Is Spray Foam Insulation Safe? (Important Facts)

As a homeowner, it is well within your rights to be concerned about your safety (and that of your loved ones) when installing home insulation. While spray foam boasts one of the best thermal qualities, are they safe in your home?

When properly installed, spray foam insulation is safe. Yes, there is no denying that spray foam emits toxic gas upon insulation. But this stops once the insulation is properly cured. Depending on the spray foam brand, it takes anywhere from 24-72 hours for the spray foam to fully cure. Unless you have specialized experience, it is strongly recommended on safety grounds to hire a professional insulation contractor for installing spray foam in your home.

Spray foam insulation has one of the best R-values. But what really is it made of? Are there instances where spray foam can harm you? Are there locations where you should never use spray foam insulation?

These and many more exciting questions we addressed in this guide.

What is Spray Foam Insulation Made of?

Fundamentally, spray foam insulation is made from two chemical products: polyol and isocyanate. Mixing these chemicals trigger an interesting reaction where the solution expands several times its liquid volume upon spraying.

Depending on the chemical proportion of the mixture, the solution can expand up to 60 times its liquid volume.

This expansion comes in handy, especially in packaging, producing air-tight insulation with a remarkable R-value.

Is Spray Foam Insulation Hazardous to Your health?

The answer to this is: it depends. Let us explain.

Basically, the U.S. Environmental Protection Agency illuminates the danger of spray foam insulation as possibly causing (upon dangerous exposure) eye irritation, sore throat, and shortness of breath.

But this is because of the chemical composition of spray foam. As we said, spray foam has two major components.

These are polyol and isocyanates. Commonly, the polyol portion is enhanced with flame retardants and amine catalysts.

Directly inhaling these chemicals can significantly irritate your lungs. Also, when you directly interact with flame retardants without protection, there is a risk of cancer.

On the other hand, isocyanates can trigger asthma upon being sustainably exposed to them.

But does this make spray foam dangerous and a must-avoid?

No. If you don’t carelessly expose yourself to spray foam insulation, it poses literally zero risk to you.

Improperly mixing spray foam insulation – such that the polyol and isocyanates are mixed in incorrect ratios – is one of the most familiar ways spray foam can harm you.

In such cases of an improper mixture, the spray foam will not stop emitting toxic fumes even after curing some three days after insulation.

Spray foam must be installed by professionals – preferably licensed installers. Upon installation, it is recommended that you vacate the property (or installation site) for some days for the insulation to cure fully.

When properly mixed and fully cured, spray foam insulation becomes 100% safe for your home.

How Long Does Spray Foam Insulation Give off Gas?

As we said, spray foam, when immediately installed, gives off toxic gas. The duration of such emissions depends on the spray foam brand and the installer.

Some spray foam insulation stops giving off gas 24 hours after installation. Some take three days to fully cure and stop emitting gas.

For this time, you should leave your home.

What are the Disadvantages of Spray Foam Insulation?

Regarding thermal capacity, spray foam has one of the highest R-values among all insulation materials. For context, an inch of open-cell spray foam insulation can deliver an R-value of 3.5.

It is even higher in closed-cell spray foam, where the R-value can rise as far as 7 per inch.

This said, spray foam yet has some disadvantages. Let us talk about them.

Very Expensive

Possibly the best things of life are free – except spray foam. Spray foam is one of the most expensive insulation materials you can get.

Just one board foot of spray foam insulation can cost you as much as 65 cents. Also, professional spray foam installers don’t come cheap.

An installer may charge you up to three times what a fiberglass installer would charge. Unfortunately, you can do without a professional installer for spray foam.

A spray foam project can cost you more than $3,700.

Can be Damaged by Water

While spray foam excels in insulating capabilities, it doesn’t do well with moisture. Its water resistance is not the best and can foster the growth of mold and insect invasion.

Tendency to Shrink

This is another disappointing characteristic of spray foam insulation. Spray foam settles over time.

This is because of the expansive characteristics of spray foam – a feature inherent to its insulation strength.

Spray foam insulation could shrink when exposed for a long time to temperature fluctuations. This makes such spray foam insulation less energy efficient.

Where Should You Not Use Spray Foam Insulation?

Spray foam is not suitable for every location. There are areas where installing spray foam insulation can be dangerous and others where the insulation will lose much of its efficiency.

Don’t Install Spray Foam Close to Electrical Boxes

Sometimes you would need to insulate the area separating the exterior wall from the back of your electrical box.

We don’t recommend spray foam for such insulation projects.

This is because such proximity can lead to spray foam penetrating the electrical box and clogging up the components.

More than such expansion, the flammability of such spray foam components can be dangerous when directly exposed to the box.

If, for whatever reason, you insist on installing spray foam very close to electrical boxes, it is best to use a type that doesn’t expand much.

Don’t Install Spray Foam in Closed-Cavity Locations

Suppose you have closed-cavity spots to insulate, don’t spray foam. It is preferable to use injection foam for such spaces as brick exteriors.

The rapid expansion of spray foam may ramp up pressure in such locations.

While spray foam and injection foam share similar expansiveness, injection foam is less pressurizing due to slower expansion.

Don’t Install Open-cell Spray Foam Insulation Directly on Roofs

This prohibition is relatively limited to open-cell spray foam. Open-cell spray foam – from its very nature – is not friends with moisture.

Therefore, when directly installed on roofs, you expose it to significant moisture content. When such moisture coalesces, it will facilitate the rotting of your roof.

If you must use spray foam on roofs, use the closed-cell variant.

Will Mice Eat Through Spray Foam Insulation?

It depends on the conditions. First, spray foam has no edible material rodents can feed on. Therefore, mice would be naturally disinterested in borrowing through them. However, if the mouse is intensely desperate to penetrate your home via the spray foam (say in your attic), it can patiently chew through. That said, this is extremely rare and unlikely.