Tiling to plaster board and concrete

[John Smith Esq.]

Hello,

We are tiling floor and walls using 300 x 600 (9mm thick) tiles. The floors are bare concrete and the walls are 12.5mm plasterboard with a paper covering.

I'd be grateful for advice:

A) do we need to use primer on the floors and walls? If so, which type? Gaps between plasterboard have been covered with scrim tape so far.

B) which tile adhesive would you recommend for the task, bearing in mind the previous question?

C) what is the minimum and maximum thickness of adhesive? Because of an uneven concrete base, we could ideally do with going as thin as 3mm and up to 15mm to ensure an even surface. Could go above 3mm if absolutely necessary.

Many thanks
John

 

[accelerator]

Let's Go!

 

[accelerator]

C) what is the minimum and maximum thickness of adhesive? Because of an uneven concrete base, we could ideally do with going as thin as 3mm and up to 15mm to ensure an even surface. Could go above 3mm if absolutely necessary.

Use self-levelling compound.

 

[John Smith Esq.]

Use self-levelling compound.

Prefer to just use tile adhesive.

 

[simplesteve]

A) SBR. Get it from the tile shop when you are in getting your
B) Cementuous tile adhesive. I.e. powdered stuff in a bag. Would suggest a standard ( slow set) setting one, as a Rapid Set would stress you out !
If you intend using white grout, then a white adhesive will also keep stress levels down.....
C) A minimum of an 8 mm notch trowel. Personally I prefer using a 12.
There's now way you can do down to 3 - you'll need to rethink your floor prep.....

 

[robinbanks]

There's now way you can do down to 3

That's a 6mm notch. Not impossible but id soak the tile and the floor first to make sure it isn't going to suck the moisture out of the adhesive quickly and make working it difficult

Agree with the earlier comment about prep, either SLC or a skin of adhesive on the worst lows and assess level with a straightedge. You don't notice minor mm deviations when walking on a floor so long as the change isn't too rapid

Don't do rapid set in these temps as a newbie. Mapei adhesives come in various flavours and in stock at all the big sheds. Their colour matched grouts and silicones are good gear too. Consider using a mortar gun to apply grout. If grouting in high temperatures keep on top of cleaning grout up as you go

Buy a tile levelling system. If using the wedge kind eg the no nonsense one from Screfix, do not remove the wedges before you knock the spacer sideways (along the grout lines) after the adhesive has set, as the wedge is vital for getting a clean snap of the spacer legs

Do not walk on tiles you have recently laid

Plan your layout before you start; ensure that your tile spacing means between half and three quarters of a tile is at an edge. Nothing looks worse than having a 10mm sliver of tile down one (or both) edges of a room. If you calculate that your tiles will land such that there is less than half a tile's width sliver at any edge, move the entire laying by half a tile's width, which will mean that that tiny sliver before becomes the sliver added into half a tile, which looks much better

If your floor is uneven/ not level fix a level batten to the wall just less than one tile's thickness above the lowest point and tile off that, then when set, remove the batten and fill the gap in

If your tiles aren't rectified consider using larger grout lines to be kind to yourself

If there is a possibility your concrete will crack, use a decoupling membrane to prevent the crack coming through to the tiles

If the tiles are porcelain, buy a decent wet tile saw. You can use a diamond file to improve the finish of cut edges

What will the tiled room be used for? If wetroom, reconsider use of plasterboard and go for aqua panel, jack, no more ply, tile backer or similar backing board that won't degrade if damp

 

[John Smith Esq.]

Thanks for these really helpful responses.

Just to say that the variation in floor level will require adhesive thickness of between 3-4mm and 12mm. We could take the higher parts down a bit - these are near an entrance door so need to think of door clearance and ability to put a mat there in future - hence preference for 3mm. If this is difficult to achieve in practice then we can just grind the floor down a bit.

Can't we just cover the tile in adhesive and then place it down and pat to the level we need? My builder will be using his lazer level throughout to ensure the surface remains level through the entrance and WC where they are being laid.

In terms of the greater depths, as I understand it, Mapei do a flexible grout that can go up to 12mm thick and as thin as 3mm thick. This will mean we can avoid SLC, which has been a pain in the other room and just adds products, processes and complication. For 12mm depths - no problem in principle with just using thicker tile adhesive instead of using SLC? Or are there reasons to avoid this?

The only problem with the Mapei flexible one is that reviews are saying it can take 3 days to properly set... but I agree, better to use slower setting stuff.

Would you definitely apply SBR to the floor and papered plasterboard walls before applying tile adhesive then? We can't just go straight to those surfaces? I see Mapei don't test their products with SBR so we will need to buy a big vessel of their special primer, which will hardly be used (I have a 30 quid tank of it in the shed from two years ago which it seems is now not usable).

 

[simplesteve]

I agree with most of the above, with the exception of soaking the tiles. The floor tiles will definitely be porcelain, and therefore not porous, and don't absorb water. If wet when laid they will not stick to the adhesive. Instead of soaking, I would ' back butter ' the tile, this will ensure a better coverage and uniform adhesion. It will also help with 'sliding' the tiles a bit into place after they're bedded.

 

[simplesteve]

Are you getting you ' adhesive' confused with your ' grout ' ?
( I'm a Bal man myself, I find their grouts much easier to mix and more uniform than Mapeis)

And you 100% need to sbr first. The first thing paper wants to do is suck the water out of your adhesive, and the dusty concrete floor will try the same. Both need to be stabilised first.

 

[John Smith Esq.]

Thanks Steve.

No, not confusing adhesive and grout. When I am talking about thickness of adhesive, I am referring to the need to use different thicknesses on an uneven concrete base to make up the gaps to a level tile surface. As mentioned, we estimate that the deepest area needing to be filled will be 12mm of adhesive between tile and concrete. Can you see any reason not to do this so we can avoid using SLC?

If we go with BAL, can you recommend a variety of theirs that allows us to go up to 12mm thickness and doesn't set quickly? I al intending to use white adhesive as are using light grey grout.

Do you dilute the SBR first?

 

[robinbanks]

Probably a typo:

In terms of the greater depths, as I understand it, Mapei do a flexible grout that can go up to 12mm thick

Sure, fill in the low spots with adhesive first if you want. SLC is easier IMO but if you have excess adhesive..

 

[simplesteve]

Mapei do a flexible grout that can go up to 12mm thick and as thin as 3mm thick. T

this is what confused me
An experienced tiler could cope with that difference in heights, by varying his trowel s as he went along, but I would suggest, as robin does, to just pour some slc. It's easy and straight forward, and it'll make your job soooo much easier.

any Bal ' standard set' adhesive will cope no bother, and as you're going onto concrete you don't need it to be a flexible one.

Yes, sbr needs diluted, usually around 3:1. ( water : sbr) A small bottle would do you.

 

[John Smith Esq.]

Probably a typo:


Sure, fill in the low spots with adhesive first if you want. SLC is easier IMO but if you have excess adhesive..

Ah yes, my fault! Sorry Steve!

 

[John Smith Esq.]

this is what confused me
An experienced tiler could cope with that difference in heights, by varying his trowel s as he went along, but I would suggest, as robin does, to just pour some slc. It's easy and straight forward, and it'll make your job soooo much easier.

any Bal ' standard set' adhesive will cope no bother, and as you're going onto concrete you don't need it to be a flexible one.

Yes, sbr needs diluted, usually around 3:1. ( water : sbr) A small bottle would do you.

We need the adhesive to go on plaster board as well, does this change which adhesive you'd use?

 

[simplesteve]

Nope A good standard set adhesive will do both just fine.
The best tip I would give a first timer is :-
Get your 1800 spirit level, and a dry board marker, and Mark the height of your tiles on it ( 300 in your case) i.e. 6 x stripes You can now put your spirit level on the wall vertically, and move it up and down to get your tile heights in your mind, BEFORE you start tiling. Remember, the 4 heights you have to ' balance out' are: top of bath, bottom of window, top of window, and door frame.
A good tile r will know the size of these cuts before he starts.

Once you know the heights of your lines, do what Robin suggests and screw a baton to the wall and tile up off that, then remove the second day and tile down to the floor. If your floor is really uneven, then I would tile the walls first. ( then the bottom row of tapered cuts don't have to be bang on, as the floor tiles will cover them)

Oh, get yourself a bag of tilers 0-5mm wedges !