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.
Douse the insulation in a bleach solution (1 cup bleach and 1 gallon hot water) and scrape clean with a wire brush.
The simple answer is yes, you could technically spray foam insulation over mold.
The Effects of Using Bleach on Porous Surfaces
By now you should have a pretty good idea that you shouldn't use bleach to attempt to kill mold on a porous surface like wood, drywall, insulation, fabric or cardboard.
It's Packed With Embodied Carbon. Chris Magwood has calculated that insulating a home with spray foam puts more CO2 into the atmosphere than it saves over the life of the home.
Between spray foam and blown-in cellulose, which is better? Both spray foam and blown-in cellulose insulation have their advantages. Spray foam has a higher R-value, so it's the more effective insulator.
If you see the benefit of insulating your new construction home correctly from the start for long-term comfort, energy savings month after month, and fewer headaches while you live in the house, then spray foam insulation may very well be worth the extra cost to you.
Technically, mold does not typically grow on the insulation itself. Fiberglass is not a viable food source for mold. Yet mold growth is often found on the top surface of attic insulation.
Whether your spray foam insulation is waterproof depends on the type of material you use. In short, closed cell spray foam is waterproof while open cell spray foam is not. This is because closed cell spray foam insulation is a denser material, while open cell spray foam is lighter and expands more.
Spray foam insulation minimizes moisture-related problems caused by random air leakage because it fills all the cracks and crevices where air enters. Spray foam insulation can effectively seal roofs and other spaces where condensation is more likely.
Mold is a serious problem that can lead to respiratory issues and other illnesses, so moldy insulation should be removed immediately. Take care when removing the insulation to isolate the spores and dispose of the moldy products properly.
You are more likely to find mold on the top surface of attic insulation sheets, and you might see the spores or growth on settled dust. This growth can happen with leaky roofs and looks like a black or thin, spotty gray layer spread out in different patterns.
Fiberglass, a non-biodegradable substance is resistant to mold. With its sharp, ground glass, mold spores puncture before they can attach to it. Mold can grow on the fiberglass insulation backing, which is made of paper and is a mold food source. Fiberglass insulation without backing may be the best choice.
Most of the time, the only area of the home that has to be treated is the attic and nowhere else. Mold in attics is very common and can usually be dealt with quickly and effectively. No need to panic and treat your home as if it's uninhabitable and beyond repair. Attic mold is caused by moisture and mildew issues.
In most cases, attic sheathing with mold does not have to be removed unless there is significant structural damage. However, it does need to be carefully treated and sealed.
For a natural solution for getting rid of black mold, combine one part baking soda with five parts distilled white vinegar and five parts water in a spray bottle. Alternatively, you can use a chemical-based mold and mildew remover, all-purpose cleaners, bleach or dish soap.
Black Spots on Insulation caused by Air Leakage
Particulates released by combustion appliances, such as wood stoves, boilers, furnaces, diesel heaters or auto exhaust, can produce very fine soot that can build up over time in insulation. Tobacco smoke can also contribute.
Although insulation helps to reduce moisture, it can also trap it, particularly in basements, leading to mold growth between insulation and walls.
Insulation turns black when it comes into contact with airflow, causing dirt or dust to collect on the insulation and make it turn black. Or, if there's moisture and airflow, black mold can grow on and possibly eat away at your insulation. To solve your black insulation problem, you can clean or replace the insulation.
So why is it a problem for mortgage lenders? By sealing the roof space with this material, air circulation can be restricted to the roof and timbers. This can lead to condensation, which in turn can eventually lead to the rotting of the wooden roof supports.
Spray foam really is a magical tool for household insulation. Although fiberglass has been commonly used for insulation, spray foam can actually outperform it. Plus, with so many ways you can use spray foam, this material certainly is handy.
Typical Insulation Lifespan
The International Association of Certified Home Inspectors states that spray foam insulation, wrap tape and housewrap insulation can last for more than 80 years. At the same time, cellulose, loose-fill, foamboard, loose fill and rock wool insulation can last up to 100 years.