ply under tiles

[iasku]

As I have not had any replies to my 'concrete over ply' question I thought I would try this.

Can anyone advise what the minimum thickness of Marine/External Ply would be to ensure maximum stability for overlaying tiles (or similar).?


(By the way, breezer, if you read this, I'm not complaining about lack of response just thought I'd try again)

Cheers

 

[StickyP]

For maximum stability, install two(2) layers of 18mm Ply on joists at centres no more than 450mm apart. The sheets are to be glued and screwed.

This is the American system for "structural timber flooring"

In NZ we will acept single layer ply for internal domestic work, then use a 2-pack flexible adhesive, but most installers add a layer of 6mm Tile & Slate underlay. (fibre-cement sheeting)

If you are starting from scratch, install 18mm Fibre-cement sheet. It is more rigid, not prone to moiture damage and, unfortunately, much dearer (here anyway).

Good luck

 

[masona]

Can anyone advise what the minimum thickness of Marine/External Ply would be to ensure maximum stability for overlaying tiles (or similar).?

I don't think there is a minimum thickness, most common thickness size is 6mm (1/4") for floor tiling and screw down every 9".

3mm ply would be too flexible.

 

[chappers]

if you are laying it over existing floorboards then 3mm would probably be a bit thin as masona says you are trying to even out the irregularities in the boards, but if the boards are nice and level you will probably be ok with 3mm.make sure the boards below are well screwed down the screw to these at 300mm centers maybe less for 3mm