As mentioned,
The black discoloration can be the result of airflow contaminating the insulation with dust and debris. In this situation, it's likely that the insulation wasn't installed properly. There may also be pests nesting in the insulation, bringing in more debris and leaving droppings.
Start by carefully removing the contaminated insulation--avoid disturbing it as much as possible to prevent mold spores from spreading. Dispose of it in sealed bags, and clean surrounding surfaces with a mixture of water and a mold-killing solution like hydrogen peroxide.
What does the mold growth typically look like? Attic mold often appears as a thin grey or black layer on the very top of the insulation. The dimensionality of the growth is difficult to determine, as the underlying insulation presents a rough and uneven surface.
Signs such as discoloration, black or gray spots, and rotting wood indicate mold. Similarly, mold may have a greenish hue with whitish edges as it grows before turning black. If you're using fiberglass insulation, check for sagging or dampened parts of the material.
Mold does not grow directly on insulation because the insulation is not its food source. However, when your attic or crawl space is attacked, then it will spread to the insulation. And as such, it will start to grow on the insulation.
You may face serious repair and replacement costs if you don't deal with blackened insulation promptly. Problems like mold will only get worse over time.
Aureobasidium
This yeast-type fungus can be mistaken for another more sinister and dangerous mold but is far less likely to make you sick. Aureobasidium can start as a slimy pink color, but it will turn brown or black and can look like black mold.
Replace damaged or ineffective insulation: In cases where there is significant water damage or mold growth, it is best to replace the affected insulation.
Humidity problems occur when warm, moisture-laden air interacts with a cool ceiling, causing condensation and subsequent interior mold growth. Liquid moisture problems are due to direct liquid water exposure, i.e. plumbing failures, roof leaks, etc. Occasionally the mold growth is due to a combination of both factors.
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.
Homeowners insurance doesn't usually cover mold damage or removal unless it's the result of a covered peril. If the mold in your residence was caused by something sudden or accidental, such as a bursting pipe or some other covered incident on your policy, you may be protected.
You can get rid of mold by mixing bleach and water. First, mix one gallon of water with one cup of bleach. Then, use a spray bottle to spray the mixture onto the moldy insulation. Let the mixture sit for about 10 minutes, then rinse it with water.
Texture: Asbestos-containing insulation was typically heat-treated, creating an accordion-style texture that gives it a unique look. Color: A lot of asbestos-containing insulation has a gray-brown or silver-gold color. Loose-fill insulation with asbestos tends to have a gray color to it.
Touch 'n Seal Black Gun Foam is a high-performance, single component, moisture curing, Class 1 fire retardant, expanding polyurethane sealant. Black Foam contains UV inhibitors which eliminate the need for painting and is designed to blend in with landscaping, RV, automotive, HVAC and other similar applications.
Mold on your ceiling will usually look like black or green spots but can also be white, pink, blue, or brown. They may have a fuzzy or powdery look and texture and are often slimy.
Although the name implies a uniform coloring, black mold may appear black, dark green, or dark brown. It typically grows as a cluster of round spots with a distinctly wet, slimy appearance. As stated, black mold typically appears fuzzy or furry.
Mildew isn't as pungent in scent, and it looks more fluffy or powdery (but black mold, when cut off from its source of moisture, can take on a mildewy texture). House mildew is often also lighter in color, which is why you'll hear people talk about white mold vs. black mold in terms of good and bad.
One of the most common ways for insulation in your attic or crawl space to turn black is through air leaks. Air flowing into your attic through leaks will carry dust that gets deposited on the insulation. Over time, a sufficiently thick layer of dust will turn your insulation a darker shade.
One of the most visible signs of dirty insulation is discoloration. In addition, the insulation is dirty when it changes color to black, brown, or pink. So, the moment you see black mold on your insulation, you know it is dirty.
In general, the color of insulation doesn't equal better performance over another color. Whether it's pink, white, brown, or yellow—color doesn't influence dependability, reliability, or the products effectiveness.
Insulation, depending on the material used, can last for decades if properly cared for. Some insulation materials are composed of natural materials and will eventually degrade. Others are made from synthetic material and can last for nearly a century before needing replacement.
Check Behind the Baseboards
Put the wood between the wall and the pry bar to avoid any drywall damage. Then you can easily pry the trim away to get access to the bottom of the wall. If there is existing insulation like fiberglass or cellulose, you will be able to see it in the gap at the bottom of the drywall.