How to Fix a Wet Subfloor in a Bathroom

Remove the tiles over the damaged area of the subfloor. Pry off linoleum or vinyl tiles with a putty knife, using lacquer thinner to dissolve the tile adhesive. Chip off ceramic tiles using a masonry hammer and cold chisel. If the ceramic tiles are too difficult to remove using this method, you will need to call a professional to have them removed without doing further damage to the bathroom.

Place the tiles in a well-ventilated room to allow them to dry. Dispose of tiles that were damaged during the removal process. Wipe mildew from the tiles and the subfloor with a 25 percent solution of white vinegar and water.

Piece raised bubbles in the subfloor with a small nail and masonry hammer.

Allow the subfloor to dry. Run a fan in the bathroom or open windows to increase circulation. Place an electric heater in the room to accelerate the drying process.

Check the subfloor's moisture level with a commercial moisture meter before replacing tiles. If it is 12 percent or lower, walk on the subfloor. It should feel hard and solid. If the subfloor feels spongy, it may need to be replaced entirely.

Prepare the dried subfloor for tile application. Scrape and sand the floor to remove residual tile adhesive and to create an even surface. Vacuum away dirt and sanding dust.

Spread tile adhesive on the floor, using a putty knife, and replace the tiles.