How To Insulate An Attic With Spray Foam

You want to have your attic insulated with spray foam. The problem is, you don’t know how. Can you do this yourself, or do you need to hire a professional contractor? What does the process look like? How much will it cost you?

South Central Services has installed spray foam insulation in hundreds of homes. We are often sought after for attic insulation around Franklin County because of the benefits an insulated attic can provide. This article will share our process for insulating attics with spray foam.

After you have finished reading, you will know:

• What questions you need to answer before installing anything
• Where spray foam can be installed in an attic
• Which spray foam products are available for attic insulation
• How much time and money an attic installation will cost
• Whether you can successfully install spray foam in your attic yourself

What Do I Need To Know Before Installing Spray Foam In The Attic?

Before installing spray foam in the attic, you should know two things. First, whether or not the attic is a main source of energy inefficiency. Second, if you want your attic to be a part of your conditioned living space.

1. Do I Need Attic Insulation?

If your house is overheated and uncomfortable in the summertime, lack of attic insulation is likely the culprit. The high temperatures in the attic push through the attic floor into the living space. The HVAC ductwork in the attic is likely overheated, forcing the HVAC system to work harder to maintain consistent temperatures.

In nine of ten homes, attics need more insulation.

2. Do I Want To Use My Attic As A Conditioned Living Space?

The answer to this question will determine whether you are insulating the attic floor or your roofline.

You will insulate your attic floor if you do not want to use your attic as a conditioned living space. By insulating the floor, the excess heat in the attic will not invade the rest of the home that you pay to cool. The only complication of this that could be at play is your HVAC ductwork, which may still overheat and contribute to the load on the HVAC system.

You will insulate your roofline if you want to use your attic as a conditioned living space. By insulating the roofline, the heat of the outside air will be prevented from entering the attic. This method supports your HVAC system by keeping the HVAC ductwork at the same temperature as the rest of your home.

There is no situation where you would insulate both the attic floor and the roofline. If you insulated both the floor and the roofline, you would create an isolated climate, completely separate from the living area of your home.

Will you only benefit from spray foam insulation in the attic during the summertime? No, spray foam attic insulation is useful year-round. You may be able to see the benefits of attic spray foam more clearly in the summertime because of the heat transfer it prevents. But spray foam insulation also prevents air transfer by creating an airtight seal. In the wintertime, spray foam in the attic keeps the hot air you pay for inside the house.

Bonus: Do I Need To Remove Existing Attic Insulation?

In order for spray foam insulation to create an airtight seal, existing attic insulation must be removed before spray foam is installed.

Which Types Of Spray Foam Can Be Installed In Attics?

Spray polyurethane foam insulation comes in two types: closed cell and open cell. Closed cell spray foam has more comprehensive application options than open cell does. However, both closed cell and open cell spray foam are options for attic applications.

Open cell spray foam can be installed on the attic floor or roofline. Because open cell is a low-density product, it will be installed with a greater depth. A depth of 7 to 12 inches of open cell is standard in attics and roofs. Open cell spray foam at these depths will create an air barrier but cannot create a vapor barrier. Additional vapor retardant coatings must be added on top of open cell foam.

Closed cell spray foam can be installed on the attic floor or roofline. Closed cell will be installed at a more shallow depth because of its higher density. Standard depths for closed cell spray foam in attics and roofs are 3 to 6 inches deep. Closed cell foam will create both an air barrier and a vapor barrier at these depths.

How Long Does Installing Spray Foam In An Attic Take?

The time to complete an attic installation will vary depending on the amount of preparation work and the project size. Installation could be as short as a day for a small attic where existing insulation has already been removed. An example of a small attic floor would be around 700 square feet.

For larger projects or projects where existing insulation still needs to be removed, installation time could take as long as two or three days. An example of a larger attic floor would be 3,000 square feet or more. Below is an example of a large attic where existing insulation had to be removed.

How Much Does Installing Spray Foam In An Attic Cost?

Installation costs will vary depending on all the factors we have discussed.

As a general rule, insulating the attic floor is less costly than insulating the roofline. The attic floor will have fewer board feet than the roofline, so the raw material cost for the floor will be lower. The attic floor only includes the length and width of the attic, while the roofline includes the both sides of the roof as well as the roof gables.

The type of spray foam used to insulate your attic will impact the cost.

Closed cell spray foam could cost as much as $10 per square foot. Open cell spray foam could cost as much as $9 per square foot. (These calculations are derived from our highest rates and the greatest depths of insulation necessary for attic applications.)

The size of your project will also impact the cost of insulating your attic with spray foam. For a smaller attic, the cost may be around $4,000. For a larger space, costs could reach as high as $17,000.

You can calculate your own sample estimate for your attic using our pricing guide.

We Do Not Recommend DIY Spray Foam For Your Attic. Here's Why.

Spray foam insulation is a premium product. Not only can spray foam insulate your home, but it can also provide an airtight seal. This two-in-one application makes homes more comfortable and energy efficient.

Seeing the premium product price tag can be daunting. We understand you may want to complete this project yourself to save money.

However, we cannot recommend DIY spray foam for attic applications. Here are the top four reasons why we do not recommend DIY spray foam in the attic.

1. You'll Need To Purchase A Large Quantity Of Raw Materials.

If DIY spray foam kits have any reliable place in the home improvement world, it is for small-scale air-sealing projects. In these situations, homeowners can save money and get a decent ROI for their investment costs.

Attic spaces do not qualify as small-scale air-sealing projects. Even for a small attic, the number of DIY kits you must purchase cancels out any cost-savings you might enjoy.

For example, a standard DIY kit from a home improvement store costs $400 and covers 200 board feet. Even if your attic only needed 3 inches of insulation, you could only insulate a maximum of 66 square feet with one kit.

DIY spray foam kits will not provide significant cost savings for attic applications due to the quantity of raw materials needed.

2. You'll Need To Invest In Ventilation Equipment And PPE.

When a professional contractor insulates an attic, they take specific precautions to ensure proper ventilation while manufacturing and installing the spray foam.

Spray foam insulation is a unique product manufactured on-site through a chemical reaction. The chemical reaction creates a byproduct called off-gassing, which is toxic to inhale. To protect themselves while they spray, contractors wear suits and respirators. They also set up ventilation systems in the attic to direct off-gassing fumes outside the home.

Not only would you need to acquire a ventilator to install spray foam yourself, but you will need to determine how to ventilate your attic to direct off-gassing fumes outside. Our team uses ventilation fans with flexible ducts, which look like big tubes, to direct air into or out of the attic space. Failure to set up proper ventilation can send these fumes into your home, where they can absorb into fabrics and linger.

3. You May Face Frustrating Accessibility Issues While Spraying.

Every attic is different, but there are potential accessibility issues when spraying a roofline. If your roof is very tall or has an odd shape, you may struggle to cover and insulate all attic areas effectively.

A professional contractor frequently solves these kinds of accessibility challenges. The installation team can find ways to ensure the foam is installed correctly, at consistent depths, in every area it must be installed.

4. Your DIY Spray Foam Kits Have A Likelihood Of Failure.

Spray foam insulation is deceptively complex. If you watch a video of it being installed online, it looks as simple as pointing and spraying. It is easy to think you can install spray foam yourself without complications.

Spray foam is created through a chemical reaction, and that chemical reaction depends on the consistency of several variables. Any of these variables can impact the success of the foam. DIY spray foam kits do not provide the control or monitoring tools to keep these variables constant.

Without these monitoring tools, spray foam insulation can fail. Failed spray foam insulation should never be left in someone’s home and can be difficult to remove. If you install spray foam in the attic yourself and something goes wrong, you will most likely have to hire professionals to remove and replace the insulation.

The Bottom Line About Insulating Attics With Spray Foam

Lack of attic insulation is one of the main culprits behind heating and cooling struggles in a home. Insulating your attic with spray foam can increase your energy efficiency, make your home more comfortable, and even improve your air quality. These benefits are due to the 2-in-1 feature of spray foam as an insulation and an air-sealing product.

It can be expensive if you want to insulate your attic with spray foam. Costs will depend on the size of your attic, where in your attic you are insulating, and which spray foam you insulate with.

Now that you know how attics are insulated with spray foam, your next step is to:

• Calculate an estimate of spray foam insulation for your attic
• Discover the benefits of insulating your attic with spray foam
• Learn how professional contractors install spray foam in attics