Average Basement Insulation Cost – Forbes Advisor


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Insulating any part of your home is usually one of the best investments you can make as a homeowner. The basement is an area where a lot of cold air resides, but adding insulation to the basement can stop cold leaks, increase energy efficiency, and reduce energy bills. Additionally, sealing a basement can prevent moisture issues like mold and pests from entering the home. Insulating a basement is one of the first steps toward finishing a basement, which adds livable space to your home and increases its value.

Is it worth insulating a basement?

Determining whether it’s worth insulating a basement depends on your needs and your climate. Energy Star provides a climate zone map that homeowners can use to determine the proper insulation they need based on R-value. Building Science Corporation has a good guide for basement insulation for climate zones four through eight. Homes in climate zones one through three generally do not have a basement.

The Environmental Protection Agency estimates that homeowners can save up to 20% on utilities by insulating certain parts of the home. By insulating a basement, a homeowner can expect to recoup installation costs in less than two years through energy savings.

Types of Basement Insulation

Rigid foam

Rigid foam insulation is made of long sheets of insulation, often pink in color. Rigid foam generally costs more than fiberglass insulation. Rigid foam insulation is also known as XPS and extruded polystyrene insulation. Rigid foam insulation boards vary in thickness up to two inches. Each inch of thickness represents an R-value of R5.

Rigid foam insulation kits are available, but the cost of individual panels varies from approx. $15 to $35 per sheet, which can add up quickly if you have a large basement.

spray foam

Spray foam will come in open cell and closed cell variety. Contractors often suggest using open cell spray foam for areas above ground level and closed cell in below grade spaces. Closed-cell spray foam is an absolute vapor barrier, preventing moisture from passing through it, but it can also hide leaks that can lead to mold growth. Open cell spray foam does not retain water and leaks will be visible.

Closed cell spray foam is denser than open cell spray foam and has an R-value of 7 per inch. For closed cell spray foam to work as intended, there will need to be a complete vapor barrier between the concrete and the interior building material. Some contractors will suggest installing exterior wall studs at least one inch from the wall.

Spray foam insulation should be done by a professional because of the hazards of working with spray foam and the precision required. Once applied, it usually takes a day for the spray foam to harden.

fiberglass bat

Fiberglass batt insulation is also known as blanket insulation due to its fluffy appearance. Fiberglass batt comes in the form of flat pieces of fiberglass or mineral wool. Some fiberglass insulation comes with foil or paper, while others do not. The need for siding depends on the climatic zone of the house. Fiberglass batt is one of the cheapest insulation materials available.

Anyone working with a fiberglass mattress will need to protect themselves with a mask and protective clothing, as fiberglass is a skin and lung irritant. Fiberglass tablecloth is more suitable for DIY than other insulating materials.


Blown-in insulation, or loose-fill insulation, is sprayed into place with special insulation tools and is typically used in attics. Blown-in insulation is often made of fiberglass, cellulose, or mineral wool. Cellulose tends to retain water more than other insulating materials. Blown-in insulation is typically used in finished areas of a home and can fill gaps between existing wall studs.

Homeowners should address any moisture issues before applying blown-in insulation and note the location of electrical boxes. To fill in existing walls, homeowners need to find a place to drill in order to install a pipe to blow through the insulation. Homeowners will often need a vapor barrier in place if they choose blown-in insulation that touches the concrete.

Radiant wall barrier

For homeowners who don’t want to finish a basement, but still want to insulate it better, a radiant wall barrier is an option. Radiant wall barriers use a reflective material, such as aluminum foil. Some companies claim that a radiant wall barrier will help retain heat in the home and protect a basement from moisture by creating a vapor barrier and a path for water.

basement insulation cost per square foot

Foam Insulation Cost Per Square Foot

Benefits of Basement Insulation

  • Reduces heating costs by approximately 20%
  • Serves as a first step to finishing a basement, which will increase usable living space
  • Incredible nearly 100% return on investment
  • Reduces potential water problems

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Disadvantages of Basement Insulation

  • Initial costs: Insulating a basement can cost thousands of dollars depending on the size of the basement and the type of insulation used.
  • Discover the problems: Once you start looking at your basement, you might find a few surprises. Maybe the house was previously poorly insulated or you find major air leaks that need more repairs than expected.
  • Reduced space: Though minor, but depending on the level of insulation, homeowners might see a reduction in basement space.

Labor costs for basement insulation

The national average cost to insulate a basement ranges from $1,400 to $6,300, depending on the size of the basement and the type of insulation used. Labor costs can vary between $0.25 to $0.50 per square foot to insulate a basement.

Do-it-yourself or hire a pro?

Insulating a basement is and is not a DIY project. Installing rigid foam insulation or fiberglass batt insulation is more of a DIY project than blown insulation or spray foam insulation because blown insulation and foam insulation sprayed require special tools and expertise to do it perfectly.

Properly insulating a basement is important because a poorly insulated basement can lead to water problems and more costly problems down the road.

Frequently Asked Questions About Basement Insulation

R-value is the rating system used to rate insulation. The R-value varies from lowest to highest in terms of insulating power. R stands for resistance and represents the resistance of a material to heat flow or conduction. The higher the R-value number, the better the protection it offers against the passage of cold air.

Are there discounts for insulating a basement?

Yes, owners may be eligible for a tax credit until $500 or 10% of qualifying energy efficiency improvements.

Should an unfinished basement be insulated?

Insulating an unfinished basement depends on the house and the owner. In warmer climates, insulating an unfinished basement is not as necessary as in colder climates. If a house has a concrete foundation in a colder climate, insulating a basement is a good idea to reduce energy costs and alleviate potential water issues.


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