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6 Problems With Spray Foam Insulation Explained

April 8th, 2024 | 4 min read

By Alexis Dingeldein

You've likely encountered several claims about spray foam as you've researched the insulation. A quick Google search leads to many concerns, including mold, toxic air quality, environmental worries, and more. Are these claims about spray foam insulation true?

South Central Services has insulated hundreds of homes with spray foam. The truth is that spray foam can have problems, but almost every problem is caused by installation error.

By the end of this article, you will know:

  • The six most common concerns about spray foam insulation
  • Why these problems occur and how to avoid them

Claim: Spray Foam Insulation Can Lead To Mold

It is true that improperly installed spray foam can lead to mold. Spray foam insulation isn't a miracle product. Spray foam is also not a one-size-fits-all product.

When constructing a building, every building material has to work together to make the structure function. The features of spray foam do not override the rules of building design.

One example of improper installation that can lead to mold is installing spray foam in a leaky basement or roof. Spray foam insulation is not a waterproofing product. If spray foam is installed in a basement or an attic that leaks, mold could grow.

Mold growth on the walls in the corner of a home.

Another example of improper installation is the use of the wrong type of spray foam. Climate zone helps to determine which type of spray foam to use. Homeowners in southern Pennsylvania have to be concerned about vapor transfer. The further south you travel, the less relevant vapor barriers become.

Any insulation improperly installed can cause mold or mildew issues. This problem is not isolated to spray foam and indicates a need for a qualified installer.

Claim: Spray Foam Insulation Can Have A Bad Odor

If your spray foam insulation has a strong odor, that is an indicator that your spray foam was installed off-ratio. Professional contractors should never leave off-ratio foam as a finished product in a home. Contact the installer immediately if you notice a strong odor so they can come to examine their work.

How can spray foam be made off-ratio? Spray foam insulation is created through a chemical reaction and is manufactured on-site. The chemical reaction does have several variables that must be monitored and kept within certain ranges. Contractors spend tens of thousands of dollars on monitoring equipment to prevent foam from going off-ratio.

Residents and pets are not allowed on-site during spray foam installation. The chemical reaction to create spray foam does have a natural byproduct called off-gassing. Residents are invited back to their space once these fumes have dissipated.

When a contractor first arrives, the foam insulation has yet to be made. Once the contractor leaves, all that should remain is a safe spray foam product.

A qualified professional will deliver a safe, on-ratio, and inert product.

Claim: Spray Foam Insulation Can Lead To Termite Damage

It is true that termites can burrow through spray foam insulation. If you live on a property that has faced termite damage in the past, it is essential to know this.

Termite damage in the wood door of a home.

However, it is also important to know that no insulation is pest-proof. Every insulation has its drawbacks regarding pests, whether it's considered a nesting material, a food source, or something termites can burrow through.

You should invest in pest control measures no matter what insulation you choose. Insulation alone is not a pest control measure.

Some insulations can contribute to pest-infestation prevention, but no insulation is pest-proof.

Claim: Spray Foam Insulation Is Too Airtight

There is no such thing as being too airtight. The fear behind air-sealing a home is that a home won't have proper ventilation. In reality, air-sealing allows you to ventilate your home in the most efficient way.

When a home is not airtight, air ventilates in three ways: infiltration, natural, and mechanical.

Natural ventilation occurs when doors and windows open. Mechanical ventilation is facilitated by HVAC equipment like air conditioners, HRVs, ERVs, and ductwork. Infiltration happens when air leaks uncontrollably through leaks in your home.

When a home is airtight, the air still ventilates. However, it is only ventilated through natural and mechanical ventilation. Doors and windows still open. HVAC equipment still ventilates and circulates air. The only thing that changed is that air cannot leak uncontrollably.

A person opening a window or door in their home to let in fresh air.

What happens when air leaks uncontrollably? The quality of that random air defines the quality of the air in your home. If it's hot outside, it will be warmer inside. If it's freezing out, it will be colder inside. If it's humid outside, your home will feel sticky. If the air quality outside is poor, so will your air inside be poor.

An airtight seal is not the enemy of ventilation. It is the first step in maximizing the efficiency of your ventilation. When your ventilation is efficient, you spend less on maintaining your HVAC equipment.

Claim: Spray Foam Insulation Will Shrink Over Time

It is true that improperly installed spray foam insulation can shrink over time. However, stable spray foam insulation will not shrink over time.

Spray foam insulation shrinking or pulling away from the substrate indicates that the spray foam is unstable.

Unstable spray foam insulation should never be left in someone's home as a finished product. Shrinking foam indicates some form of installation error. That installation error could be either off-ratio foam or foam that was sprayed when it was too cold.

Does that mean that foam sprayed in the winter will be unstable and shrink? Not necessarily. Competent spray foam contractors know spray techniques that help foam adhere in colder temperatures. Manufacturers also design spray foam components for winter months to prevent this type of failure.

A competent spray foam contractor will also measure the temperature of the substrate before spraying. This measurement can help determine if the weather conditions or temperature are unfavorable and cannot be remedied. In these cases, your contractors should not push forward with installation.

Claim: Spray Foam Insulation Is Not Eco-Friendly

It is true that spray foam insulation cannot be recycled. Spray foam is also made of plastic. These are two common reasons cited for spray foam not being environmentally friendly.

We understand these concerns. When you think about the lifecycle of spray foam insulation, you have to ask what to do with it when the product is no longer useful.

Luckily, spray foam insulation installed in buildings is meant to be a permanent product. The goal of spray foam is to last as long as a structure and to provide an airtight thermal barrier for the building. Spray foam may not be recyclable, but it is one of the most energy-efficient insulations.

Is it more critical for insulation to lower energy consumption over the lifetime of a building or to be recyclable at the end of a building's lifetime? That's a question that everyone must answer for themselves.

Spray foam insulation can break down when exposed to UV light. While spray foam cannot be reused as something new, it can deteriorate if necessary.

The Bottom Line About Spray Foam Insulation Issues

Spray foam insulation is not a miracle product, nor is it foolproof. A qualified contractor should install spray foam to achieve an effective result. Spray foam installed with a DIY kit has higher risks for these problems.

If you choose spray foam insulation, you are not signing up for mold, termite damage, and air quality issues. However, you must remember that the difference between a problematic spray foam and a worthwhile permanent insulation is the installer's expertise.

We do not want any homeowner to experience the frustrations of failed spray foam insulation. Learn how to evaluate your area's contractors to ensure the best outcome.

Now that you know the truth about spray foam insulation, 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.