How do you know if there is mold behind drywall?
Elijah King
Updated on February 24, 2026
Be aware of signs that drywalls are moist such as:
- water stains.
- dark rings.
- discoloration.
- deterioration like peeling, bubbling or cracking of the paint or wallpaper.
Is there a way to detect mold behind walls?
Most mold is unmistakable, but sometimes small or largely hidden growths just make a surface look dirty. A quick test for mold can be done when you dip a swab in diluted bleach (1 part bleach, 16 parts water) and dab it on the wall. If the spot quickly lightens (or keeps coming back after cleaning), assume it's mold.How do I get rid of mold behind drywall?
Scrub the surface mold stains from walls and wood trim with a mixture of one quart water and 1/2-cup bleach mold cleaner to kill the mold. Use a soft brush and work until signs of the mold disappear. After scrubbing the surfaces, allow the bleach solution to continue to penetrate the surfaces and dry.Can mold behind drywall affect you?
Doing this is very dangerous because the mold hidden in your walls is as risky or even more risky than the one you can see on the surface. These risks include health implications and structural damage. Mold is risky to your health and loved ones.Can mold behind drywall make you sick?
In some cases, mold in your home can make you sick, especially if you have allergies or asthma. Whether or not you're allergic to molds, mold exposure can irritate your eyes, skin, nose, throat, and lungs.How Can Consumers Detect Mold Inside Their Walls
Should I replace moldy drywall?
Many homeowners attempt to simply repair drywall that is infested with mold, but it should always be fully replaced. If you don't replace every part of your drywall that has experienced mold growth, you're only leaving your home vulnerable to much more damage in the future.How long does it take for mold to spread in walls?
The 48-72 hour window is critical to prevent mold growth as it usually takes 24 to 48 hours for mold to germinate and grow. Once fungus gets a hold on a drywall surface, it can be the breeding ground for thousands of spores and quickly spread in the air around the wall with every passing hour.What does mold smell like in walls?
Musty SmellIf you don't see signs of mold but you can smell it, it may be hidden in your walls. A musty smell is a good indicator that mold is growing in your home. The smell of mold feels earthy, like rotting leaves or decaying wood in a dense, damp forest.
How can I test the air in my house for mold?
If you want to check for mold in your HVAC system, tape the dish to an air duct and blast the air for ten minutes, then cover your dish. The final method is to use a swab to wipe visible mold and then wipe the swab onto the growing medium. This method is best if you can see the mold.What does toxic mold smell like?
Mold has a distinct smell. It's often described as musty and earthy, and may even smell like rotting vegetables or plants. You might notice a musty smell, but not be able to see any mold growing. In this case, you should look for areas that might be exposed to water.What are signs of mold sickness?
If you're sensitive to mold, you may experience the following symptoms:
- sneezing.
- nasal congestion.
- runny nose.
- skin rash.
- itching.
- watery eyes.
- asthma.
- chest tightness.