How to Repair the Bottom of a Vanity Cabinet

The bottom of a vanity cabinet can be a damp and dark, especially if it's under a sink that is leaking. Water and mold can take a toll on any wooden surface, but vanity bottoms are often made of particle board, which is especially susceptible to rot and water damage. When holes develop, you usually have to replace the entire bottom, because there isn't enough support for a patch. Cutting and installing a replacement bottom is straightforward, but getting the old bottom out without damaging the cabinet can be tricky.

Bathroom vanity bottoms often get wet or moldy.
  1. Unscrew the cabinet door hinges and remove the doors.
  2. Drill a 1/2-inch hole in the vanity bottom near the center. Insert a jig saw blade and cut a large hole out of the center of the board.
  3. Insert a pry bar through the hole and wedge it into the space between the bottom and one of the side supports. Pry the bottom up until the nails holding it pop loose. As soon as the heads are high enough, pry the nails out with a hammer. Remove all the nails from one side, then remove them from the other in the same way.
  4. Wedge the pry bar between the bottom and the front trim and pry the bottom away. Lift it out as soon as it is free from the nails that were holding the trim. Tap the nails out with a hammer when the board is removed and pull them out from the front of the trim with a hammer.
  5. Place the bottom on a sheet of 5/8-inch plywood and trace around it with a pencil. Cut out the outline with a circular saw. Use a jig saw to cut notches in the corners to match the notches that were on the old bottom.
  6. Place the new bottom in place on the side supports and nail it down with 8d finish nails. When it is secure, nail the trim to the bottom, using 8d nails and inserting them in the holes from which you removed the old nails.
  7. Sink the heads of the trim nails with a nail punch and fill the holes with wood filer. When the filler dries, sand it with 120-grit sandpaper and repaint the trim. When the paint dries, replace the vanity doors.

Things You Will Need

  • Screwdriver
  • Drill
  • 1/2-inch drill bit
  • Jig saw
  • Pry bar
  • Hammer
  • 5/8-inch plywood
  • Pencil
  • Circular saw
  • 8d finish nails
  • Nail punch
  • Wood filler
  • 120-grit sandpaper
  • Paint


  • If the bottom is screwed in place, you can remove it by unscrewing the screws, so you won't need to cut a hole. You'll still need to use the pry bar to pry the trim loose.
  • When you remove the bottom, check the side supports for water damage and replace them if they don't appear strong enough to support the new bottom.

About the Author

Chris Deziel has a bachelor's degree in physics and a master's degree in humanities. Besides having an abiding interest in popular science, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.

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