Replacing floor under sink will take some carpentry skills

Q: Some time ago, I apparently had a leak under my kitchen sink. The leak was fixed, but I am left with the cabinet floorboard, which looks gross the way it is warped. I would like to replace it, and I need to know how to do it.

A: I remember back in the day my mother used to line the cabinets with self-adhesive paper. This is still available, but I don’t think it’s nearly as popular (or groovy) as it once was.

Anyway, the nice thing about this plastic sticky stuff was that if anything leaked on it, the wood cabinet floor couldn’t absorb the water and sustain damage. If you ask me, I think the paper looks pretty damaging by itself.

At some point, I’m sure everyone will find they have a leak under the sink that, in turn, will lead to some degree of water damage on the floor of the cabinet. Replacing the piece will take a few hours and some light carpentry work.

You first have to remove the old floorboard, which will be the easy part. You’re going to have to deal with the vertical support piece that separates the doors of the cabinet. The vertical support won’t come into play when you remove the old floorboard, but when you install the new floorboard, it’s going to get in the way.

The floorboard may be damaged enough that it almost disintegrates in your hand, or you may have to cut it and pull it out. You might even have to cut or drill a hole in it and then saw it in half. Once you get the board out, you will find a few supports under it to add stiffness so that the weight of your trash can and dishwashing soap doesn’t make it bow.

A big reason the cabinet floorboard gets damaged so easily is that it is usually made of particle board. Some boards have a thin film of faux wood grain material on them.

I would replace the board with melamine, which comes in ¾-inch thickness and is essentially a thick white plastic covering over particleboard. It cuts easily with a saw and is ideal for use under sinks.

Replacing the board can be a pain. The main problem is that the vertical support is in the way of sliding a new board into place, so you are forced to replace the board in two pieces.

Cut the boards to fit, apply some construction adhesive to the supports, and squish each piece into place. You will have a seam down the center of the floorboard, but who is going to see it?

The seam is in the exact spot where any future dripping water would puddle, so add a bead of caulking down the seam to prevent water intrusion.

For perfectionists, you can replace the board in one piece if your cabinets are built for it. After you remove the old floorboard, you will notice that the cabinet front juts out and that there is a space between the front of the cabinet and the toe kick (the vertical visible piece of wood just below the base of the cabinet where you would stub your toe if you slid your foot into the cabinet).

You should be able to remove the toe kick — it is usually a thin piece of wood attached to the floorboard supports — and then move the floorboard supports so that they are laying down or out of the way. If you can do this without too much difficulty, you can nail a ledger board across the back wall of the cabinet. Then you can slide the floorboard underneath the cabinet, laying it on top of the ledger board.

Swing the floorboard up and replace the floorboard supports to keep it in place, and then replace the toe kick. You can use adhesive and nails along the way to keep everything solid.

If all this sounds like too much work, maybe you can revisit the 1970s and roll out the self-adhesive paper.

Mike Klimek is a licensed contractor and owner of Las Vegas Handyman. Questions may be sent by email to handymanoflasvegas@msn.com. Or, mail to 4710 W. Dewey Drive, No. 100, Las Vegas, NV 89118. His web address is www.handymanoflasvegas.com.