Please help settle a debate - would you screw plywood down?

[KeRa]

My father and I had a debate earlier, whether it is correct to screw a 6mm sheet of plywood to a concrete floor which has wooden panels covering the pipes or to leave it unfixed. The ply will then be covered with ceramic floor tiles.

He was of the opinion that screwing it down would make it difficult if it ever needed to be taken up and that the weight of the tiles would hold it down.

I felt that having laid it down and walked on it, that it flexed under foot and this could lead to the tiles coming loose with time, especially as the floor is made up of two pieces in order to be able to fit it.

 

[mattysupra]

why you putting 6mm plywood over concrete base? You should be using the correct smoothing compound not plywood.

 

[mattylad]

If you just have to have it there, then yes screw it down.
This will stop any future problems with warping etc.

But it would probably be better to use a self levelling compound etc if you needed extra height.