Plywood Base for Tiled Bathroom Floor

[shelby3]

Hi I'm going to be laying a plywood base onto chipboard before I tile the bathroom floor.

When I did a previous bathroom 1 whole sheet was sufficient (not cuts).

But in this bathroom I'm going to need to put 3 sheets down to cover the floor. Is there an issue doing this? i.e. i'm assuming each sheet might contract and expand at a different rate and thus cause movement to split the tiles/grout?

also i used exterior grade plywood last time? is that advisable? or is structural plywood the right thing to use?

 

[pinenot]

The movement of plywood is so minuscule that it can be ignored. Square joint are normal, some tilers put a plastic scrim cloth over the joints, some don't!.

 

[shelby3]

Thanks pinenot!

 

[dazlight]

Exterior ply mate. Screw down every 6" and on joints even 4"

 

[pinenot]

Exterior ply mate. Screw down every 6" and on joints even 4"

Better with 1" ring shanks, made for the job...pinenot

 

[dazlight]

On 18mm ply? I only use ring nails on 9mm or below myself.