Plywood to the interior size of the sink base.
How to fix cabinet floor under sink.
In from all four edges.
Remove the old swollen floor.
If left unrepaired the leaks can cause significant damage to the cabinet floor by promoting wood rot warping and mold or mildew growth.
Then trace a cutting line about 3 in.
If you have a particle board floor underneath your sink that is showing signs of water damage you can tear it out and replace it to prevent the growth of mold.
Next cut a piece of 1 2 in.
Moisture destroys the particleboard most cabinets use for the floor below a kitchen sink.
The space beneath the kitchen sink is exposed to high levels of humidity and may even be exposed to water through leaky plumbing.
Damp rotten particleboard holds water which promotes mold and mildew.
Water leaks are a common occurrence under kitchen sinks.
Remove the drain lines and garbage disposer if there is one to get maneuvering room.