How to Fix a Wet Subfloor in a Bathroom

eHow may earn compensation through affiliate links in this story. Learn more about our affiliate and product review process here.

Things You'll Need

  • Putty knife

  • Lacquer thinner

  • Masonry hammer

  • Cold chisel

  • White vinegar

  • Small nail

  • Portable electric heater

  • Moisture meter

  • Floor scraper

  • Sandpaper

  • Vacuum cleaner

  • Tiles

  • Tile adhesive

Dry out a wet bathroom subfloor to prevent rotting.

Overflowing toilets, bathtubs and sinks in bathrooms can cause water to seep underneath tiles and saturate the subfloor. When moisture becomes trapped in a subfloor, it can cause tiles to bubble and warp. Over time, trapped moisture can cause the subfloor to rot, compromising the bathroom's structural integrity. If your bathroom's floor is warping due to moisture saturation, you must remove the tiles to let the subfloor air out.


Step 1

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.

Video of the Day

Step 2

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.

Step 3

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


Step 4

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.

Step 5

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.


Step 6

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.

Step 7

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


If the subfloor is rotten, it is best to replace it to avoid further structural damage.


Video of the Day

references & resources

Report an Issue

screenshot of the current page

Screenshot loading...