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Cost Of Attic Spray Foam Insulation In Pennsylvania

October 16th, 2023

5 min read

By Alexis Dingeldein

You know your attic needs insulation, and you'd like to invest in residential spray foam insulation. You just aren't sure if spray foam insulation is within your budget. Before reaching out to a professional, you would love to know a ballpark estimate of your project cost to determine how to move forward with your attic.

South Central Services has installed spray foam insulation in hundreds of homes. Pricing transparency is essential. We want to empower you to make basic calculations for yourself so you can be prepared and educated before getting an official quote from a professional.

By the end of this article, you will know:

  • What important questions to ask before calculating your sample estimate
  • How to calculate a sample estimate to install spray foam in your attic

Don't have time to read right now? Check out everything you need to know at a glance.

Factors Influencing The Cost Of Your Attic

There are two vital questions to ask before trying to calculate an estimate. These questions will determine what part of your attic is being insulated and what products are available to you. These questions will also dictate the measurements you must take for your calculations.

1. Will Your Attic Be Living Space?

Finished Attic Used As Living Space

Some families use attics for storage; others turn attics into home additions to expand their living space. Some families do not use their attic spaces at all.

When you consider how you will use your attic, ask yourself if you want to pay to condition the air in the attic. If you use the attic as an addition, you will want to maintain a temperature like the rest of your home. If you use the attic for storage, you may or may not need to maintain a temperature to protect what you are storing.

Attics that are considered living spaces need to insulate the attic's roof to insulate the attic from the outside air. Attics not being used as living space need to insulate the attic floor to protect the living space from temperature differences in the attic.

2. Do You Want Open Cell Or Closed Cell Spray Foam?

Both open cell and closed cell spray foam are options for attic installation. Closed cell is a more rigid foam, and open cell is a less rigid foam. The exact required depths will vary by climate zone, but as a general rule, closed cell spray foam requires fewer inches to be installed than open cell. Closed cell is also more expensive than open cell spray foam.

In our climate zone, closed cell spray foam only requires 3 to 6 inches of insulation, while open cell requires 7 to 12 inches.

If you want to install open cell spray foam to save money, you must ensure you can install it at the minimum number of inches required for your climate zone. When you contact a professional contractor, they may require using closed cell because building codes require more than the minimum.

Our service area is in Climate Zone 5, which includes southern Pennsylvania and portions of Maryland, Virginia, and West Virginia. Consult this map from the Department of Energy to determine what climate zone you live in.

What To Measure In Your Attic For Your Calculations

For some sample estimates, necessary measurements are as simple as length and width. Roofs are more complicated. Not only do you need to measure the length and width of the attic floor, but you also need to take roof measurements like height and pitch. The roof measurements are necessary to calculate the size of the gables. The gables are the triangular walls beneath a roof.

Attic Measurement Diagram

How To Calculate A Spray Foam Insulation Estimate

Spray foam insulation contractors create quotes from board feet. Board feet is a measurement calculated from square footage. While square feet only measure length and width, board feet is a three-dimensional measurement of length, width, and depth. See this visual to demonstrate.

square foot vs board footBoard feet are easy to find from square footage. You multiply square footage by the depth of insulation being sprayed. For example, if your space is 100 square feet and requires 3 inches of insulation, the space has a board feet of 300.

To make calculations as easy for you as possible, we have created the following chart with our rates and the ranges of insulation depth for our climate zone. If you do not live in Climate Zone 5, you will want to contact a local contractor for pricing information.

Attic Rates and Depths Chart

Sample Attic Floor Estimate

Sample Estimate Calculation for Attic Floor with Spray Foam Insulation

If you do not want to use your attic as a living space, this is the sample estimate for you. Learn how to calculate an example and use the dimensions of your attic floor to determine the average and highest costs for your attic.

1. Find Square Footage Of Attic Floor

This attic floor is 30 feet long and 20 feet wide, giving us 600 square feet.

[30 ft x 20 ft = 600 sq ft]

2. Find Board Feet From Square Feet

Our chart shows that the insulation depth necessary for attics can vary. Let's say this attic needs either 5 inches of closed cell or 10 inches of open cell spray foam.

The board feet for applying closed cell foam is 3,000 board feet.

[600 sq ft x 5 in = 3,000 bf]

The board feet for applying open cell foam is 6,000 board feet.

[600 sq ft x 10 in = 6,000 bf]

3. Find Price Using Board Feet Rate

After calculating the board feet, we can calculate the price.

The average closed cell spray foam cost is $1.45 per board foot. For 3,000 board feet, it will cost $4,350 to insulate this attic with closed cell spray foam.

[3,000 bf x $1.45 per bf = $4,350]

The average open cell spray foam cost is $0.50 per board foot. For 6,000 board feet, it will cost $3,000 to insulate this attic with open cell spray foam.

[6,000 bf x $0.50 per bf = $3,000]

Sample Roof Estimate

Sample Estimate Calculation for Attic Roofline with Spray Foam Insulation

If you want to use your attic as a living space, this is the sample estimate for you. Learn how to calculate an example and use the dimensions of your roof and gables to determine your attic's average and highest costs.

1. Find Square Footage Of Roof

This attic roof is 30 feet long, 20 feet wide, and 6 feet tall. The roof has a rake (or pitch) of 15 feet. Since we are insulating the gables and the roof, the total square footage is 1,020 square feet.

[30 ft x 15 ft x 2 = 900 sq ft]

[(20 ft x 6 ft x 2) / 2 = 120 sq ft]

[900 sq ft + 120 sq ft = 1,020 sq ft]

2. Find Board Feet From Square Feet

Our chart shows that the insulation depth necessary for attics can vary. Let's say this attic needs either 5 inches of closed cell or 10 inches of open cell spray foam.

The board feet for applying closed cell foam is 5,100 board feet.

[1,020 sq ft x 5 in = 5,100 bf]

The board feet for applying open cell foam is 10,200 board feet.

[1,020 sq ft x 10 in = 10,200 bf]

3. Find Price Using Board Feet Rate

After calculating the board feet, we can calculate the price.

The average closed cell spray foam cost is $1.45 per board foot. For 5,100 board feet, it will cost $4,350 to insulate this roof with closed cell spray foam.

[5,100 bf x $1.45 per bf = $7,395]

The average open cell spray foam cost is $0.50 per board foot. For 10,200 board feet, it will cost $5,100 to insulate this roof with open cell spray foam.

[10,200 bf x $0.50 per bf = $5,100]

The Bottom Line About The Cost Of Spray Foam In Attics

Insulating an attic with spray foam will cost thousands of dollars. Exactly how much your attic will cost depends on where you insulate and which product you use.

Making your attic a part of your conditioned living space is more expensive because the surface area being sprayed is greater. As long as you have the necessary depth in your attic, you can save some money using open cell spray foam.

Concerned about the cost of spray foam for your attic? Compare the cost of other insulation products for the attic.

Now that you know how much attic spray foam costs, your next step is to:

Alexis Dingeldein

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.