Laying BIG tiles on a crap chipboard floor????

[boisty]

Hi Folks

I've recently been asked by a mate to lay some of those bloody 900mm tiles from B&Q (sorry, I'm new on here, is it ok to use the those two letters here? :dizzy2: ) onto his poorly laid 18mm p4 floor which has wet underfloor heating running off the central heating system.

Without wishing to lift the floor entirely could I get away with overlaying the floor with 9mm ply or would it be best to lift the existing floor and relay with 22mm p4/p5 chipboard.

Any advice or other ideas will be gratefully received.

 

[Gazzer]

Use a 6mm tile backer board such as Hardibacker or No More Ply. Fix with adhesive and screws and tile away. That would be my minimum spec and i wouldnt use ply at all.

 

[Stan001]

and wash the B&Q tiles before you use them