hardware cloth, metal flashing, or scrap plywood to create a safety gap of at least 3 inches all around fixtures.
- Direct all exhaust fans and vents to the exterior. Though it’s against building code to vent any kind of exhaust to an attic space, many home builders have gotten away with this shortcut. Correct that mistake so that humid exhaust air doesn’t get trapped in your insulation and ruin it.
Preserve The Attic’s Airflow
Covering up the soffit vents with loose fill or batts, which can happen if you stuff insulation along the eaves, is a huge no-no. The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams, and the material will block that flow. For the same reason, insulation shouldn’t touch the roof’s underside. Staple plastic or foam baffles to the roof sheathing, near the eaves, to keep the material away.
If You’re Insulating from Scratch, Put The Right Vapor Barrier in The Right Place
Though some batts come with a paper or foil facing that can act as a vapor barrier, Tom Silva prefers to use 6-mil polyethylene sheeting, cut to fit between the joists and with seams sealed by foil tape, to prevent moisture from seeping into insulation. Whether using loose fill or batts, put the vapor barrier closest to the warm side of your installation, where hot, moist air would get in—facing the house’s interior in cold climates (beneath floor insulation) and the attic’s interior in hot climates (on top of floor insulation). Some regions don’t require a vapor barrier.Insulating Your Attic Can Save You Money
There’s no getting around it: If your house is in a cold climate, keeping it warm in winter is expensive. The Department of Energy predicts that prices for natural gas and heating oil will rise again this winter compared with last—and that’s after a year in which heating-oil prices rose sharply in most parts of the country.
Sure, you can dial down the thermostat and get used to wearing bulky sweaters indoors to cut costs. But if you’ve got an unfinished attic, giving it proper insulation is one of the simplest ways to keep a lid on your heating bill this season. The Department of Energy estimates that a properly insulated attic can shave 10 to 50 percent off your heating bill. And it works the opposite way for warm climates; in summer, it helps stabilize your house’s indoor temps to keep cooling needs in check.
In a perfect world, you’d hire an energy auditor to tell you exactly how much protection you’re getting from the few inches of attic insulation you may already have and to pinpoint things like air leaks that you can seal to make sure your insulation will do its job well. But if you can’t afford to shell out a few hundred bucks for this service, never fear: We’ve rounded up all the most important know-how about attic insulation costs, products, prep work, and installation right here. Keep reading for the details.
Attic Insulation Costs
According to Home Advisors, insulating your attic can cost between $1.50 to $3.50 Per Sqf. The main factors that impact the cost are:
- Type and material of your insulation
- Square footage of your attic
- Contractor or insulation installer’s fee
Note: If you have to insulate around electrical boxes or cables, then support from an electrician might be needed as part of the process too.
Start with The Attic Floor
Stop using your attic for storage. Why? Because the simplest and cheapest way to insulate an attic is to add material to the floor. But if the floor is covered in plywood, you can’t stuff enough insulation beneath it to do the job sufficiently—not even in warm climates.
Plan to pull up the flooring and layer new insulation on top of the old. With the floor gone, you’ll have to find a spot elsewhere for stashing those off-season clothes and that holiday decor.
Choose Your Insulation Type and Material
You’ve got two choices: loose fill or batt (the common term for blanket insulation). Both can be added to uninsulated attics or layered over existing material. Once you’ve decided which type is best for you, examine the material options and prices to home in on the right product. Always check labels for specifics on whatever you buy.
1. Loose fill
Insulation fibers are packaged in bags and blown in place to the desired depth and density using special machinery you can rent from a home center. You can pour the fill in place and spread it manually, but the process is much more labor-intensive and the results won’t be nearly as good.
It works best for:
- Attics with irregular or nonstandard joist spacing
- Attics with lots of obstructions and penetrations to work around
- Attics where there is existing insulation to be topped, since it fills gaps and joints well
- Low-clearance attics with limited headroom for maneuvering during installation
- DIYers who want to get the job done quickly and are comfortable working with power equipment
Insulation material options:
Fiberglass
- R-value per inch: 2.2–2.7
- Made of: Recycled glass or sand that’s melted and spun into fibers
- Bottom line: Lighter in weight than cellulose or mineral wool, but it settles more than those materials, so you’ve got to put in a thicker layer to get the protection you need.
Cellulose
- R-value per inch: 3.2–3.8
- Made of: Fibers from recycled post-consumer paper that are treated for insect and fire resistance
- Bottom line: The most common blown-in material used, but it can rot and grow moldy if exposed to moisture.
Mineral wool
- R-value per inch: 3.0–3.3
- Made of: Fibers from rock or recycled slag from blast furnaces
- Bottom line: Offers natural fire resistance, but costs more than other loose-fill materials.
2. Batts
This flexible insulation material is most often packaged in rolls that come in various thicknesses and standard widths, usually 16 inches and 24 inches, to fit between joists or studs in a house’s framing. They come with or without a paper or foil facing that acts as a vapor barrier. You add one or more layers to achieve the desired level of insulation.
They work best for:
- Attics with standard joist spacing, especially those with no insulation
- Attics with few obstructions or penetrations to work around
- Attics with sufficient headroom for maneuvering during installation
- DIYers who don’t mind cutting the material to fit around obstructions
Insulation material options:
Fiberglass
- R-value per inch: 2.9–4.3
- Made of: Recycled glass or sand that’s melted and spun into fibers
- Bottom line: Commonly used and inexpensive, but fibers can irritate lungs and skin (though less so than in years past, thanks to better manufacturing), and it’s less effective at blocking airflow than other materials.
Cellulose
- R-value per inch: 3.7–3.8
- Made of: Fibers from recycled post-consumer paper that are treated for insect and fire resistance.
- Bottom line: Won’t irritate lungs or skin, but the product is made by a limited number of manufacturers.
Mineral wool
- R-value per inch: 3.0–3.3
- Made of: Fibers from rock or recycled slag from blast furnaces
- Bottom line: It’s naturally fire-resistant, but the product is more expensive than others.
Cotton
- R-value per inch: 3.7–3.8
- Made of: Fibers from recycled denim cloth
- Bottom line: Blocks airflow and sound transmission, but the material is more expensive than others.
Size Up Your Existing Insulation (and Get Rid of The Bad Stuff)
Owners of houses built before 1990 take note: If what you see is lightweight, grainy, loose-looking insulation with shiny flecks, it could be vermiculite from a mine with asbestos deposits. Get it tested, and if necessary, call in a pro to remove and haul it away safely.
The Number One Prep Step: Seal Air Leaks
Gaps in the attic or between the lower floors and the attic will let heated (or cooled) air escape to the great, unconditioned outdoors, making any insulation you add essentially useless. Here’s a quick primer on fixing draft-prone spots.
- Around attic windows: Use canned, minimally-expanding spray foam around the casing, and foam weather-stripping to seal leaks around the sash and jambs.
- Around pipes, wires, exhaust fans, and ducts: Gaps of ¼ inch or less can be sealed with fire-blocking caulk seal larger ones up to ½ inch with fire-blocking spray foam.
- Around chimneys and flues: Use metal flashing sealed with high-temperature caulk or furnace cement.
Other Key Prep Steps Before You Insulate
Knock these to-dos off your list to ensure that your insulation will last for years and keep conditioned air where it belongs: inside your house.
- Fix roof leaks. Water is insulation’s enemy. It creates a breeding ground for mold and mildew and ruins the air-trapping pockets that block heat flow. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.
- Box out light fixtures. Unless you’re using mineral-wool insulation or your fixtures are rated safe for contact with any type of insulation, don’t allow the material to touch or cover recessed cans or lights from the floor below—it’s a fire hazard. Use hardware cloth, metal flashing, or scrap plywood to create a safety gap of at least 3 inches all around fixtures.
- Direct all exhaust fans and vents to the exterior. Though it’s against building code to vent any kind of exhaust to an attic space, many home builders have gotten away with this shortcut. Correct that mistake so that humid exhaust air doesn’t get trapped in your insulation and ruin it.
Preserve The Attic’s Airflow
Covering up the soffit vents with loose fill or batts, which can happen if you stuff insulation along the eaves, is a huge no-no. The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams, and the material will block that flow. For the same reason, insulation shouldn’t touch the roof’s underside. Staple plastic or foam baffles to the roof sheathing, near the eaves, to keep the material away.
If You’re Insulating from Scratch, Put The Right Vapor Barrier in The Right Place
Though some batts come with a paper or foil facing that can act as a vapor barrier, Tom Silva prefers to use 6-mil polyethylene sheeting, cut to fit between the joists and with seams sealed by foil tape, to prevent moisture from seeping into insulation. Whether using loose fill or batts, put the vapor barrier closest to the warm side of your installation, where hot, moist air would get in—facing the house’s interior in cold climates (beneath floor insulation) and the attic’s interior in hot climates (on top of floor insulation). Some regions don’t require a vapor barrier.