Hi guys need your help here ,its took a while but ive got my first job.
Its slate tiles on a plywood substrate, was wondering what was the best addy to use flexible, rapid set etc? , and do i need to prime the plywood first? also which brand is most cost effective? cheers jase.

Hi slate onto ply is ok. Best 12mm at least. Flexi will do. Prime under side of ply with appropriate primer , check spec on adhesive you buy to whether you need to prime face.
I use mapei kerraquick, no need to prime face. Mapei also do a primer suitable for plywood, it is called Eco Prim T

You should be considering the strength of the floor - is the ply layer direct to joists? If so this would need overlaying to avoid seam stesses and to decrease the floors deflection. The bigger the area even more so.

Hi, Further to the question asked by Jason35 above, can I ask for some similar advice?

I have to tile my son's 2mx1.7m (6'7"x5'7"), part of the floor is taken up by a 900mm (3') quadrant shower base. The existing floor is part large chipboard T&G type panels nailed down and the rest is plywood sheet screwed down. I intended to sand any uneven joints and cover it all with 5mm ply then seal it with yacht varnish to seal it, before tiling with 330mm ceramic floor tiles. Now I am not so sure!

Can I ask for some advice on the following:-
1. Should I also screw down the older nailed down chipboard floor?
2. Can I tile straight onto the floor without covering it with the 5mm ply?
3. If I have to cover it with 5mm ply, should I glue or screw the ply down?
4. For a small area like this what would you recommend for sealer/adhesive/grout?

Looks like the tiles will be coming from B&Q and it is pot luck on the night when asking for advice in-store. I would really appreciate any advice as tiling is not one of my favourite DIY tasks, I'd rather paint first and I hate painting! Thanks in advance.

Regards,
Ron.

hi mate,i wouldnt use 5mm ply its not suitable minimum i use is 9mm but 12 would be safer,,i also wouldnt varnish the floor to seal it you can buy tanking kits from most tile shops now which would be better if you have concerns about water ingress,and screw the ply down 150 centres grid formation nails wont suffice or glue. use a flexible adhesive and flexible wide joint grout for floors,,also i would prime the floor with a suitable primer...again most tile shops will advise you if your buying there products.if it is good old b and q your going to they now stock mapei adhesives/grouts this is the one you want. good luck

Hi, Further to the question asked by Jason35 above, can I ask for some similar advice?

I have to tile my son's 2mx1.7m (6'7"x5'7"), part of the floor is taken up by a 900mm (3') quadrant shower base. The existing floor is part large chipboard T&G type panels nailed down and the rest is plywood sheet screwed down. I intended to sand any uneven joints and cover it all with 5mm ply then seal it with yacht varnish to seal it, before tiling with 330mm ceramic floor tiles. Now I am not so sure!

Can I ask for some advice on the following:-
1. Should I also screw down the older nailed down chipboard floor?
2. Can I tile straight onto the floor without covering it with the 5mm ply?
3. If I have to cover it with 5mm ply, should I glue or screw the ply down?
4. For a small area like this what would you recommend for sealer/adhesive/grout?

Looks like the tiles will be coming from B&Q and it is pot luck on the night when asking for advice in-store. I would really appreciate any advice as tiling is not one of my favourite DIY tasks, I'd rather paint first and I hate painting! Thanks in advance.

Regards,
Ron.

You have in effect such a small area to tile, you may well get away with not over boarding at all. 5/6mm ply is, in my opinion, worse than tiling straight to the chipboard. If you want to overlay with something, consider a backer board like Hardiebacker 250. This is a waterproof cement board that you glue and screw to the existing surface and tile straight over the top.

Screw down you existing boards securely first and use a flexible cement based adhesive and grout.

have to agree with grumpy

Hi again,

Thanks for all the solid advice I've been given. I Have told my son what needs to be done and what to buy. He just needs to pick his tiles - black or white or both - I think his mum will decide for him? Thanks again.