Tiling on plywood over concrete

[jlbradders]

I've been asked to tile a hallway and toilet which is currently concrete. The floor is not very level so i'll sort that with a levelling compound (i've not used this stuff yet but imagine it wont be anything tricky). They have then asked me to lay some plywood down before I start the tiling. The reason they give is that it will insulate more. Is this the right thing to do or should I advise that it will be better to go straight onto the levelled floor? thanks a lot.

 

[Richard C]

Self leveling screed OK but I would tile straight onto that if sound & no hint of damp. If they want better insulation, suggest an insulating tile backer board, you’re supposed to be the expert after all But if they have suggested you use ply (how thick?), they most likely won’t want to pay for it! Ply won’t make much difference to the insulation & difficult to judge why they want it; am suspicious of why they suggest it but difficult to judge without seeing it. If you do go with it, use WBP & seal the back & edges with SBR & it must be level & well fixed down but any hint of damp & the whole lot will fail anyway.

 

[tictic]

look into using insulation boards.

just dont see why they have said wbp ply... sounds nuts to me...
well you would have had to use 12/18mm ply so look into marmox boards.

 

[JohnD]

I imagine they have heard that it is good to use ply over an old floor before tiling; and did not realise this advice applies to old wooden floors. Ask them.

 

[jlbradders]

Cheers for the reponses, i've since discovered it's because the level needs to be brought up to the height in the lounge. They have already bought the ply (12mm) so guess they wont want to buy anything else. What would be the best way to fix down also? drilling and securing with screws? Adhesive wouldn't work would it? I'm a painter & decorator and have ony done tiling at home, so this is why i'm sounding a bit dim here.
Also what is SBR? and WBP (is that waterproof backing panel or something?). Thanks again

 

[Richard C]

They have already bought the ply (12mm) so guess they wont want to buy anything else.

I hope its WBP (see below), I wouldn’t touch it if not.

What would be the best way to fix down also? drilling and securing with screws?

Yes & fix it down well.

I'm a painter & decorator and have ony done tiling at home, so this is why i'm sounding a bit dim here.

Forgive me if I seem a little blunt but from the questions your asking, maybe you should stick to painting & decorating How long is the hallway? What tiles are they? What do you intend using by way of adhesive/grout? If you’re doing this tiling job for payment, you’re obvious lack of experience is going to lay you wide open to all sorts of problems & if it goes wrong, it could end up costing you a fortune if you have to re-do it all or pay someone else to!

Also what is SBR? and WBP

SBR = Styro Butane Rubber – used as a primer it acts as a waterproofing agent.
WBP = water & boil proof – it's an exterior grade ply & the adhesive used to stick the plywood veneers together is water & boil proof (as opposed to standard ply which isn't); this prevents the risk of water in the tile adhesive de-laminating the ply & prevent de-lamination if moisture/damp gets in from underneath; the underside & edges should still be primed with SBR.