Installing Slate Over A Plywood Floor

by Mike
(illinios)

Question:
Can you lay the slate over a plywood floor or do you have to install cement board over the plywood?

Answer:
You can lay on top of plywood as long as it is WBP (water boil proof) Marine Plywood, this has been treated & is much stronger than standard plywood.

It is also recommended that a minimum of 15mm marine plywood is used & that the floor does not flex, if it does then a more solid method would be to cross lay 9mm WBP Marine Plywood on a horizontal direction screwed down at every 300mm intervals & then overlay a second layer of 9mm WBP Marine Plywood on a vertical direction screwed down again at 300mm intervals, remember to use a flexible grout & adhesive.