www.ultimatehandyman.co.uk

Hey folks

I'm just about to tile our dining room / kitchen its approx 20sqm. The floor is new chipboard on new joists with about 1000 noggins / dwangs - it felt like that! and I have laid 9mm ply onto it screwed at 150mm centres.

When I tiled my bathroom over 5 years ago I used tops tiles flexible onto wood adhesive and was pretty impressed the floor wasn't great and the re has been no cracking.

The tiles for this are 12mm and are expensive so don't want to get it wrong, what adhesive would you guys recommend and do I need to put down a primer?

Finally what trowel depth would you recommend?

many thanks

9mm Ply isn't suitable. It's prone to warping from the moisture of the adhesive and if it bridges troughs and peaks in the sub floor it isn't thick enough to offer a solid base without flex. You say it is on to a new chipboard floor so that may not be so much of an issue but I still wouldn't use it due to the warping factor.

It's true that many floors have been tiled on to 9mm ply without issue, but it is not without risk and in addition the general quality of ply available from builders merchants is not as good as it was even 5-6 years ago.

Much more suitable would have been 6mm tile backer boards.

If you do go ahead and tile anyway then any flexible cement based adhesive will be suitable although in many cases the ply will need to be primed first (in fact the underside of the ply should have been primed before laying it but that's a whole other story).