The right basement insulation is key to a comfortable, cozy home all year long
Insulation can help regulate your basement's temperature, potentially saving you money on your monthly energy bills without sacrificing year-round comfort. Insulation also helps soundproof your basement, blocking outside noises for you and preventing your neighbors from hearing what's happening inside your household.
The best insulation for your basement depends on several factors, such as whether you're insulating your basement ceiling or walls. This guide outlines different types of basement insulation to help you choose the right type for your needs.
Understanding insulation R-values can help you choose the best insulation for your basement. R-values indicate how well different insulation types prevent heat from leaving your home, making it a good overall measure of effectiveness. The higher the R-value, the better the insulation keeps heat inside.
Typical R-value: 3.5–8.0
Foam board insulation comes in rigid sheets made of polystyrene or polyisocyanurate, and you can use it in both basement ceilings and walls. It's relatively inexpensive and easy to install —especially when installed before framing the walls—so it's a great option for DIYers on a budget. Foam board insulation is also low-maintenance and moisture-resistant, which is why it’s basement-approved.
Perfect for walls and ceilings
Moisture-resistant
Low-maintenance
Easy to install
Inexpensive
Air bubbles in polystyrene can accumulate some moisture
Must be very precisely cut to work effectively
Made of polyurethane, you can spray foam into small crevices, at which point it expands to fill the area completely. Spray foam insulation is ideal for filling remaining ceiling or wall cavities, such as gaps between wall studs. It doesn't retain moisture, so it won't cause mildew or mold, and it has strong sound absorption properties. However, spray foam insulation costs more than other insulation types.
Easily fills small gaps and crevices
Doesn't retain water
Strong sound absorption capabilities
More expensive than other insulation types
Not ideal for insulating large spaces
Typical R-value: 3.1–3.4
Fiberglass insulation is made of tiny glass fibers. It helps to regulate interior temperatures and offers strong soundproofing capabilities. However, it's not generally recommended for basement walls because it holds onto moisture, leading to water damage, mold, and mildew. But it can work well for insulating the basement ceiling when the basement isn't prone to moisture.
That said, fiberglass insulation is hazardous to your health if touched or inhaled, so you should always wear proper safety gear if you're handling it.
Excellent soundproofing capabilities
Doesn't retain water
Relatively inexpensive
Hazardous if touched or inhaled
Retains moisture
Not recommended for basement walls
Typical R-values: 3.1–3.4
Mineral wool insulation is a common alternative to fiberglass. It boasts a higher R-value than fiberglass, and it's often made from 30% recyclable materials. It's also moisture-resistant and can slow the spread of fires in the home, so it's ideal for basement walls and ceilings. However, it's typically more expensive than fiberglass.
Good for walls and ceilings
Made with recyclable materials
Higher R-value than fiberglass
Moisture- and fire-resistant
More expensive than fiberglass
Tougher to install than some other insulation types
Typical R-values: 3.2–3.8
Cellulose is a thick and dense loose-fill insulation derived from plant sources. It's usually composed of recycled paper and cardboard, making it more eco-friendly than other types. Cellulose is affordable and has a relatively high R-value, but it's not as moisture-resistant as some other insulation types, so it might be a better fit for basement ceilings than walls. It can also pack down over time, creating thermal bridges that move hot and cold air around, reducing its efficacy.
Affordable
Made of the most recycled materials out of all insulation options
Boasts a Class 1 Fire Retardant Rating
Higher R-value than fiberglass
Possible to install yourself
Less moisture-resistant than other insulation types
Might pack down over time, creating air leaks that minimize its efficacy
Not considered the best option for walls
Rigid foam board insulation is one of the safest insulation materials for basement walls. The panels offer a moisture barrier to prevent mold and mildew build-up. At the same time, this material is also fire-resistant, so you don’t have to worry as much about a fire breaking out as you would with spray foam insulation.
Yes, basement insulation needs a vapor barrier due to its susceptibility to moisture seeping in from the outside of the house. You should install a moisture barrier before you install insulation or purchase insulation that comes prebuilt with a moisture barrier to avoid water damage in your insulation and costly mold and water remediation expenses.
A plastic vapor barrier should completely cover your basement to prevent water from penetrating through the walls. This typically goes before installing insulation to prevent moisture from building up and becoming trapped on the inside of your insulation, where it can collect and lead to mold damage. Installing insulation after the vapor barrier allows for any moisture to exit the walls for better ventilation.
