Mold on walls is one of the most common things homeowners search for, and one of the most commonly mishandled. Sometimes it’s a light film on the paint that cleans right off. Other times it’s growing inside the drywall, and no amount of scrubbing will fix it. Here’s how to tell which one you have.
Step 1: Figure Out What You’re Dealing With
| Likely surface mold | Likely in the drywall |
|---|---|
| Small spots or a light film on paint | Stains that bleed back through after cleaning |
| Wall feels firm and dry | Wall feels soft, bubbled or crumbly |
| Near a steamy area like a bathroom | Near a leak, window, AC closet or past flooding |
| Small area | Larger than about 10 square feet |
How to Clean Surface Mold Off a Painted Wall
- Protect yourself. Gloves, eye protection and a well-fitting mask. Open a window or run a fan blowing outside.
- Lay down a drop cloth or old towel below the area.
- Use a damp, not dripping, cloth with dish soap and water, or 3% hydrogen peroxide or white vinegar. Don’t soak drywall; extra water makes things worse.
- Wipe gently and switch to clean cloths often so you aren’t spreading spores.
- Dry the wall with a fan and keep the AC running.
- Bag and toss the cloths when you’re done.
Never mix bleach with vinegar, ammonia or other cleaners. For more on which cleaner to use, see bleach vs. vinegar vs. hydrogen peroxide.
Why You Can’t Clean Mold Out of Drywall
Drywall is paper on both sides of a gypsum core. Once mold is growing in the paper and the core, it’s inside the material. The fix is to cut out the damaged section, usually with some margin around it, under containment so spores don’t spread, then dry the wall cavity and rebuild. Painting over it doesn’t work either; see can you paint over mold?
Always Ask: Where Is the Water Coming From?
Mold on walls in Florida homes usually traces back to one of these:
- A plumbing leak inside the wall or from a bathroom on the other side
- Windows or sliding doors letting in wind-driven rain
- An AC closet or drain line problem
- Condensation on cool exterior walls behind furniture
- Past flooding that wasn’t fully dried
If you clean the wall and skip the source, the mold comes back. For more, read how to find hidden mold and how to spot hidden water damage.
Free Visual Inspection in South Florida
FL Cleanup offers a free visual inspection with moisture readings and an infrared (thermal) camera to see how far moisture has spread inside your walls. If drywall needs to come out, we handle licensed mold remediation with proper containment. We answer 24/7, and hablamos español. Call 877-224-2532 or request a free visual inspection online.
About the author: James Rice-Peña is the owner of FL Cleanup and a Florida-licensed Mold Assessor (MRSA4035) and Mold Remediator (MRSR4158). He has worked in property restoration in South Florida since 2012, and FL Cleanup has earned 200+ five-star Google reviews.
