Problem: Tiling on wooden floors

[Daniel A]

Hi guys,

Advise would be appreciated-

Tiling on 22mm chipboard, over-plyed with 9mm boards, with 1 part adhesive but some tiles appear to be de-bonding.

Some slight movement in the floor, would a 6mm cement board help this? Or any other suggestions?

thanks

 

[Gazzer]

9mm ply is not good enough, it should be 15mm min.
But you need to sort that movement out before laying cement boards as they wont add any strength.

 

[Bubblecraft]

9mm ply is fine screwed every 150mm2 & ply fully primed with an SBR. Over sheeting isn't going to solve the problem. You'll need to source where the movement is on the original subfloor if any. Good chance they are de-bonding due to insufficient amount of screws, not being primed correctly or a non flexible adhesive used.
How far apart were the screws & what primer did you use?

 

[macten]

Sorry bubble but I'm with Sir Ramic - 9mm ply isn't thick enough.
Surface of ply shouldn't be primed, just the back and edges.
Get chip board solid then over board with cement sheet and do away with that nasty timber substrate.

 

[Bubblecraft]

I agree that cement board would be best but there is already 9mm ply in place and nothing wrong with that if fitted correctly. If cost isnt an issue, re-sheet with cement boards. Didn't mean to say prime surface. Corrected now. Oops!

 

[bugs183]

As above, sort out any movement, then cement board, bedded into adhesive and screwed down with the appropriate metal washers.