Correct Tile Adhesive

[Alan McNally]

Something else I forgot to ask...

The tiles are 600x300 what would be the standard spacing between tiles? I have read that 3mm is the minimum?

Also any recommendations for a decent quality grout?

Thanks again.

 

[Rookery]

Priming the back and edges of the ply is to prevent moisture ingress, not to prevent the adhesive drying too quickly. In any event, BS calls for a ply overlay to be minimum 15mm thick and of WBP or Marine grade, so your overlay is already under spec and possibly not the best quality. I would take it up, overboard with Hardie glued and screwed and fix tiles with Mapei Keraquick using 3mm spacers, grouting with Mapei UCP. Alternatively I would fix with BAL Rapidset Flex. I've never used Tilemaster but it gets good reviews. I might use an uncoupler too depending on the size of the floor and how stable I felt it to be.

 

[Alan McNally]

Hi,

Thanks for your advice. I have been thinking about what you say regarding water ingress to the ply, surely if there was moisture present enough to cause an issue with the ply then even if it was primed on the back egde I would still have a problem, after all if the ply is securely fixed to the tounge and groove so if moisture was present would the tounge and groove not react to it and take the ply with it causing shrinkage/expansion anyway?

I have read through the prep guide for the tile master s2 adhesive and they say 12mm ply is fine for overboarding the existing floor?

Like I said previously if I need to replace the ply then I will do it. Appreciate all the advice but there seems to be quite a difference of opinion with how best to proceed.

Thanks,

Alan.

 

[Andy Allen]

Main issue you get when tiling a wooden floor is deflection.......it has to be as solid as you can get it with no bounce.
I've seen many failed floors that have been tiled on ply or chipboard mainly a combination of to much bounce and the adhesive not sticking to the wood for one reason or another.
You could just overboard the ply with 4 or 6mm cement boards if extra hight isn't an issue.....this would be belt and braces approach...
If I had to tile on ply I would use bal single part fast flex and bal wide joint grout with GT1 admix.
And use the adhesive as per instructions and back skim the tile .

 

[Alan McNally]

Hi Andy,

Thanks for the reply...

I have checked out the BAL adhesive you mentioned, I wasn't ready for the £45 per 12.5kg price tag haha! I know you get what you pay for but 😱

I can get the tile master ultimate s2 for a good price, have you had any experience with it? If I really need to go with the cement backer boards I think I'll just lift the ply and replace it to keep the height difference between rooms to a minimum.

One thing I didn't mention before was the when I gutted the room for renovation I removed tiles from the same floor. The ply that was down was only thin (3mm I'd say) and just nailed to the tounge and groove, tiles appeared to be porcelain but I don't recall seeing any cracked tiles or grout so hopefully that puts me in a good position.

Cheers,

Alan.

 

[Alan McNally]

Ok, I've decided to lift the ply and replace with a backer board. Just a quick question, I was looking at the 6mm marmox board. There are a lot of posts advising the boards to be fixed to the sub floor using both adhesive and screws but the marmox instructions say adhesive OR screws so I was just going to screw it down. Is this ok?

Thanks.

 

[Andy Allen]

The adhesive will fill any voids and make a much better job..

 

[Alan McNally]

Ok Andy thanks. Can you please recommend the correct adhesive for bonding the backer boards to the tounge and groove and also would I still use an S2 type adhesive for bonding the tiles or would this be overkill?

Thanks again.

 

[Andy Allen]

Any cement based adhesive to stick down the boards it doesn't have to be expensive as it's just to fill in the voids just make sure you screw them down as well.
And yes I would still use an S2 type of adhesive to tile.

 

[Alan McNally]

Ok Andy, thanks again.