What does basement mold look like? How to tell when you have a basement mold problem.

A woman with yellow rubber gloves trying to clean mold from the basement wall.

Many people do not know when they have a basement mold problem, or if it’s just harmless cosmetic stains. If you’ve never seen mold, how do you know what mold looks like? There are a few signs you can look for to identify whether you have basement mold. We’ll help you figure out what it means for you!

Where do you find mold?

Ceiling mold damage

Mold is found in wet places, and on surfaces that retain moisture instead of drying properly. If you’re looking for mold, you often find it in the basement. It’s the perfect breeding ground, because it is damp, dark, and above 40 degrees Fahrenheit. Basements are also often unventilated, which makes it easier for humidity to stay in, and basement mold to grow.

When checking for mold around your home, don’t only check your basement. You’ll also want to look:

  1. In bathrooms
      • Shower heads, caulking/grout around tiles and tubs, base of a toilet. All are consistently wet, can cause condensation, and may not always dry fully.
  2. Under kitchen sink and behind refrigerator
      • Both include water pipes that can leak into dark, contained, difficult to access spaces
  3. Around window sills
      • Water may leak through or come in through an open window
  4. Around a washer/dryer, or on the ceiling in the laundry room
      • The heat and moisture combination from the washer and dryer makes it a breeding ground for mold and mildew
  5. Water pipe entry points, or along the pipes
      • If there is an unnoticed leak, moisture can build up and result in mold.
        • If they are uninsulated, they are likely to create condensation, which also can result in moisture and mold.
  6. Areas that have been previously affected by water damage or had leaks
      • Carpeting, drywall, and wallpaper are especially problematic, and can hold in dampness
        • Even if the water isn’t leaking now, the mold can grow from past damage if not allowed to dry fully

What does harmful mold look like?

You’ve probably heard of black mold, and if you haven’t, we’ll tell you – it’s not pleasant, and it’s not healthy. Black mold is toxic and grows in damp, warm environments like your basement.

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mold on walls
mold on walls

It will often be slimy, and a dark color that shifts from green to black or even gray.

If you see something you think may be black mold, call a professional immediately. Your family will thank you!

Not all mold is toxic. For example, the type of mold you see on your food might not hurt you, but it doesn’t mean you want to eat it, and you certainly don’t want it in your home or basement.

Some mold is: Furry growths, like on food. Typically, mold colonies will grow in round patterns.

Moldy sponge

They come in many different colors, other than just black; mold can also be green, white, brown, or yellow.

A good identifier of basement mold or mold in your home is a yellow or pink stain on wallpaper or drywall or wood. That often means there is mold growing in that area.

What does basement mold smell like?

Musty, mildew, and dirty. That’s the simplest way to put it. If you walk into your basement and are hit with an unclean, earthy scent, you likely have some type of mold in the basement. Again, it may not be toxic, but make sure you’re checking at-risk areas to find anything that may be dangerous.


Mold damage

What do I do if I think I have mold?

A simple, inexpensive fix is increasing the light in the space. You’ll want to look for LED bulbs above 4,000K in spectrum temperature, or 100-watt bulbs, in a larger area. In smaller areas, a 40-60 watt is acceptable. Leave these lights on continuously in a basement with lots of mold or mildew. This trick will stop mold growth in basements or any other dark, damp space in your home.

The key to keeping your family safe and comfortable is ensuring you are looking for signs of unhealthy and unsightly mold. If you’re not sure, call an expert! They’ll help you determine next steps.

At Basement Waterproofing, we’ll come by for a free, no-obligation estimate, give you all your options, and let you make the decision that is right for you. Just give us a call at 800-439-4951, and we'll be happy to help.


To help bring you supporting information, we’ve referred to the following sources:


How to Remove Black Mold

Toxic vs. Non-Toxic Mold

Common types of Home Mold

Mold Damage


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