Improperly installed insulation can have a negative effect on a home with regards to mold growth. For example, gaps left in the insulation can create cold spots that can lead to condensation and surface mold growth.
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. Cellulose insulation is constructed of ground paper, which is an ideal food source for the growth of mold if it becomes wet.
Although insulation helps to reduce moisture, it can also trap it, particularly in basements, leading to mold growth between insulation and walls.
Insulation's ability to help manage temperature and moisture makes it one of the most powerful preventative tools against indoor mold growth. Correctly installed, it supports dry, temperature-controlled conditions that inhibit mold growth.
When portions of insulating material harbor mold spores, then you should replace it. Even if the material dries out, mold spores can become airborne and travel to other wet areas of the house. If you catch it early enough, then you'll only need to replace a small section of material, keeping your cost lower.
How long does it take for mold to grow on wet insulation? Mold begins growing between 24-48 hours after your insulation gets wet.
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.
You might think that you will need to replace wet insulation. While it does lose its potency when wet, it can regain effectiveness as it dries up. You should look out for any loose insulation that is wet with dirty water. Wet insulation will join its fibers together and create clumps in your attic.
Unless you have paper backed, or wool insulation, mould does not decompose fiberglass insulation. Most often mould is found on the dust in the insulation, sometimes like the picture above the dark areas are dust caused by thermal bridging (air infiltration) and not mold.
Douse the insulation in a bleach solution (1 cup bleach and 1 gallon hot water) and scrape clean with a wire brush.
If you notice any discoloration on your insulation such as brown, black, or even pink or orange particles, you are dealing with a dirt or mold problem. Insulation sheets are a solid color, so any discoloration will be obvious.
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.
Mould appears on ceilings due to dampness caused by roof damage and leak, high humidity levels, bad ventilation, cooking, condensation, etc. Once it appears, mould will spread fast, actually way faster than it would outdoors.
There are a few ways that insulation in the home can have an adverse health effect. Insulation can make you ill in a variety of ways, often presenting some allergies or the flu. Improper Installation--This could be poorly installed or hung insulation, or simply using the wrong material in the wrong space.
Wet insulation in a wall will migrate to the bottom soaking the wallboard and framing materials. Wetness (existing even just for a few days) will not only reduce the insulating quality of the insulation, but it might not dry soon enough to prevent mold and wood decay from forming.
Even if you must remove most or all of the insulation, it's sometimes possible to dry out and replace the same fibers—that is, after you thoroughly clean and dry the mold-damaged space.
Stachybotrys chartarum typically appears black or extremely dark gray in color. This mold tends to have very round splotches with a speckled appearance. Often, you see darker layers of mold over lighter layers.
When you look for mold on your insulation, you'll notice a thin grey or black layer on the top of the insulation. Mold growth can be harmful to your health. If there is significant mold growth on your attic insulation, removal and replacement is recommended.
According to BobVila.com, mold generally looks slimy or fuzzy, tends to have a raised texture, and can come in a rainbow of colors, including deep green and black. Mildew is powdery, looks white or gray, always appears flat, and grows on surfaces.
How Fast Does Mold Grow? Generally, mold can grow significantly within 24 to 48 hours after water damage. Mold can take hold of your home and grow rapidly within 12 days if it has the ideal conditions it needs to thrive.
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.
Fiberglass insulation, a man-made mineral fiber constructed from a variety of materials, such as sand and recycled glass, is the most popular form of insulation in the United States -- more than 90 percent of homes in America are lined with the pink stuff [source: Spencer and Gulick].