tiling on chipboard floors

[harry030907]

i want to tile my upstairs bathroom floor but it is chipboard what adehsive should i use and what happens if the boards arent flat?

[grumpygrouter]

i want to tile my upstairs bathroom floor but it is chipboard what adehsive should i use and what happens if the boards arent flat?

Chipboard floors can be problematic Harry. If there is any doubt about the integrity of your floor regarding rigidity and conditon of the boards it is highly recommended to overlay 18mm WPB ply and tile onto that.

This will give you a good surface to tile onto and also add strength to the floor. Main drawback is that you will have a "step" of around 30mm between your transition at the doorway.

To overlay with ply, lay the boards perpedicular to the run of chipboard (after ensuring the chipboard is securely screwed to your joists) and screw through INTO not Through the chipboard with not more than 30mm long screws. Do this at no more than 300mm centres, preferably less if you can. You can then tile with single part flexible adhesive. ( you will need to seal the back face and edges of the ply before laying).

[brian c]

In addition to above just check wih the adhesive manufacturer regarding priming the ply as there seems to be different guidelines at the moment with various manufacturers.