When Insulation Turn Black: Explained

If you’re like most homeowners in the United States or Canada, you’re probably familiar with fiberglass insulation that’s pink or a similar bright shade. This type of insulation is what’s typically used in many buildings throughout the U.S. since it’s affordable and effective when properly installed. But there are times when insulation that was once a bright, vibrant hue turns black or a very dingy shade of gray over time. When this happens, it’s usually a sign you have an air leak.

Understandably, you may have concerns about discolored insulation should you happen to find it. However, it can actually be a good thing in some cases, especially if your goal is to make your home as energy efficient as possible, but more on this later. Now, here’s what you need to know about insulation that turns black or becomes unnaturally discolored and what can be done to deal with this problem.

Why Air Leaks Turn Insulation Black

Fiberglass insulation gets darker when exposed to a steady flow of air over the years. This happens because the air that makes it to insulation usually contains dust, dirt, debris, and other particulates. Air can also carry moisture. All these substances can slowly and steadily turn fiberglass insulation black. Another reason why insulation could become discolored is because of issues with mold, which are sometimes related to air and moisture exposure.

How Air Leaks Happen

Insulation is often out of sight, out of mind. This is part of the reason why air leaks often go undetected until you clearly see discolored insulation or get a whiff of odd odors suggesting your insulation may be moldy. As for why air leaks happen, some of the common culprits include:

  • Electrical wires: When electrical wires are installed, some contractors simply use insulation to cover gaps or holes created for wires. Doing so can create passages for air.
  • Pipes: The same thing can happen if holes created for pipes aren’t sufficiently blocked once everything is in place, even though this is typically required as per local or industry codes.
  • Air duct chase: Air gaps may exist around ducts used to carry either supply air or return air to a home’s HVAC system, or humidity may cause moisture to become an issue.
  • Damaged roof: Damage to the underside of a roof sometimes creates gaps for air and moisture, especially if roof insulation is worn or damaged as well.

How Insulation Becomes Affected by Mold

Mold sometimes grows on fiberglass insulation backing. In some instances, mold may also be found on the dust particles that get in through air gaps and accumulate on insulation. Moisture that accumulates on insulation from air exposure is another way mold could form on insulation. If fiberglass insulation is directly in your hearing and ductwork, it can also develop mold because of exposure to high humidity levels.

Testing for Mold

If you have a partially opened basement wall, one way to detect mold is to simply take the time to do a visual inspection, especially within areas where your insulation is discolored. With testing, you can collect a sample and use a home mold test kit to get results. Another option is to have a professional mold remediation expert do the testing.

One other way to test for mold is to send a bulk sample of the affected section of insulation to a private lab that does mold testing. The sample should be sealed in an airtight plastic bag. Collect about a square foot of insulation and cut entirely through the insulation blanket. This will ensure there is sufficient material to test. Also, include any plastic, foil, or kraft paper backing as well so these materials can be tested, too.

Fixing a Mold Issue

Fixing a mold issue means getting rid of the source of the mold. If it’s air exposure where the insulation is located, fill up any clear holes or gaps. You’ll also want to replace any clearly discolored or damaged insulation with new insulation. If your home is excessively humid, it may be worth considering the installation of a whole house dehumidifier if proper ventilation can’t be created to minimize humidity that may affect your insulation.

How To Fix Air Leaks Affecting Your Insulation

Remember how we mentioned that black insulation can sometimes be a good thing? The reason for saying this is because if it’s found during a routine home inspection or when you are making home improvements or updates, it clearly shows where you likely have issues with an air leak or moisture exposure.

Getting clues from the color of your insulation can take some of the guesswork out of finding the source of the problem. Now, let’s talk about what you can do to fix air leaks affecting your insulation.

Safety Gear You Should Wear

Working with fiberglass insulation that needs to be removed or replaced because of air/moisture damage means you’ll be exposed to fiberglass fibers. Since there are potential risks associated with harmful fiberglass particles, it’s important to use the right safety gear. Typically, the following safety precautions are recommended:

  • Wearing a high-quality respirator
  • Wearing gloves when touching fiberglass insulation to keep from spreading the fibers around
  • Wearing a long-sleeve shirt and long pants so your skin isn’t directly exposed

Additional steps you take will depend on what’s causing the air leak or moisture exposure. If you have a leaking pipe, for instance, a plumber can properly repair the pipe before new insulation is inserted. Quality caulk or canned foam can be used if the only issue is a hole or gap that needs sealed. With roof damage affecting insulation, the approach to repair will depend on what part of the roof is damage and how widespread the issue is.

Lastly, if you have concerns about fixing the problem yourself, call on a professional to ensure new insulation is properly installed and the contributing problem is addressed. Even just having a professional do an inspection once you’re done can provide some added peace of mind and reduce your risk of having future insulation issues.