Spray foam is undeniably one of the best insulation materials available for home and commercial buildings. It’s an effective air barrier, helps prevent moisture intrusion, and provides superior insulation compared to other traditional methods.

But, like any product, it’s not perfect. It has quite a few shortcomings, especially concerning its different types and combination with other materials.

But how do you tackle these problems when you run into them? We’ll discuss the problems with their solutions in this guide.

As good as spray foam insulation is, it has its own set of problems. Here are some of them.

1. Misrepresentation of Spray Foam Products

Spray foam insulation has been around for many years and is available under many brand names. However, Icynene-Lapolla seems to be synonymous to spray foam insulation due to its widespread use.

But that’s not to say there are no other brands or quality of foam available. When it comes to choosing the best type of spray foam insulation for their particular project, many people make the mistake of going with the ‘generic’ solution.

It can lead to problems such as poor performance, incorrect application, and expensive repairs down the road.

Solution: It’s essential to do your research and read up on the different types of products before making a purchase decision. Plus, work with an experienced contractor who can help you differentiate between poor-quality spray foam and the real deal.

2. Roof Wood Rot

Besides trapping heat, spray foam insulation can also cause wood rot on your roof.

Spray foam is a great air barrier. But if it’s not applied correctly, it can cause moisture to build up and pool around the edges of the roof, resulting in rot.

Even if you apply the insulation correctly, wood rot can happen. If your roof already had external damage before you applied insulation, rainwater would seep in. Since spray foam creates a barrier, the water cannot evaporate anymore, getting trapped in spray foam insulation.

Over time, the insulation soaks up more water and traps heat too. Heated air will cause evaporation of the water, which is to convert it into vapor. If the insulation produces condensation, it will likely drip and be absorbed by the wood framing, resulting in condensate saturation in the wood trusses and rafters.

Solution: To prevent this from happening, ensure that all exterior surfaces of the roof are in good condition before you apply spray foam insulation. You should also use a breathable membrane for extra protection.

3. Contraction and Pulling Away From Framing

Another common problem with spray foam insulation is its tendency to contract and pull away from the framing. Since it’s an expanding foam, it needs space to expand.

But when you apply it too close to the framing, it can push against the wood and steel studs, which can interfere with its ability to expand. This can cause it to pull away from the framing and create air pockets, reducing its effectiveness as an insulation material.

Solution: The solution to this problem is simple: leaving enough space for the foam to expand. Make sure the foam has enough space away from the framing and the edges of the structure. Remember that different foams have different expansion capabilities. That will give it enough space to expand properly, ensuring it’s doing its job as intended.

4. Foul Smell

Improper application of spray foam insulation can also lead to a foul smell. The chemicals in the spray foam react with moisture and air, producing an unpleasant smell before the foam fully cures. It can be especially problematic in areas with poor ventilation, such as attics and garages.

Suggested read: Help! My Spray Foam Smells! Can I Fix It? (And How)

Solution: When applying spray foam insulation, ensure the area is well-ventilated. You should also use protective gear such as a face mask to protect yourself from these unpleasant odors.

5. Mold and Mildew in Attics

Ideally, spray foam should create a seal that prevents moisture from entering the attic. But if there are any gaps in the insulation, air can escape, and moisture can settle on it.

A common issue with spray foam insulation is non-adhesion, which s usually caused by the foam, the air, or the surface being outside the recommended range. Another common reason is moisture on the surface. As a result, the insulation leaves cavities. These cavities seal water in, facilitating the growth of mildew and mold.

Solution: To solve this problem, you must apply the foam correctly. Ensure that all components are mixed properly and that the foam is applied without leaving any gaps. Moreover, you should also use a moisture barrier to prevent water from entering your attic.

6. Exposure to Isocyanates

One of the biggest dangers of spray foam insulation is exposure to isocyanates. These chemicals are known for their respiratory toxicity and can cause serious health issues.

In mild cases, they result in asthma and may irritate the eyes and skin. Over time, they can lead to lung damage, chronic bronchitis, and other severe respiratory problems.

Solution: Protective gear is essential when using spray foam insulation. Wear safety glasses, gloves, and a respirator mask to protect yourself from these dangerous chemicals.

Additionally, hire a professional to install the insulation, as they have the right tools and experience to do it safely. It will ensure that you and your family are protected from any potential hazards.

7. Flammable

Since it’s a foam plastic, spray foam is flammable. If sparks or open flames come in contact with the insulation, it can quickly catch fire and spread throughout your structure.

Some manufacturers may add fire retardants to the insulation to reduce its flammability, but it’s still not recommended for areas with high heat, unless you’re using fire-resistant expanding foam (like this one) to seal holes between apartments and slow the spread of fire. For example, it’s not suitable for attics and garages located directly below or beside a chimney. Plus, you should never apply spray foam around electrical wires.

Solution: Always follow the manufacturer’s instructions and safety warnings when installing spray foam insulation. Keep open flames away from the insulation and use fire-resistant materials when possible.

Suggested read: What Insulation Offers The Highest Heat Resistance? [With Chart]

8. Hard to Combine With Other Insulation

Spray foam insulation is an excellent solution for hard-to-reach places, such as around joists and between studs. But the downside is that it doesn’t mix well with other insulation materials.

For instance, if you have existing insulation on your walls or attic and want to add spray foam, it can be tricky. You may end up tearing out the old insulation and creating an additional mess.

Solution: The best way to combine different insulation materials is to create a layered system. Install the existing material first, followed by the spray foam. In this way, you can keep the existing insulation intact while adding a layer of spray foam for extra protection.

Suggested read: Can You Spray Foam Over Existing Spray Foam?

It’s safe to say that spray foam insulation has its share of pros and cons. If you’re considering using it for your home, you must consider the potential risks and benefits before deciding.


Justin's been in construction for over 20 years in both new build and renovation. With experience in both commercial and residential construction, he specializes in healthier and more energy-efficient homes.

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