Phone answered 24/7 · St. Petersburg, FL and nearby communities

Call 24/7: (727) 308-5518
Boca Ciega Bay Water ResponseWater Damage Help · St. Petersburg, FL

What Causes Musty Smell in a Home After Flooding?

Last updated October 26, 2026

Call Now (727) 308-5518

The short answer

Moisture Trapped in Building Materials

When floodwater soaks into porous materials like drywall, wood studs, and particleboard, it lingers long after the surface feels dry. The water saturates the core of these materials, and without proper drying, the dampness persists for days or weeks. That trapped moisture is the primary fuel for the musty smell you notice.

Carpet and padding are especially prone to holding water. Underlayment acts like a sponge, keeping the area wet even if the carpet top feels dry. Baseboards, insulation, and even subflooring can also stay damp, releasing a persistent odor that seems to come from nowhere.

Mold and Mildew Growth

Mold and mildew thrive in damp, dark spaces, and a flooded home offers ideal conditions. Within 24 to 48 hours, spores can begin to colonize on wet surfaces, releasing volatile organic compounds that create that characteristic earthy, musty smell. The odor is often the first sign that mold is actively growing.

Mildew tends to grow on flat surfaces like walls and tiles, while mold can penetrate deeper into materials. Even if you cannot see visible growth, the smell can indicate hidden mold behind walls or under floors. If you or anyone in your home feels unwell from the odor, see a doctor.

  • Drywall that feels dry on the surface but is wet inside
  • Carpet padding that stays damp for days
  • Wood floors that absorbed water through gaps
  • Insulation in walls that holds moisture
  • Baseboards and trim that trap water behind them
  • Furniture cushions and upholstery that soaked up floodwater

Humidity and Poor Airflow

After a flood, the air in your home often stays humid, especially in a climate like St. Petersburg's humid subtropical weather. High humidity slows the drying process and keeps moisture in the air, which can make the musty smell stronger. Without good airflow, damp pockets develop in corners, closets, and behind furniture.

Opening windows and using fans or dehumidifiers can help, but they only work on surface moisture. Hidden dampness in walls and floors continues to release humidity, so the smell may return even after you air out the space. Addressing the source of the moisture is key to eliminating the odor.

What You Can Do

Start by removing standing water and wet items as soon as it is safe. Pull up carpet and padding if they are soaked, and cut away wet drywall a few inches above the waterline. Use fans and dehumidifiers to dry the area, but remember that porous materials may need to be completely removed to stop the smell.

If the odor persists, you may need professional help. Local water damage pros can assess the extent of the damage and perform thorough cleanup, including removing affected materials and treating the area. For a detailed evaluation of your home, a water damage inspection can identify hidden moisture sources.

  • Remove wet carpet, padding, and drywall promptly
  • Use fans and dehumidifiers to speed up drying
  • Check behind baseboards and under cabinets for dampness
  • Clean surfaces with a mold-killing solution
  • Throw away items that cannot be fully dried
  • Keep the area ventilated until completely dry

When to Call the Pros

If the musty smell is strong or persists after your own drying efforts, the damage may be deeper than it looks. Floodwater can seep into wall cavities, under flooring, and into insulation, which is hard to dry without specialized equipment. The pros can use moisture meters and industrial drying tools to reach hidden areas.

Professional flood damage cleanup usually involves removing affected materials, treating surfaces, and setting up proper drying conditions. This work can help stop mold growth and reduce the odor. If you live in St. Petersburg, consider contacting local water damage pros for a thorough cleanup. Policies vary, and your insurer decides what is covered.

Talk to someone now

Phones are answered 24/7 for St. Petersburg and nearby communities.

Call Now (727) 308-5518

Frequently asked questions

Will the musty smell go away on its own?

Sometimes, if the area dries out completely and no mold has taken hold. But if moisture stays trapped in materials, the smell can linger for weeks or months. Removing wet materials and improving airflow are the right ways to get rid of it.

Is a musty smell dangerous?

The smell itself is not always harmful, but it often signals mold growth, which can trigger allergies or respiratory issues. If you feel unwell, see a doctor. It is sensible to address the moisture and mold promptly to protect your health.

Can I just paint over the musty-smelling wall?

Painting over a damp or moldy wall will not solve the problem. The moisture and mold will continue to grow underneath, and the smell will eventually come through. You need to remove the affected drywall and fix the moisture source before repainting.

Call Now (727) 308-5518