Tiling on floorboards

[bass]

I have done quite a lot of wall and floor tiling over the last 4 years and have never tiled direct to floorboards. I normally plywood the floor 9mm and no less but this job i am doing cant be overboarded as this will leave a massive step. the original mosaic tiles were bedded straight to these floorboards using, i suspect a two part flexi adhesive (bomb proof) and the customer wants natural stone mosaic tiles . Is there a special latex self leveling compound that i can use prior to tiling as the floorboards will need more fixings putting in before tiling. i did notice a crack on the original mosaic grout line and once lifting the tiles realised the floorboard was slightly bouncing, but i will address this. would apreciate any advice .woulld like to add that this was suggested by work colleague and would like to here any other advice.

 

[markfin24]

One answer might be to use a backer board. You could use a 6mm board fixed to the existing timber floor as manu recoms, being inert it won't move so no cracks in tiles. It still adds to floor build-up, but not as much as ply.

 

[andyinthepeaks]

Mmmm I have used the Unibond ready mix adhesive/grout for wooden floors, but only over ply though it claims to be o.k. for direct to floorboards.

If was going to try, Id probably puts screws in all the floorboards to fix them more firmly to the joists, sand the boards if required then try the wooden floor adhesive. It was quite expensive but I've had no problems with it

 

[Richard C]

12mm WBP is the minimum you should be using to overboard; BS & all the major tile adhesive manufacturers recommend 15mm. personally I prefer to replace the floor where I can with 18-25mm WBP ply depending on joist size/pitch/span; this avoids the threshold problem. You could use backer boards but 6mm is a bit on the slender side & I wouldn’t risk it.

You should never use ready-mix addy on floors let alone a combined addy/grout & you won’t find many pros using that one. If you want it to last, only use quality trade products like BAL, Webber, Mapei, Ardex etc. of the correct type; cement based Rapidset flexible or a single part flexible is adequate for suspended timber floors in most cases unless you have a dodgy floor but the latex based or epoxy addy is far more expensive; it costs less to beef up the floor.

Take some time out to read through the Tiling Forum archive posts, lots of stuff in there from myself & 2/3 other pro tillers in there.

 

[kevd]

you could life the floor boards in this room and replace with 25mm WBP ply? Though I am not sure if the same thickness ply is more bendy than the same thickness in pine floorboards (thinking 18mm here not 25)!

How about using a Ditra matting on top and belt and braces - this will help reduce and cracking in the grout due to movement of the floor beneath.

 

[Richard C]

you could life the floor boards in this room and replace with 25mm WBP ply? Though I am not sure if the same thickness ply is more bendy than the same thickness in pine floorboards (thinking 18mm here not 25)!

How about using a Ditra matting on top and belt and braces - this will help reduce and cracking in the grout due to movement of the floor beneath.

Replacing is always my preferred approach &, in most cases, 18mm WBP is sufficient for bath/shower rooms but it does depend on the floor construction; I almost always tile straight over the ply. Ditra matting is a decoupling membrane; it’s intended to control moisture & accommodate differential/lateral floor movement rather than reduce flex in the floor. The floor must still be rigid & for that you should either replace it with something more suitable, reinforce the joists or overboard with ply or a proprietary backer board like Wedi or Marmox etc.