How to check for mold in basement? If you notice a musty odor permeating throughout your home, there’s a high chance it’s mold. There are several ways to confirm this, which include smelling or inspecting it. Mold can become a health hazard when left alone, and that means identifying mold in the basement should be your priority as soon as you think you have it.
Below, I discussed the best ways to check for mold in your basement and how to remove them.
How to Check for Mold in Basement?
1. Check for a plumbing leak
Moisture is the number one culprit behind mold growth in basements. If you see mold near plumbing fixtures, mold is likely feeding off a leakage. To confirm, let the water run while you check the pipes and their surrounding areas.
Look for damp spots and see if there’s mold from water leaking. Keep in mind that water travels in any direction. That means even if the mold is growing in your basement, the actual leak may be some distance away.
Either way, once you find the leak source, fix it immediately.
2. Look for grimy areas throughout the basement
Inspect your basement thoroughly. Check its floors, walls, and baseboards for grimy patches. These appear slimy and are often colored black, green, or white with orange hues.
Also, when inspecting for grimy areas, look for stains with a yellowish tint. That’s because this is a sign of mold growth. Under ideal conditions, it can take between 1 to 2 days for mold to germinate and spread.
Its spores start to colonize within 3 to 12 days and become visible in surfaces around 18 to 21 days.
3. Probe the moldy area with a screwdriver
Mildew originates from mold, and it’s a surface type of mold that won’t damage your home’s structure. However, other types of mold can lead to rapid decay.
To differentiate mold from mildew, probe the suspect area with a screwdriver. You can also use other sharp tools to test the mold. If the wood feels soft or begins to crumble, you have a moldy surface, and it has taken hold of the material.
When this happens, it means the structure of that particular area has begun to rot.
4. Check for mold and leakage outside
If you notice excess mold growing on an exterior wall in your basement or ceiling, look for a leak. Leaks are common on walls and roofs, and these are the best sources for mold testing.
Measure from the moldy surface to a reference point. After choosing a reference point, look for the spot on the opposite side of the walls or ceiling.
Inspect nearby ventilation systems, decks, windows, or any area where wood is rotting. Also, look for any ground sloping toward your house and downspouts emptying next to the walls.
If the grounds surrounding your home become too wet, this can lead to mold growth. Moisture will wick into the structure of your home and become persistent dampness.
5. Visually locate mold growth
Mold grows everywhere, and it especially thrives in damp environments like the basement. One of the easiest ways to check for mold growth is through visual inspection.
This fungus can grow nearly anywhere its spores land, find moisture, and have a warm ambiance. You can spot the most visible type of mold, called mildew, and they start as small black spots, which grow into larger colonies.
These are the grimy black stuff you see that grows on damp walls or painted sidings.
6. Thoroughly inspect the basement’s ductwork
If you don’t have any roof leakage but have mold growing on your ceilings, your ductwork might be the issue. Poorly insulated ductwork can lead to mold formation, especially under ducts or registers.
Warm and moist air condenses inside the ducts, forming water. These then carry cold air through the attic and crawl space, leading to condensation. It’s a sign that your ducts may be uninsulated or have a missing vapor barrier.
Nevertheless, the water inside these ducts will saturate the insulation and drywall. And this is where mold spores take root. From here, mold will continue to spread, even if your ducts have a reliable filter in place.
7. Identify areas known to harbor mold
Knowing the most susceptible areas for mold growth is a great way to check your basement fast. Although it differs for each household, here are the most common places to look for mold in the basement:
- Around water supply pipes or drainage lines
- Anywhere near a dryer vent
- The ceilings above finished basements
- Near bathroom exhausts
- Inside walls
- Around sump pumps
8. Smell the basement for mold
If you’ve been noticing constant and strange smells in your basement, it may be a sign of mold growth. Mold has a unique odor, consisting of a strong, musty, damp, earthy, and tangy smell.
The mold smell originates from the microbial volatile organic compounds it releases. The bigger this fungus gets, the stronger it smells. You can tell the smell is coming from mold as its odor is overpowering. And it’s especially potent when confined to one area.
Moreover, if you or your family have asthma or allergies, mold can trigger your conditions. That’s because mold is a common allergen, and its smell can trigger allergic reactions.
If you’ve been dealing with allergies at home, you may have a mold problem.
What To Do If You Have Mold In Your Basement
If you need to remove mold in your basement, we recommend that you take extra precautions. You want to not only avoid contaminating your home but also protect yourself.
Breathing high concentrations of spores and volatile organic compounds can be dangerous. To keep yourself safe and protected when dealing with mold, keep the following points in mind:
What To Do:
- Wear old clothing or shoes you can launder or throw after cleaning.
- Wear N-95 or P-100 respirator masks, goggles, and gloves.
- Set an electric fan or air purifier with a clean HEPA filter to ventilate and clean the surrounding air while removing the mold.
- Wrap any mold-infested items with a 6-mil plastic and double-bag and throw them away immediately.
- Moisten moldy areas with a garden sprayer to control airborne spores.
- Turn off your HVAC system and cover ductwork and doors to prevent spores from spreading.
What Not To Do:
- Do not handle mold directly.
- Avoid working in an enclosed area without ventilation.
- Never directly inhale mold.
- Avoid using a wet vacuum cleaner as it can absorb spores.
How to Remove Mold in the Basement
Knowing how to check for mold in the basement is one thing, but removing it is just as important. To safely remove mold in your basement, follow these steps:
Step 1: Prepare the work area
Ventilate your work area with a box fan, and make sure the airflow is moving toward the exterior to prevent spores from spreading. Also, tape plastic around the area as spores tend to fall on the ground as well.
Step 2: Ensure the work area is completely dry.
Using a wet or dry vacuum, make sure to clean up any water throughout your basement. Meanwhile, to deal with other latent moisture, increase the heat inside the room.
You can also turn on your dehumidifiers and leave the fan running until the basement is entirely dry.
Step 3: Wash the mold with soap and water
Once the entire moldy area is dry, wash the mold with soap and water. This combination has surfactants that can help remove the mold efficiently and safely.
Step 4: Spray the mold with mold remover
After rinsing the mold with soap and water, spray it down with a mold remover. Wipe it across the surface with a sponge to ensure it gets into the deepest parts. Once finished, let the mold remover solution dry.
Step 5: Clean the dried mold
When the mold remover dries, the mold spores die alongside it. However, the mold will remain visible. You can choose to paint over the mold with latex paint or clean the area with hot water and dish detergent.
Step 6: Use an antimicrobial spray on the mold
Spray an antimicrobial solution to the affected area before doing your finishing touches. Don’t forget this step, whether you’re painting over or cleaning it with a detergent and hot water.
Spraying an antimicrobial treatment spray on the mold prevents the fungus from returning. However, in larger basements, it’s more efficient to fog the whole room.
Frequently Asked Questions
Q: How Common Is Having Mold In The Basement?
A: Since basements are at the bottom of the house, it’s naturally dark and damp. Plus, water damage in basements comes hand in hand with mold formation. For these reasons, mold growth has become common in basements.
Q: Is Having Mold In My Basement Dangerous?
A: Having toxic mold in the basement can be dangerous to your family’s health. Excess growth of toxic mold can irritate the eyes and respiratory system, and it also can cause pungent odors in your basement. Mold is especially hazardous for those with allergies or generally weak immune systems.
Q: Can I Still Live In My House Even If I Have A Moldy Basement?
A: You can still live in your home with a moldy basement, but expect some health issues along the way. That’s because any mold inside a home can lead to severe health problems. If you’re dealing with a mold-infested basement, address it right away.
Q: Does Having Mold In My Basement Affect My Health?
A: Prolonged black mold exposure can lead to sickness affecting your respiratory system, and these include asthma, nose, and throat issues. But the effects of mold on your health can go beyond this and may lead to physical concerns like headaches.
Q: Can I Do A DIY Test On Black Mold?
A: To go the DIY route when testing for mold, you’ll need to buy a mold testing kit. With this, you need to take samples of the air and affected areas in your basement independently. Then, you’ll need to send the samples to a testing facility, which will report what type of mold you have.
Final Words
How to check for mold in basement? There are many ways to test for mold in your basement, but one thing is for sure: you need to address it immediately. After all, mold isn’t only unsightly, and it’s also hazardous for your health. Checking and removing mold can be tricky, but it is possible!

Home Air Quality is founded by Bernard K to provide information on Indoor Air Quality in Homes and enlighten people about what they need to know about creating and maintaining a comfortable and healthy home environment.
We believe that “Quality air brings a healthy life.”