How to Know if Floor Wood Is Rotted or Wet

Examine the surface of the wood, looking for bubbling or flaking. If the wood shows evidence of bubbles or if the grain flakes, wood rot has already set in.

Dig slightly into the wood with your fingernail. Wet wood will remain firm and intact because the water remains at the surface, but rotted wood will instantly flake, feeling almost powdery.

Drill into the wood in an out-of-the-way area using a drill fitted with a one-sixteenth-inch bit. Drill to a depth of about one-half to one inch.

Examine the wood filings that lift up with the drill bit, looking for hard, dry wood or soft, dark wood. Solid wood will appear fresh and hard while rotted wood will appear dark, soft and flaky.