What Is the Best Insulation for Your Basement?

The right basement insulation is key to a comfortable, cozy home all year long

A nice renovated basement
Photo: PC Photography / iStock / Getty Images Plus / Getty Images
A nice renovated basement
Photo: PC Photography / iStock / Getty Images Plus / Getty Images
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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.

But First, What Are R-Values?

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. 

5 Best Types of Insulation for Your Basement Walls and Ceiling

Foam Board Insulation

Foam board insulation
Photo: bilanol / Adobe Stock

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. 

Pros

  • Perfect for walls and ceilings

  • Moisture-resistant

  • Low-maintenance

  • Easy to install

  • Inexpensive

Cons

  • Air bubbles in polystyrene can accumulate some moisture

  • Must be very precisely cut to work effectively

Spray Foam Insulation

Spray foam insulation
Photo: C5Media / Adobe Stock

Typical R-value: 3.6–3.9

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. 

Pros

  • Easily fills small gaps and crevices

  • Doesn't retain water

  • Strong sound absorption capabilities

Cons

  • More expensive than other insulation types

  • Not ideal for insulating large spaces

Fiberglass Insulation

A worker installing fiberglass Insulation
Photo: DonNichols / E+ / Adobe Stock

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. 

Pros

  • Excellent soundproofing capabilities

  • Doesn't retain water

  • Relatively inexpensive

Cons

  • Hazardous if touched or inhaled

  • Retains moisture

  • Not recommended for basement walls

Mineral Wool Insulation

A worker installing mineral wool insulation
Photo: Bilanol / iStock / Getty Images Plus / Getty Images

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.

Pros

  • Good for walls and ceilings

  • Made with recyclable materials

  • Higher R-value than fiberglass

  • Moisture- and fire-resistant

Cons

  • More expensive than fiberglass

  • Tougher to install than some other insulation types

Cellulose Insulation

Cellulose building insulation
Photo: Ingo Bartussek / Adobe Stock

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. 

Pros

  • 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

Cons

  • 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

Frequently Asked Questions

When choosing a professional insulation installer, consider asking these questions to determine the best fit.

  • Will you address air leaks in my house?

  • Can you provide an R-value (heat resistance) fact sheet?

  • What kind of insulation will work best for my home?

  • How do you handle signs of a water leak?

  • Are you licensed and insured?

  • Can you provide customer references?

The best type of insulation for your home depends on what you need, so the answer will depend on your specific situation. If you’re building a house, structural panels are easy to install during the building process in addition to being the most energy efficient type. If you live in a warm climate, reflective insulation may benefit you more as it costs less than other insulation types. And for standard attics, loose-fill, spray foam, or blown-in insulation work well.

If you plan to heat or cool your garage, you’ll need to insulate the garage ceiling. Insulating your garage ceiling will make your garage much more energy efficient and save on heating and cooling costs. Not only does insulation make your garage more energy efficient, it helps reduce noise and can extend the life of your garage roof. You can use fiberglass, cellulose, mineral wool, or spray foam insulation for this project.

In some cases, you may not have enough insulation to properly regulate your home’s temperature. Watch for a few signs your home needs more insulation, such as:

  • High heating and cooling bills

  • Uncomfortable room temperatures 

  • Ice dams on the edge of your roof 

  • Roof leaks

  • Cold floors and walls

  • Freezing pipes

  • Temperature fluctuations

  • Visibly low insulation

  • Noise problems

  • Pest problems

On average, insulating an attic costs about $2,500, ranging from $1,500 to $3,500, depending on the insulation type, amount, and your attic’s accessibility. Additional cost factors include sealing air leaks, removal or replacement of insulation, and inspections. Types of insulation include:

  • Blown-in: $1–$4 per square foot

  • Spray foam: $2–$5 per square foot

  • Batt: $2–$4 per square foot

  • Structural insulated panels: $4–$7 per square foot

  • Loose-fill: $2–$5 per square foot

  • Reflective: $0.50–$1.50 per square foot

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