Signs of mold in a house
Mold usually announces itself before you see it. These are the signs we see most in South Louisiana homes:
- A musty smell, especially when the AC kicks on or in a closed room. Musty smell, nothing to see
- Spots that come back after you wipe them, on ceilings, baseboards or around vents. Mold in air vents
- Water on the inside of windows in the morning. Condensation on windows
- Indoor humidity over 60% for weeks at a time. How to lower humidity
- Staining or peeling paint low on a wall, or swollen baseboards. Mold behind drywall
- A leak in the last few months, even one that looked dry fast. Mold after water damage
One sign on its own is worth watching. Two or three together usually mean something in the house is staying wet. That is what the check above adds up for you.
How to check your house for mold yourself
You do not need a test kit to start. Walk the house with a flashlight and a humidity meter, and check the spots that run cooler or wetter than the rest of the room:
- Around AC supply vents and the sheetrock next to them. Mold in air vents
- The bathroom ceiling over the shower. Mold on a bathroom ceiling
- The back wall of closets on an outside wall, and behind furniture pushed tight to a wall.
- Window sills in the morning. Condensation on windows
- Baseboards and the bottom of walls near tubs, sinks, the water heater and the AC closet. Swollen or stained means water. Mold behind drywall
- The underside of the attic decking. Attic mold
- The air itself. Leave a humidity meter in the main room for a day. Over 60% means the whole house is at risk. How to lower humidity
Real growth has texture and comes back after you wipe it. A stain or a dust line does not. Take what you found and run the check above. To keep it from starting, see mold prevention.
How the score works
The check looks at the things that keep a house wet, because moisture is the one thing mold needs that you can control.
- Humidity carries the most weight. Under 60% scores zero. 60–70% puts a home in the middle of the yellow zone, and over 70% puts it at the start of the red. Not knowing counts against you too, because in a humid climate an unmeasured house is often a wet one.
- An active leak, or growth that spreads or comes back after cleaning, sends the score straight to 100.
- A musty smell and small spots add to the score.
- The filter, attic and bathroom habits add smaller amounts. When humidity is under 60%, they cannot push a home out of the green zone on their own.
The scoring was built from what we see in South Louisiana houses and checked by other mold professionals. It is a warning system, not a diagnosis. For the full picture of what we find in real houses, see what causes mold in South Louisiana homes.
Common questions
How can I tell if I have mold in my house?
The most common signs are a musty smell, spots that come back after cleaning, water on the inside of windows, indoor humidity over 60% for weeks at a time, staining or peeling paint low on a wall, and a recent leak. One sign is worth watching. Two or three together usually mean something in the house is staying wet.
Is the Mold Risk Check a mold test?
No. It is a moisture check. It points to the conditions mold needs to grow. Only an on-site inspection can confirm mold, and identifying what it is takes a laboratory.
What indoor humidity is too high?
Above 60% for weeks at a time, mold can grow on ordinary surfaces with no leak anywhere. Under 50% is comfortably safe.
How can I tell if it is black mold?
Not by looking. “Black mold” is a name for at least three unrelated molds, and one mold can change color as it grows. Only a lab can say what it is. What you can check is whether it is growing: real growth has texture and comes back after you wipe it. Either way the fix is the same: find the water. Black mold removal
Do you save my answers?
We save the answers, the score, and the ZIP code if you enter one, so we can see where moisture problems are most common. We do not ask for or save your name, email, phone number or address.