How Much Does Spray Foam Insulation Cost?

Spray foam insulation cost is one of the first questions asked when considering the best way to protect a building thermally. The advantages of spray foam insulation over other insulation types are well-known; its the cost of spray foam that is usually the biggest question.

Even though spray foam typically will cost more relative to alternatives, the energy efficiency and the energy savings over the life of the building are substantial.

Cost of Spray Foam Insulation

Spray foam insulation costs are figured in board feet since the thickness will vary depending on the specific building application and architect specifications.

Board feet in the insulation world are determined by simply taking the total square footage and multiplying it by the thickness in inches.

For example, 10 square feet of spray foam insulation with a 1″ thickness is considered 10 board feet. If that same 10 square feet of spray foam insulation were applied with a 3″ thickness, it would be 10 square feet x 3″ equaling 30 board feet of total spray foam insulation.

spray foam insulation cost

It isn’t easy to apply a spray foam insulation average cost to any project in any location. One of the reasons is that spray foam is installed by trained crews.

The labor costs involved in spray foam insulation will vary from region to region, and the specific conditions of each project will determine how long it will take.

While the spray foam material cost is fairly consistent from one town to the next, the cost of labor varies greatly.

This is the main reason homeowners and contractors must use caution when applying “unit pricing” to the project budget.

Closed Cell Spray Foam Insulation

Closed cell spray foam insulation typically has a higher overall cost than open-cell. This type of insulation can be applied at temperatures as low as 5 degrees F.

The properties of closed-cell insulation give it higher strength and greater impact resistance.

A great property of closed cell spray foam insulation is that its water-resistant and can act as a moisture vapor air barrier. Closed cell spray foam will control airflow and is much less permeable.

It’s typically found in below-grade applications, basements, or tough-to-reach areas, such as a crawl space.

Closed-cell spray foam also has a higher R-value than open-cell spray foam and other types of insulation like cellulose and fiberglass.

Closed-cell foam insulation has the capacity to reject water due to its closed cell structure. This type of spray foam is much harder when it dries and is more durable if it’s left exposed after construction is complete. It’s also mildew and mold resistant.

Does Closed Cell Spray Foam Add Structural Integrity?

As closed cell spray foam insulation hardens and dries, it transforms from a liquid to a rigid material. This process helps add structural integrity to walls and ceilings as it expands and adheres to the exterior sheathing, wall studs, trusses, nooks, and everything else it touches. The expansion doesn’t just stop air infiltration, but adds structural integrity to the building.

Will Closed Cell Spray Foam Insulation Kill Mold?

Yes, closed cell spray foam will limit mold growth by sealing off the two things mold requires to grow: oxygen and moisture. Existing mold will become dormant because it will lack additional oxygen and moisture, and make it very difficult for future mold growth to occur.

Closed Cell Spray Foam R-Value

Closed cell spray foam insulation is a popular choice because of its high R-Value of 6-7 per inch. With open cell spray foam only getting 2.2-3.5 R-Value per inch, closed cell remains the favorite among architects, building owners, contractors, and homeowners for their home insulation projects.

Open Cell Spray Foam Insulation

Light-density, open-cell spray foam insulation is common in above-grade wall cavities, attics, and underside of roof decks. Open-cell foam has moisture permeability properties to encourage bi-directional drying of wall assemblies.

Open-cell spray foam insulation is also much more cost-effective than closed-cell. While it has lower R-values than closed-cell, it’s much more affordable.

Open-cell insulation is also easier to work with because it doesn’t dry to such a hardened state as closed-cell foam.

Benefits of Spray Foam Insulation

Numerous benefits make spray foam insulation the preferred material for nearly any construction project. Many new homes use spray foam insulation within the building envelope wall stud cavities, at the rim joist, attic floor, and roof trusses for greater thermal protection over fiberglass.

The higher costs for spray foam over fiberglass batt insulation are offset by lower future heating costs, cooling costs, and energy bills over the life of the building.

You might be wondering why the energy star savings are so great with spray foam and what makes it so much more desirable over fiberglass insulation.

One of the primary benefits of spray foam is the gradual expansion of the insulation after it’s sprayed and applied to a certain area.

The expansion fills small cracks, holes, and gaps. This prevents heat loss in the winter and keeps cool air in during the summer.

Another benefit to spray foam insulation that is often overlooked is that spray foam acts as a vapor barrier and its thermal properties. This eliminates the need for an interior air seal vapor barrier typically applied to the inside of wall studs and trusses behind drywall.

The expanding spray foam prevents air leaks and removes any worry of a poly vapor retarder or vapor barrier tearing or installing incorrectly.

How to Install Spray Foam Insulation

Installing spray foam insulation is fairly simple for exterior walls and stud cavities off the ground in a new construction project.

Installers spray the desired thickness to the backside of the exterior sheathing, accounting for the expansion of the material. Hence, it fits snugly, leaving no gaps or cracks on the exterior and providing excellent energy efficiency.

Spray polyurethane foam insulation (SPF) can be more difficult at roof structures, hard-to-reach crawl spaces, HVAC duct penetrations, roof parapets, high walls, and hidden nooks and crannies.

Renovation projects typically will have a higher cost on average to compensate for unknown conditions.

Spray foam in an existing building might also result in higher costs than new construction because special care might be needed around finished areas of the building.

For small projects, a two-component high density polyurethane quick-cure closed cell ‘Froth-Pak’ is a popular choice.

For roughly $800, you get two canisters of medium density spray foam sealant covering nearly 1,000 board feet of area. These do-it-yourself products are highly regulated and conform to low Global Warming Potential (GWP) guidelines.

What is the Difference Between a Board Foot and a Square Foot?

A Board foot is measured with three dimensions: Length, width, and thickness. A square foot is simply an area with only two dimensions: length and width.

One board foot contains 144 square inches. That’s 12 inches in length, by 12 inches in width, by 1 inch thick. A shortcut to calculate a board foot, multiply thickness, by width, by length. Then divide by 144.

Another way to think about board foot measurement is one cubic foot equals 12 board feet.

Superior R-Value

The high performance R-Value of spray foam insulation is far superior to its fiberglass batt competition. In fact, the average R-value for fiberglass and cellulose insulation is somewhere around 3 to 4 per inch of thickness.

The average R-value for closed-cell insulation is nearly double that, somewhere in the neighborhood of 6 to 7 per inch of thickness.

spray foam insulation cost

Things to Consider When Pricing Spray Foam

It’s also important to consider that certain project conditions will incur additional costs for installing spray foam. These project-specific conditions are taken into account when the pricing is compiled.

When projects go over budget, many times it’s because of the job site-specific conditions that were not taken into account, which sends the project costs soaring beyond what was originally planned.

Rather than using inaccurate square foot pricing for spray foam insulation that might vary greatly from what your project will actually require, it’s a good idea to talk with a local spray foam contractor.

Find one of the best spray foam insulation contractors in your specific market, and call or email them with details about your project.

They will provide job-specific pricing, and even data sheets detailing exactly what spray foam they would recommend for the job.

The best spray foam contractors will have project estimators on staff to assist potential customers on budgetary price ranges.

Although the numbers they give over the phone might not be set in stone, they will be much closer and more realistic to your specific project.

Spray Foam Insulation Cost Calculators

There are some pretty amazing spray foam insulation cost calculators out there. So many, in fact, you could spend an entire weekend surfing between cost calculators for your spray foam project, and you still wouldn’t see them all.

Cost calculators are neat, but it’s important to understand the inputs, as software is only as good as what the operator tells it to do.

Some spray foam cost calculators even include estimated savings in energy costs compared to other products.

Here are a few links to helpful spray foam cost calculators, along with a board feet calculator from

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