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Can You Spray Foam Insulation Over Mold?

mold | spray foam insulation

Can You Spray Foam Insulation Over Mold? Blog Feature
Eric Garcia

By: Eric Garcia on February 26th, 2020

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You have a mold problem and are curious if spray foam insulation can be sprayed over mold?

I know what you are thinking. I’m thinking maybe you have mold in the crawl space and the crawl space also needs new insulation, so why not tackle them both with spray foam and be done with it?

Even though I highly admire your ambitious thinking to get stuff done, I don’t fully agree with this convenient option to solve your mold problem in the long-term.

Having insulated over 14,000 projects with foam insulation since 2001, we’ve talked with plenty of homeowners looking to use foam insulation to kill two birds with one stone. From our vast experience, I’ll give my take on the question if you can and should spray foam insulation over mold.

Spray Foam Insulation Over Mold?

The simple answer is yes, you could technically spray foam insulation over mold. However, just because you can do something doesn’t necessarily mean you should.

The thing is if you spray foam insulation over mold it doesn't solve the mold problem. Now, most premium spray foam insulation on the market will not sustain mold growth - there's no food source in the actual foam for the mold to grow on. So, it can help to stunt the growth and keep it from spreading but it doesn't necessarily solve your problem.

I always recommend to anyone who has mold present to first take care of the mold problem before applying foam insulation. Whether you are experiencing mold in your crawl space, basement, or attic, it is best to first address the mold issue before spray foam is applied in the area.

Solve for the Root Cause of Mold in Your Home

Mold can potentially lead to a dangerous health situation for your family members so it is something not to take lightly. 

Since it is caused by excess moisture, finding and fixing the source of the mold, as well as cleaning it up properly, is a critical first step to ensure it doesn’t come back. This could mean fixing leaky pipes or foundation walls before adding foam insulation to the area.

Hazards of Spray Foam Insulation Over Mold

If you do decide to spray foam over the top of mold it definitely can stunt the growth and contain it, but could very well cause problems down the road. 

Spray foam is designed to stay in place with the building for years and years to come, and now the mold can still be causing problems in that area. 

Now, how does that relate to spray foam? 

Well, if the wall or roof deck or basement or any type of structure is damaged over the years, that can potentially cause issues with the foam because now whatever it's applied to could shift, settle, or break apart from the rest of the home. Again, that's kind of worst-case scenario, but keep in mind it can happen.

To summarize, if you have mold going on take care of it before you put spray foam over top of it. I’d rather be safe and fix the root cause of the problem than take the easy route that may cause more damage or challenges down the road.

Suggested Reading

8 Things to Do When Identifying Condensation or Mold in Your Home

When is it Time to Replace the Insulation in My Existing Home?


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About Eric Garcia

Eric brings his knowledge and training in building science, training in spray and injection foams from the manufacturers, more than 8 years installing foam insulation, as well as selling and managing in the foam insulation industry. He is also BPI and Dale Carnegie certified and has taken several building science courses including air sealing and building envelope. Eric’s responsibilities include overseeing and giving support to all of the branches of the RetroFoam of Michigan company, office, estimates, and installs. He is also the Professor of Foam on our educational YouTube series Foam University. Even when Eric is off he is usually still “working” or thinking about work, but when he can get away he enjoys camping, hiking, hunting, and woodwork.