Does spray foam crack over time?

Author: Prof. Francis Welch I  |  Last update: Saturday, November 1, 2025

The curing process after spray foam is applied inherently entails shrinkage and hardening. Not only can such shrinkage result in pulling back from stud bays and other connections - which often leads to gaps in the insulation layer - it can lead to cracking within the foam structure itself.

What causes spray foam to crack?

There are a couple of reasons for this type of failure. The most common are thermal shock in the winter, poor installation technique, or overheating of the foam during installation on a hot day.

Does spray foam break down over time?

In general, spray foam doesn't deteriorate because of its inert nature, preventing it from reacting with other substances and reducing the risk of chemical breakdown or disintegration.

What is the lifespan of spray foam?

Both types of spray foam insulation can last anywhere from 80 years to 100 years, with closed cell spray foam having a slight edge in terms of durability. For most families, this represents the lifetime of the house and then some!

How to tell if spray foam is bad?

If you're noticing that your spray foam is still soft even after a day, you probably have bad spray foam in your building. You can also determine whether the spray foam has been cured or not by using a knife. If you're able to cut through the spray foam with one quick motion, then it's still uncured.

Does Spray Foam Insulation Crack? | Spraying too thick too quick

Can mold grow behind spray foam insulation?

Mold and mildew can begin growing behind the insulation which can go unnoticed until it's already become a huge problem. This often happens when the spray foam isn't installed correctly and space is left between the insulation and the wall, which allows moisture in and gives mold the perfect place to grow, unfettered.

Does expanding foam go bad?

Over time, the catalyst become less active until it eventually loses its ability to catalyze the reaction. As a result, you can get a poor application including foam shrinkage.

Why we don t use spray foam?

Homeowners who are exposed to isocyanates and other spray foam chemicals in vapors, aerosols, and dust during or after the installation process "run the risk of developing asthma, sensitization, lung damage, other respiratory and breathing problems, and skin and eye irritation.

Does foam deteriorate over time?

As an inert product, spray foam does not break down. However, over time, all types of insulation experience decreased R-value, the unit of measurement that indicates how well insulation restricts conductive heat flow.

Can you spray foam over old spray foam?

If you do choose to insulate existing walls, it's once again best practice to start fresh, pulling out the old insulation and applying fresh spray foam.

Is there a downside to spray foam insulation?

Spray foam insulation is a good insulator in terms of keeping a room warm or cool. But its many downsides outweigh the benefits. These include, making it more difficult getting a mortgage, potential health issues, environmental damage, ventilation issues and a lower home valuation.

How much does it cost to spray foam for 1500 square feet?

The cost to insulate an attic is usually between $1.50 and $3.50 per square foot. This price can change depending on the attic's size and how easy it is to get to. For a typical 1,500-square-foot attic, you pay $2,250 to $5,250.

Where should you not use spray foam?

Directly against electrical wiring or fixtures: Spray foam insulation should not be applied directly against electrical wiring, fixtures, or recessed lighting unless they are rated for contact with insulation. Contact with insulation can cause overheating and pose a fire hazard.

How do you fix cracked foam?

You can use any kind of spray glue to repair your broken styrofoam piece. If you'd like to use exactly what Tim uses, use "Great Stuff" brand insulating foam sealant 'for Gaps and Cracks. ' ("Great Stuff" is Tim's preference for gluing together broken styrofoam pieces.

Can water leak through spray foam?

Spray foam insulation repels water; when applied to your home, it creates a barrier that stops water from entering your house. This is particularly beneficial for areas that are prone to flooding or heavy rainfall.

What is the lifespan of foam?

The lifespan of EPS is long, potentially unlimited. Most of the testing has involved placing EPS foam in a reactive environment such as soil where it performs extremely well. It is expected, especially in above ground applications that are sealed from pollutants and other forces that lifespan is indefinite.

What happens to foam when it gets wet?

Open-cell spray foam is more porous than closed-cell foam, so it may absorb water if it gets wet. This can lead to decreased R-value and, over time, the potential development of mold or mildew if the moisture is not properly addressed.

Is spray foam a bad investment?

Spray foam insulation is expensive but can be an excellent investment for residential and commercial properties.

What is the best alternative to spray foam insulation?

Instead of spray foam, Curtis recommends cotton denim insulation, which is typically made from industrial scraps.

Can you sleep in a house after spray foam insulation?

Spray foam insulation needs time to cure before it's safe to sleep in the home. Good ventilation is key during and after installation to reduce off-gassing and health risks.

What destroys expanding foam?

Yes, WD-40 does remove expanding foam as it can break down the foam residue.

How to keep foam from deteriorating?

Cushion Wrap Silk Film is a noiseless plastic silk film that you can wrap around your foam to protect it from moisture. Silk film is designed to be silent so you will not hear it crinkling when you sit on your cushion assembly.

Does foam degrade over time?

While it resists most chemicals, plastic foam's one weakness is sunlight. In a process called photodegradation, requiring consistent exposure to sunlight, polystyrene does start to break down, eventually forming a powdery substance. Unfortunately, many people mistake this process for decomposition or biodegradation.

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