Can Moldy Subfloors Be Cleaned, or Must It Be Replaced?

If mold is only on the surface and the subfloor is still solid, cleaning can work. The pros may use a HEPA vacuum, antimicrobial cleaner, and a drying process to remove surface growth. This is more likely on plywood that has not been soaked for long.

But cleaning only works if the wood is dry and firm. If you press a screwdriver into the wood and it dents easily, or if the mold has a musty smell that lingers, cleaning will not fix the problem. The mold can stay alive in the wood fibers.

• Surface mold on solid plywood might be cleaned
• Wood must be dry and firm after cleaning
• A moisture meter helps decide if drying is enough
• If mold returns, replacement is needed

Start with a visual check. Look for dark spots, staining, or a fuzzy texture. Then probe the wood with a screwdriver or awl. If it sinks in easily, the wood is compromised. A moisture meter can also show if the wood is still wet inside.

If you smell a strong musty odor even after the surface looks clean, mold is likely deeper. Also, check for visible warping or buckling. Any of these signs point to replacement, not cleaning. When in doubt, a water damage inspection can give you a clearer answer.

Once the subfloor is clean or replaced, fix the source of moisture. Check for leaks in plumbing, roofing, or the foundation. Keep the crawlspace or under-house area dry and ventilated. A dehumidifier can help in humid months.

If you live in Frisco, remember the humid subtropical climate with hot summers and spring hail and thunderstorms. That means moisture can come from many directions. Regular checks after storms can catch problems early before mold takes hold.