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.
The PROBLeM wiTh MOLd
Mildew (mold in early stage) and molds grow on wood products, ceiling tiles, cardboard, wallpaper, carpets, drywall, fabric, plants, foods, insulation, decaying leaves and other organic materials. Mold growths, or colonies, can start to grow on a damp surface within 24 to 48 hours.
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.
Moldy and Dirty Insulation
In some cases, the top few inches can be removed and retrofitted, but this might cost more than replacing all of it in the area. Often, the mold or dirt you find and worry about is harmless. In any case, you should not try removing it yourself just in case it is dangerous black mold.
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.
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.
Although insulation helps to reduce moisture, it can also trap it, particularly in basements, leading to mold growth between insulation and walls.
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.
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.
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.
When searching for black mold, look for circular-shaped spots that are black, dark green or dark brown. Some black mold can also take on shades of orange or have flecks of white within it. Most of the time, black mold has a slightly furry appearance.
Unless damaged, it can last 80 to 100 years in most houses before it needs to be replaced. However, insulation can start falling from fiberglass batts after 15 to 20 years, so if your insulation was installed in batts well over a decade ago, it might be time for an inspection or a home energy audit.
Wet insulation can be a health hazard that allows mold and mildew to grow. When you notice any wet insulation in your attic, you need to find the source of the problem and fix it as soon as possible. Wet insulation is a serious problem.
Douse the insulation in a bleach solution (1 cup bleach and 1 gallon hot water) and scrape clean with a wire brush.
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.
Foam building insulation, in both spray foam and foam board products, is resistant to mold growth but as we will explain here it is not absolutely mold-roof, and on occasion we do find mold growth on the surface of even closed-cell foam, in open-celled foam (rare), and on th surface of EPS and other foam insulating ...
To help fiberglass insulation dry out, place a dehumidifier or fan in the area. If possible, remove the affected batts and transfer them to a warm place to dry. Once dry, return the insulation to the wall or floor cavity where it came from.
If you have loose-fill insulation that is gray, soft, and without a shine, it is probably cellulose insulation. Cellulose contains a high percentage of recycled paper and does not contain minerals. In general, it looks like shredded gray paper.
Blown fiberglass comes in three common colors: white, pink or yellow and the colors simply identify the manufacturer. Blown-in fiberglass insulation in attics typically has an R-value of 2.5 per inch. The density of the blown-in fiberglass determines the R-value just like it does for a batt.
Therefore, when looking for and trying to identify asbestos insulation, check the areas that are the most vulnerable to heat transfer. That's where you'll find insulation material, which may contain asbestos. Asbestos insulation is usually found in the less-visible parts of the home, including the following: Attics.
Properly working insulation should be a yellow, white, green or pink color depending on the manufacturer. Move the insulation on the basement ceiling around a little bit (just use a wooden spoon or other object to push it back and forth) to see if it has darkened.