# Open Cell Spray Foam Insulation Cost

March 13th, 2024 | 5 min read

You want spray foam insulation for your project but don’t know how much it will cost. You’ve heard that spray foam insulation is very expensive. Even if open cell spray foam is the less costly of the two types of spray foam, will it still be too pricey to install?

South Central Services has insulated hundreds of homes with spray foam. Spray foam insulation is one of the most expensive insulation products available. We want to empower you to calculate a rough estimate of your project before reaching out to a professional.

By the end of this article, you will understand:

- The cost per board foot for open cell spray foam
- Why cost per square foot is different for every application
- How to estimate the cost of open cell foam for several project types

## How Much Does Open Cell Spray Foam Cost Per Square Foot?

Open cell spray foam insulation is priced by board foot instead of square foot. The cost per square foot depends on the depth of insulation being installed. Some applications require only 3.5 inches of open cell foam, while others can have as much as 12 inches installed!

A board foot is a more straightforward and consistent way of measuring insulation cost. Rather than having a rate per square foot for every application, you can calculate the rate for your project based on square footage and the depth of insulation needed. The diagram below illustrates the difference between board feet and square feet.

You’ll multiply the square footage by the number of inches of insulation needed to find board feet from square feet.

An exterior wall might need only 4.5 inches of open cell spray foam. If the wall is 120 square feet, the board feet of the project would be 540.

A roof application needs an average of 10 inches of open cell spray foam. If the roof is 1,000 square feet, the board feet of the roof would be 10,000 board feet.

Open cell spray foam insulation costs between $0.25 and $0.75 per board foot.

Applied to these examples, the average cost to insulate that exterior wall would be $270. For that particular roof, the average cost would be $5,000.

### Do I Need To Calculate Cost Per Board Foot?

You don’t have to calculate the cost per board foot to estimate the cost of your project. You can use our board foot rates to find a price per square foot for each type of application.

However, understanding the cost per board foot is in your best interest as you continue to do additional research. Not only do board foot rates eliminate the need to remember several sets of rates, but they are also a standard across the industry. As you research other insulation types, you will see their coverage represented by board feet rather than square footage.

## Sample Open Cell Spray Foam Estimates

Open cell spray foam insulation is useful for above-grade projects. Compared to closed cell spray foam, open cell does not have as many application possibilities in our climate zone. However, open cell spray foam offers sound attenuation capabilities, which closed cell spray foam does not.

In the following sections, we will give examples of how to calculate estimates for open cell spray foam. Specifically, we will cover:

- Exterior walls
- Basement ceilings
- Attic floors
- Attic ceilings

Each example will include subjective rates for the cost per square foot. However, we do encourage you to learn the board foot rates. The most accurate way to calculate an estimate is with board feet.

Let’s examine these in more detail.

### Estimate For Open Cell In An Exterior Wall

In an exterior wall, the open cell cost per square foot would be between $1.75 and $2.75, with a maximum cost per square foot of $4.13. We can calculate this rate based on the board foot rate and the insulation depth needed in exterior walls.

- Depth of open cell spray foam for exterior walls: 3.5 to 5.5 inches
- Rate of open cell spray foam per board foot: $0.25 to $0.75

For the following example, we calculated two costs per square foot. Using the average amount of open cell insulation needed in exterior walls, we calculated at the lowest and highest end of our cost per board foot range.

The cost to insulate this exterior wall with open cell spray foam can range anywhere from $170 to $507. The price could also be lower or higher with more or less open cell spray foam.

### Estimate For Open Cell In A Basement Ceiling

In a basement ceiling, the open cell cost per square foot would be between $2.50 and $5.00, with a maximum cost per square foot of $7.50. We can calculate this rate based on the board foot rate and the insulation depth needed in basement walls.

- Depth of open cell spray foam for basement ceilings: 5 to 10 inches
- Rate of open cell spray foam per board foot: $0.25 to $0.75

For the following example, we calculated two costs per square foot. Using the average amount of open cell insulation needed in a basement ceiling, we calculated at the lowest and highest end of our cost per board foot range.

The cost to insulate this basement ceiling with open cell spray foam can range anywhere from $432 to $1,296.

### Estimate For Open Cell In An Attic Floor

In an attic floor, the open cell cost per square foot would be between $4.35 and $8.70, with a maximum cost per square foot of $10.50. We can calculate this rate based on the board foot rate and the insulation depth needed in basement walls.

- Depth of open cell spray foam for attic floors: 7 to 12 inches
- Rate of open cell spray foam per board foot: $0.25 to $0.75

For the following example, we calculated two costs per square foot. Using the average amount of open cell insulation needed in an attic floor, we calculated at the lowest and highest end of our cost per board foot range.

The cost to insulate this attic floor with open cell spray foam can range anywhere from $1,500 to $4,500.

### Estimate For Open Cell In An Attic Ceiling

In an attic ceiling, the open cell cost per square foot would be between $4.35 and $8.70, with a maximum cost per square foot of $10.50. We can calculate this rate based on the board foot rate and the insulation depth needed in basement walls.

- Depth of open cell spray foam for attic ceilings: 7 to 12 inches
- Rate of open cell spray foam per board foot: $0.25 to $0.75

For the following example, we calculated two costs per square foot. Using the average amount of open cell insulation needed in attic ceilings, we calculated at the lowest and highest end of our cost per board foot range.

The cost to insulate this attic ceiling with open cell spray foam can range anywhere from $2,550 to $7,650. The price could also be lower or higher with more or less open cell spray foam.

## The Bottom Line About Open Cell Spray Foam Costs

Open cell spray foam is the more affordable of two types of spray foam insulation. Open cell spray foam cannot be used for every application but is useful for above-grade projects and sound attenuation purposes. The cost per board foot for open cell spray foam ranges between $0.25 and $0.75.

The cost per square foot varies depending on the type of project, because every application requires a different depth of open cell spray foam to meet building codes.

Now that you understand how much open cell spray foam costs, your next step is to:

Alexis has been fascinated by spray foam insulation since 2018. When she isn’t thinking about insulation, Alexis is geeking out over storytelling and spreadsheets.

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