Tiling on concrete floor

[Esseesse]

Hi everyone, I have a conservatory with a horrid green thin felt-like carpet and underlay on the floor. Underneath is nice flat concrete as far as I can tell from pulling up the corner.

I'm intending to tile it with some terracotta/quarry tiles. Do I need to do anything first or can I tile straight on to the concrete? I have done some tiling successfully before, but only walls onto a surface that I had just removed old tiles from.

Thanks!

[its hot]

as long as its level just straight on plan the tiles first dont start at one edge ideally get a centre line from all sides and work out to the edges

[toohuge]

You'll be fine tiling straight on....

Don't be tempted to add too much water to your mud, keep it nice and thick. I have found it easier to tile this way and use the mud to correct any inconsistencies on the concrete.

[Pheo]

You might want to think about insulating the slab a little, otherwise that floor is going to be quite cold. Ours is!

[Salesy]

Or even add electric underfloor heating.

[loughran]

Aye, I just installed Warmup loose wire underfloor heating under tiles in the shower room and toilet. Easy to do, not too expensive and very effective. And you don't have to use it if you're feeling tight but you can if you're feeling nippy.

[B17NNS]

As above, fine to tile straight onto it. If you're going to add electric underfloor heating you'll need to use flexible adhesive and grout.

[m4ckg]

I'd be tempted to prime it first

[blade7]

Or put hardener on it.

[Esseesse]

Thanks for the replies, and yes I can see that keeping the mud thick to even out inconsistencies makes sense. I did similar on some of the kitchen walls I did.

Why prime it/put hardener on it?

Are there any options for thin insulation of the slab? The underfloor heating is a nice idea, but I'm inclined to keep it simple and for people to wear slippers if they can't cope.

[Esseesse]

I've read about thin (but expensive) 'aerogel' insulation. Any good for this purpose?

[toohuge]

Where is this floor? I.e. is it just a slab, with nothing underneath it?

You may not want to grout all the way around the edge of the floor that you lay. I have seen a few problems with the building settling and tiles popping up, which isn't ideal. To avoid this, man tilers simply use silicone on the the edges to allow for expansion / movement.

[voicey]

I stuck down 10mm XPS insulation onto our slab with a cement based tile adhesive. Once that had gone off I then stuck the tiles down to the XPS with the same adhesive. Dead easy and the tiles are lovely to walk on.

[stanwan]

Consider using an insulated tile backer board and then laying some UFH matting on top -It'll improve response and heat retention. AS an alternative to silicone, consider schluter maintenance free perimeter profiles...

[Esseesse]

Thanks for the tips on the edging, I hadn't thought of the slab moving slightly vs the walls. As far as I know it's just a slab with nothing underneath it. It's the floor of the conservatory in the house I've moved to recently. It's probably about 10 years old, and a reasonably nice conservatory (hard wood), although it has a plastic roof rather than glass.

What's the difference between insulated tile backer and XPS insulation? These do seem like a good idea, and 10mm should be easy enough to deal with.

[monthefish]

stanwan said:

Consider using an insulated tile backer board and then laying some UFH matting on top -It'll improve response and heat retention.

False economy not to insulate first (if you've got the space/depth - The insul boards are about 20mm thick from memory)

[m4ckg]

Esseesse said:

Thanks for the replies, and yes I can see that keeping the mud thick to even out inconsistencies makes sense. I did similar on some of the kitchen walls I did.

Why prime it/put hardener on it?

Are there any options for thin insulation of the slab? The underfloor heating is a nice idea, but I'm inclined to keep it simple and for people to wear slippers if they can't cope.

Google primer for concrete floors and you'll get the correct answer. Under no circumstances use pva to prime the floor

[B17NNS]

m4ckg said:

Google primer for concrete floors and you'll get the correct answer. Under no circumstances use pva to prime the floor

Why? You're applying a cement based adhesive onto a cement based floor. It's not a bathroom. A lick of PVA will control the suction and improve the bond. What's the issue with PVA?

By all means use BAL primer or SBR if you're feeling flush but it's really not necessary for this application.

Edited by B17NNS on Thursday 19th March 20:09

[Neil - YVM]

B17NNS said:

m4ckg said:

Google primer for concrete floors and you'll get the correct answer. Under no circumstances use pva to prime the floor

Why? You're applying a cement based adhesive onto a cement based floor. It's not a bathroom. A lick of PVA will control the suction and improve the bond. What's the issue with PVA?

By all means use BAL primer or SBR if you're feeling flush but it's really not necessary for this application.

Edited by B17NNS on Thursday 19th March 20:09

Seriously PVA has no place whilst tiling.

PVA forms a skin, and prevents the adhesive bonding to the surface as the manufacturer intended.

Hence the use of PVA will render the guarantee void, from all the leading adhesive manufacturers , ie Bal, Ardex, Granfix, Nicobond.
I have to guarantee our work, so would never do anything but follow the manufacturers instructions.

[m4ckg]

B17NNS said:

Why? You're applying a cement based adhesive onto a cement based floor. It's not a bathroom. A lick of PVA will control the suction and improve the bond. What's the issue with PVA?

By all means use BAL primer or SBR if you're feeling flush but it's really not necessary for this application.

Edited by B17NNS on Thursday 19th March 20:09

I'm not a tiler myself but the contractors I use work to high standards so I'll always take their advice.

Taken from a tilers forum:

DO NOT use standard PVA on any tile base, it remains water soluble & will reactivate if it gets wet; use an acrylic/SBR tile primer/bonding coat.

I