How Much Does Spray Foam Insulation Cost

How Much Does Spray Foam Insulation Cost in 2021

Spray foam insulation costs vary depending on a few different factors. The type of spray foam you choose, how much insulation you need, whether you’re insulating a new or existing home, and whether or not you hire a professional will all affect the final cost.

So, what’s the average cost for spray foam insulation? Spray foam insulation costs can be anywhere from $0.25 to $3 per board foot.

Let’s compare the two types of spray foam insulation, their pros, and cons, costs, and decide whether it’s the best choice for your home.

Closed-Cell vs. Open-Cell Spray Foam Insulation: Costs & Differences

Closed-cell foam consists of confined cells. That structure leads to a high-density, rigid foam. It has an R-value of 6.25 per inch, making closed-cell spray foam one of the most efficient home insulation materials. Because it expands less than open-cell foam, it takes more material to establish an air barrier around spaces. The upside is that you can fit more insulative foam in limited spaces to maximize the insulation in a building.

Because of closed-cell foam’s high density and R-value, it can also double as a vapor barrier, preventing moisture that can lead to mold and rot. Due to its moisture resistance and insulative properties, closed-cell spray foam is the go-to choice for foam roofing.

Closed-cell spray foam insulation can cost anywhere from $0.90 to $3 per board foot.

On the other hand, open-cell spray foam insulation generates a more porous, low-density foam that expands to a larger size upon application. It requires significantly less material per board foot, leading to its lower costs compared to closed-cell. Open-cell foam is ideal for areas that are difficult to reach because of its large expansion area and ability to minimize air leaks.

Open-cell spray foam insulation can cost anywhere from $0.25 to $1.50 per board foot.

Pros & Cons of Using Spray Foam Insulation

Is spray foam a good insulator? Let’s look at the advantages of spray foam insulation:

  • Lower Utility Bills—Spray foam insulation has one of the highest R-values of any insulation option, meaning it can improve the energy efficiency of your home. 
  • Tax Savings—In some cases, using spray foam insulation will help you save during tax time. If the installation comes qualified as an energy-efficient improvement, you may be eligible for an energy tax credit.
  • Seals Gaps—Other than insulating, spray foam air seals gaps as it expands, sealing otherwise difficult to access gaps and cracks. This is why spray foam insulation is arguably the best choice for areas like crawl spaces and attics.
  • Vapor Barriers—When using closed-cell spray foam, the insulation also acts as a vapor barrier, helping prevent moisture linked to structural deterioration and mold.
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What are the disadvantages of spray foam insulation? Let’s look at the downsides of using spray foam insulation:

  • Higher Costs—All of spray insulation foam’s advantages come with higher costs than traditional insulation options like fiberglass batt, which can be half the cost for installation


  • Health Risks—Exposure to spray foam insulation (before it cures) can cause respiratory, eye, and skin irritation. Many manufacturers recommend that you vacate the property for 24 hours after insulation installation.
  • Not DIY-Friendly—While you can find spray foam insulation at your local hardware store, you’ll need to know how to mix and install it, along with access to the right chemicals and necessary equipment.

Related: 7 Signs You Need Roof Repairs or Replacement

Calculating Spray Foam Insulation Costs

Board feet is the measurement used by professionals to determine how much spray foam insulation your property will need. Because spray foam can be applied in different depths, this measurement takes into account both square footage and the foam thickness.

Typically, one board foot refers to a 1-foot by 1-foot space of 1-inch thick foam insulation. That means that one board foot is equal to 1/12th of a cubic foot.

There’s an easy way to calculate how many board feet of spray foam insulation you’ll need: 1 square foot * 1 inch = 1 board foot. For example, if you wanted to insulate 100 square feet of the wall and ceiling in a building with 1-inch thick insulation, you would need 100 board feet.

But what if you need thicker insulation due to living in a colder climate? Simply replace the 1-inch in the equation with the desired thickness. So, looking at the same example, if you wanted a 3-inch thick layer of insulation, you would calculate it like this: 100 square feet * 3 inches = 300 board feet.

The cost per board foot will change depending on which type of spray foam insulation you decide to go with, but the board foot calculation will remain the same.

Other Factors that Affect Spray Foam Insulation Costs

We talked about the spray foam insulation costs differences between open and closed-cell foam, and the area that you are insulating determines which one you’ll likely use. For example, basements and areas where water can be a concern usually warrant the use of closed-cell foam because of its moisture resistance. Qualified contractors can advise you about which type of spray foam will be the best for different areas of your home.

When it comes to wall insulation, the costs vary considerably between existing homes and new ones. Spray foam insulation in new construction is less expensive and easier to install because the installers can apply the insulation without the obstruction of drywall and the exterior wall. Finished structures make spray foam insulation more complicated because the outer and inner walls are already covered, meaning that the installers need to create holes to access wall cavities between the studs. Overall, expect to spend more if you’re insulating an existing building.

Is Spray Foam Insulation the Right Choice for Your Building?

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While not the cheapest option, spray foam insulation is one of the best choices for roof and building insulation. Not only does it effectively seal gaps, provide an exceptional R-value per inch, and adhere well to surfaces, it can reduce your utility bills over time, helping offset the higher initial costs.

Want to maximize the energy efficiency of your home and insulate your roof with spray foam insulation? Get in touch with our roofing experts today!

Related: Roof Consulting, Repair, and Replacement FAQs

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