tiling on chipboard

[goodenough]

hi a customer asked me to tile her kitchen floor its about 20m2 and has a chipboard floor onto joists, as this is my first time doing this type of floor was wondering would i be better off laying plywood onto the chipboard first , its not a new build, but the chipboard is in good condition cant be sure if it was primed when it was layed and was going to use bal flexi set adhesive and grout the tiles are 330*330mm ceramic Thanks for any help

[grumpygrouter]

The thing to be considering is if the floor is strong enough without overboarding. 20m2 is reasonably large and would probably benefit from strengthening with 18mm ply.

As we can't see what you can see though it would be your call. If you lay 18mm ply, on top of the chipboard screwed to the joists a t 300mm centres and you overboard with the ply across the chipboard direction and screw this through into the chipboard surface then you can get away with single part flexible adhesive. You will need to seal the back face and edges with BAL Bond SBR first before laying.

if you are not going to overboard the you will need to use something like BAL Fastflex which is a 2 part adhesive or Ardex 7001. Which every way you go , always check out the adhesive manufcturers instuctions BEFORE you lay your ply as they can differ with regards to sealing/priming.

[cjbombero]

With a floor that size I would ply the floor. As Grouters has already mentioned going straight onto chipboard will require a highly flexible adhesive like BAL Fastflex. The cost implications are massive, depending on you supplyer you wont get Fastflex much cheeper than £40 for both parts (powder & liquid) This only covers approx 3 sq m of floor! You also need a solid bed tipped trowel (another £15)

Take grouters advice, board the floor out. It will be cheaper, easier and faster.

cjbombero

[CJ]

Be tempted to 12mm hardibacker it myself........glued and screwed. Then flexi cement/grout

[newbie2]

You will need to seal the back face and edges with BAL Bond SBR first before laying.

Grumpy, Can explain why this is necessary? Does it help with the adhesion of the overboarding, or is it to ensure that the overboard is waterproof?
Does the top face also require a coating of SBR before tiling?

Thanks,
Steve

[Dave]

The sbr helps with the moisture resistance of the ply.....and no you do not seal the face of the ply when using BAL adhesives.....