You’ve got mold in your attic caused by poor insulation and moisture issues.

Now you know it’s time to nip it in the bud and update your insulation and you know you want spray foam, but does that mold need to be removed first?

Having had the pleasure of working in the construction industry for more than 35 years, along the way, I’ve managed to expand my education in certain specialized areas of construction. 

One certificate I hold is being a certified mold inspector/remediator with NAMP (National Association of Mold Professionals). This area of expertise is the one I use on a regular basis during appointments with homeowners as a project manager here at RetroFoam of Michigan. 

The most commonly asked question I receive is, “Do I have to remove mold from my attic before installing spray foam?” 

Before I answer this question, let’s look a little closer at what mold is and why it happens.

How to Identify Black Mold in a Home

There are over 100,000 different types of mold, and many are just a nuisance for those that suffer from allergies or asthma. 

There are only a handful of molds that are considered dangerous to everyday people, Stachybotrys, Aspergillus, and Cladosporium to name just a few. 

These molds are dangerous when inhaled and affect young children, the elderly, and people with suppressed immune systems. 

It’s impossible to tell if you have a dangerous mold just by looking at it, even if it is black in color, not all black molds are dangerous. The only way to tell what type of mold is growing in your attic, basement, or crawl space and if it’s dangerous, is by doing a tape test and having an accredited laboratory grow the mold and study it under a microscope. 

Most big DIY stores sell mold testing kits that contain a tape lift, chain of custody, and prepaid envelope with the laboratory’s address included.

Does Mold Remediation Need to Be Done First and Does Spray Foam Encapsulate Mold?

So, back to the original question, “Do I need to remove mold from my attic before installing spray foam?” 

The short answer is no but spraying foam insulation over mold isn’t a magic cure. 

Will spray foam kill mold? Yes, because spray foam creates an air seal and will starve that mold of its food source -- moisture and oxygen -- and will inhibit any future growth, it will also cause the mold to become dormant. 

There is the bigger question though of why does that mold grow in attics?

Attics are a perfect breeding ground for mold, especially those attics with insufficient insulation and inadequate ventilation. 

Moisture build-up is common in cooler climates. Up to 40 percent of all heat loss in a house is lost through the roof. When the heat rises into the attic it creates a temperature difference from the outside air. With this temperature difference, condensation forms on the roof deck and this is a molds food source.

It’s extremely important that homeowners check their attics on a regular basis, to make sure their insulation is still working for them and their ventilation is still removing that warm air. 

Another issue you see on a regular basis, are bathroom extraction fans, where the duct over time has become disconnected and is no longer removing that warm humid air to the outside. Now it’s venting straight into the attic. 

Leaving those attics unchecked could cost you thousands in the long run.

Mold remediation is a costly process ranging from $5,000 to $10,000, depending on the severity of the mold infestation. 

Why is it so expensive? 

Remediators will use specially formulated cleaning solutions, abrasive sanding, and encapsulating paints. Attic roof decks are the most difficult area of the house to do remediation. 

I’m sure everyone has looked at an attic roof deck before and seen hundreds and hundreds of protruding nails from where felt and shingles have been installed on the roof. Sometimes it’s multiple layers of shingles, so imagine having to sand mold from that plywood. It is very labor-intensive work. Some remediation companies even use dry-ice blasting to remove the mold because of the difficulties associated with attic roof decks.

Every good remediation company will also tell you, even after your remediation is complete, there are no guarantees mold won’t return.

Why is that? This goes back to why the mold grew in the first place, insufficient insulation, inadequate ventilation, or a compromised roof system. It’s important to know if mold was caused due to a compromised roof system and if that failure is causing roof leaks. If so, fixing all and any roof leaks is an absolute must before making any other decisions.

If mold is due to insufficient insulation or inadequate ventilation, deciding to spray foam insulation in an attic, especially on a roof deck, solves both of these problems. 

Spraying the roof deck creates a conditioned attic space where ventilation is no longer needed. Condensation can no longer form on the roof deck as the foam insulation has created that barrier that doesn’t allow the cold air to meet the warm air, no condensation, no need for ventilation.

Creating a Healthier Home

Having a comfortable and energy-efficient home are both bonuses, but a healthy home is even more important.

Stopping mold in its tracks is the priority, but think for just a moment – if your old insulation allowed for mold to form, what other allergens did it also allow in.

Foam insulation throughout your home can combat the mold issues we’ve already discussed, but it can also reduce other airborne allergens and pollutants from getting inside your house. This is all possible because of that air seal that will also create a more comfortable and energy-efficient home.

The foam insulation products we install in homes have a lot of great benefits for you and your home. If you’d like to learn more, check out the Learning Center on our website. You’ll find a lot of great resources there to answer all of your questions about home insulation. 

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