How Spray Foam Insulation Is Made

If you’ve seen footage of spray foam expanding, you’ve probably thought, “Wow. That’s pretty cool.” Seeing foam expand can be satisfying to watch. But now you’re wondering how that expansion happens. How is that foam created? What exactly is happening?

South Central Services has installed spray foam insulation in hundreds of homes. We are passionate not only about spray foam but about educating people on how spray foam works.

By the end of this article, you will understand:

• How spray foam insulation is created from start to finish
• What makes spray foam insulation a safe product
• Problems that could cause the foam to fail
• Whether you could install spray foam insulation yourself

The Stages of Spray Foam Insulation

Most insulation products are manufactured, tested, sold, and installed. Spray foam insulation is different. The ingredients of spray foam are manufactured, tested, and sold. The finished product of spray polyurethane foam insulation is manufactured during installation.

Spray polyurethane foam insulation (SPF) goes through many stages to become a finished product in someone’s home or building. Let’s break down how spray foam is created from beginning to end.

Stage 1: Manufacturers Design and Test Spray Foam Components.

Spray polyurethane foam is created from the chemical reaction of two chemical components. Manufacturers must create these chemical components first. The technical names for these components are isocyanate and polyol blend. Commonly, the components are referred to as A-Side and B-Side.

Manufacturers spend years designing and testing these chemical components. Their testing answers questions like:

• How much foam will be created?
• Does the foam apply and expand smoothly?
• What are the conditions for this foam to adhere?

After testing, spray foam components can be made available for sale to contractors. The amount of time spent on research, development, and testing will vary by manufacturer. Many companies spend about a year preparing products for the market. Some manufacturers have spent as long as three years perfecting the components.

Stage 2: Qualified Contractors Purchase Spray Foam Components.

Manufacturers most commonly sell spray foam components in 55-gallon drums. Spray foam contractors purchase these drums of material to install. To install any spray foam, a minimum of one 55-gallon drum of A-Side and one 55-gallon drum of B-Side is required.

We noted that qualified contractors are the ones purchasing the foam. In this sense, a qualified contractor has the necessary equipment to apply the foam correctly. This contractor would own a spray foam rig, including a spray hose, spray gun, and monitoring equipment.

The chemical components come with manufacturer guidelines explaining conditions where the foam can be successfully applied, as well as the technical specifications.

Stage 3: Spray Foam Components Are Prepped On Site.

The spray foam components must be on-site to manufacture the spray polyurethane foam. The same spray foam rig which contains the equipment is used to transport the 55-gallon drums to the building. When the rig arrives to begin spraying, residents and pets are required to evacuate the space. Then, the component preparation begins.

The liquid chemicals are portioned and heated inside the spray foam rig to prepare them for their chemical reaction. The chemical reaction will occur in a 1:1 ratio. Manufacturers sell the components in a 1:1 ratio, so this step is critical to maintaining this ratio as the chemicals move from the drums.

After being heated and portioned, the liquid chemicals travel through the spray hose. The spray hose contains three inner hoses: a hose for the A-Side, a hose for the B-Side, and an air hose.

Stage 4: The Chemical Reaction Occurs.

The liquid chemicals have been heated and pressurized. After leaving the spray gun, both chemicals become atomized. Atomized means the liquids turn into tiny uniform particles, allowing them to mix effectively.

When the chemicals meet in this state, the chemical reaction begins. The chemicals are already hot, but more heat is created as they react. This type of chemical reaction is known as an exothermic reaction because it creates heat as a byproduct.

Stage 5: The Finished Spray Foam Insulation Cures.

Immediately after spraying, the spray foam is warm to the touch. Spray foam is only considered a finished product after it has cured. As a general rule, spray foam insulation takes between 12 and 24 hours to cool and cure, depending on the application, ventilation, and foam type.

What Can Go Wrong During These Stages?

At the end of these stages, a stable on-ratio foam should have adhered to the substrate, providing an airtight seal. However, many factors could change the outcome of the foam.

Problematic Components

The industry standard is a minimum of a year of research and development before sending components to market. Some manufacturers spend less time before selling their chemicals. Cheaper foam components may also have lower-quality ingredients or fillers. At South Central Services, we spray the highest-grade foams.

Foam components of a lower quality or with a less developed formula can make the application process difficult for the contractor. When the foam is not easy to work with, it can result in failed foam or wasted material.

Contractor Error

You can think of spray foam like baking and cooking. Baking is a science that requires exactness for the right outcome. Cooking is often more creative. When we approach baking with the same attitude as cooking, the result is usually flawed or inedible.

Similarly, the chemical reaction to create spray foam is science. Manufacturer guidelines are like a recipe for spray foam insulation. If a contractor applies foam outside those manufacturer guidelines, the result will be wrong. Contractor error is the most significant potential variable in spraying foam.

Let's examine the top three installer errors that can lead to ineffective foam.

1. Wrong Temperature

The ingredients for spray foam insulation must be heated to a particular temperature. This temperature is determined in Stage 1 during manufacturer testing. When the components are overheated, the foam can char or burn. Burned foam is an unacceptable and ineffective result.

2. Off-Ratio Foam

We mentioned earlier that spray foam is created in a 1:1 ratio. In a chemical reaction involving components with health risks in their raw form, all the chemicals must react. As long as all the raw chemicals react, they are no longer in their raw form and pose no health risks.

If the foam is off-ratio, then some amount of one chemical is left in its raw form. Continuous off-gassing from leftover chemicals could lead to respiratory problems. Additionally, off-ratio foam is not an effective insulation product. It may fail to adhere correctly or to create an airtight seal.

Off-ratio foam will only occur if equipment malfunctions in Stage 3. No equipment can last forever, so off-ratio foam is not contractor error. However, failing to recognize the signs of off-ratio foam and not immediately removing it is contractor error.

The warning signs of off-ratio foam are subtle and would be difficult for a homeowner to accurately recognize. The most likely indicators are a very strong odor 48 hours after spraying, or a tacky stickiness in the foam. If you have spray foam and suspect it could be off-ratio based on these criteria, contact your contractor for a diagnosis.

3. Ignoring External Factors

When manufacturers write their guidelines for their spray foam components, they include helpful information about many kinds of external factors. Guidelines could include the range of acceptable temperature and humidity levels of a substrate. At certain temperatures or levels of moisture content, the foam will not adhere. Manufacturers communicate this information based on the testing done during Stage 1.

One example of an important external factor is the weather. In southern Pennsylvania, spray foam insulation can be installed most days of the year. However, there are days during the winter that are not suitable to install spray foam.

The foam is likely to fail if the contractor ignores these types of external factors.

Could I Install Spray Foam Insulation Myself?

Many companies sell do-it-yourself spray foam kits. While you could install spray foam yourself, the likelihood of error is high. DIY spray foam is difficult to monitor and control. Not only would you be at a disadvantage without detailed manufacturer guidelines, but you would also be unable to control the variables which could ruin your foam.

Spray foam insulation is a premium product that offers premium performance, but only if it is installed correctly. DIY spray foam will not provide this performance because it cannot be monitored.

The Bottom Line About Making Spray Foam Insulation

Spray foam insulation is a cool product that can be fun to watch. But spray foam is also a complex product that requires tested components, trained contractors, and expensive equipment. Going from liquid chemical to polyurethane foam is a chemical reaction. Like most science experiments, too many variables will change the final result.

If you’re interested in spray foam for your project, learn more about the cost of spray foam and how to find a qualified contractor.