The short answer
What Causes Mold on Drywall
Mold needs three things to grow: moisture, warmth, and a food source. Drywall's paper surface is that food. When water soaks into the wall from a leak, flood, or even condensation, the paper stays damp long enough for mold to take hold.
In a semi-arid climate with cold snowy winters and hot dry summers, indoor humidity can spike from cooking, showers, or a poorly vented dryer. A slow pipe leak behind a wall is another common culprit. If you live in Orem, keep an eye on areas near bathrooms, kitchens, and exterior walls.
- Plumbing leaks from supply lines or drain pipes
- Roof leaks that run down inside walls
- Condensation on cold pipes or poorly insulated walls
- Flooding from heavy rain or a burst water heater
- High indoor humidity without enough ventilation
- A damp crawlspace or basement that wicks moisture upward
How to Spot Mold on Drywall
Look for black, green, or gray spots that spread in patches. The mold often appears as fuzzy dots or streaks along seams, corners, or baseboards. A musty smell is a strong clue, even if you cannot see visible growth yet.
You can also feel the wall for soft spots or bubbling paint. These signs suggest the drywall has absorbed water and the paper is breaking down. If you notice any of these, act fast because mold can spread behind the surface where you cannot see it.
Why You Should Act Quickly
Mold can start growing within 24 to 48 hours after moisture appears. The longer the drywall stays wet, the deeper the mold penetrates. Once it gets into the gypsum core, the entire panel may need to be removed.
Mold also releases spores into the air, which can irritate your eyes, nose, throat, or lungs. If you feel unwell, see a doctor. Do not try to scrub mold off drywall; that often pushes spores deeper into the material.
When to Call Local Water Damage Pros
If the mold covers a small area, say less than a square foot, you might handle it yourself with proper safety gear and a mold-killing cleaner. But if the mold is widespread, or the water source is hidden, you need help from local water damage pros.
The pros have moisture meters and infrared cameras to locate hidden dampness. They can also dry out the wall structure with industrial dehumidifiers. For large mold growth, a mold professional may be needed to test air quality and guide safe removal.
- Mold covers more than a few square feet
- You cannot find or stop the water source
- The drywall feels soft or crumbles when touched
- Someone in the home has breathing issues or allergies
- The wall has been wet for more than a couple days
- You see mold on both sides of the wall or in multiple rooms
How to Prevent Mold on Drywall
Fix leaks quickly and dry any wet areas within 24 hours. Use exhaust fans in bathrooms and kitchens, and keep indoor humidity below 50 percent. You can buy a hygrometer to measure it.
Check your plumbing and roof regularly, especially after heavy storms. If you have a basement, consider a dehumidifier. And if you ever have a flood, remove wet drywall promptly to stop mold before it starts.
Water damage does not wait
Call (801) 876-1119 any time, day or night, and describe what happened.
Call Now (801) 876-1119Frequently asked questions
Can I just paint over moldy drywall?
No. Painting over mold does not kill it. The mold will keep growing underneath and eventually show through. You must remove the mold or replace the drywall. For small spots, clean with a mold-killing product, but for larger areas, removal is safer.
How do I know if the mold is toxic?
Any mold can cause health problems, especially for people with allergies or asthma. You cannot tell by color or smell. If you are worried, see a doctor if you feel unwell. For peace of mind, a mold professional can test air quality, but no test is required to start cleanup.
Will my insurance cover mold damage?
Policies vary, and your insurer decides what is covered. Some policies cover mold if it results from a sudden leak, but not if it comes from long-term humidity. Check your policy and ask your insurer directly. Keep records of the damage and any repairs.