Some Advice For Tiling Kitchen

[Swindiff]

2 month wait is ok. Just want to check that this floor construction is adequate

Concrete base - 25mm Celotex - 50mm screed with fibres

Should there be a plastic sheet separating the Celotex and screed, or does the screed just go straight onto the Celotex, does it need to be prepped in any way?

 

[Swindiff]

I'd like to throw something else into the mix now, underfloor electric heating 🙂

I guess this would go on top of the screed and tiled directly onto?

 

[Tile Shop]

I'd be looking at lifting floating floor and either getting it screeded to desired height, or fitting marmox boards, available from 6-60mm, to concrete base.
Most cost effective is screeding for sure but you'll then have to wait for at least two months before its dry enough to tile on.
Marmox boards can be tiled on straight away..

I'd like to throw something else into the mix now, underfloor electric heating 🙂

I guess this would go on top of the screed and tiled directly onto?

BAL Quickset cement can be added in place of normal cement if you wanna fast-track it. Going onto a polythene layer then Celotex to build up the level, would mean the heat transferring down 65mm of screed (minimum thickness of screed on a floating layer) before bouncing off the insulation so it will use extra power on the initial heat up.

So my opinion would be, Polythene layer, 65mm cement/sand screed (1:4 mix), 10mm Marmox, UFH, SLC, Flexy adhesive, tile, grout, finish!

But there are guys on here with more experience than me, that may blow my theory out the water and have a more suitable suggestion 🙂

 

[J Sid]

I'd like to throw something else into the mix now, underfloor electric heating 🙂

I guess this would go on top of the screed and tiled directly onto?

underfloor heating in the screed

 

[Swindiff]

Either in the screed or on top, open to opinions. Is there a need for a SLC if on top of the screed, I can see how it would probably make laying the tiles easier.

If I screed first then put insulation on top, rather than the other way round, would it be better to have a thinner screed, say 50mm and a thicker insulation layer, 25mm as doing it this way the screed is laid directly onto the concrete, not on insulation.

 

[Tile Shop]

The SLC is to go over the electric heating cables, not the screed (unless its really wonky). It a) protects the cables while tiling, b) encases the cables to get full heat transfer, c) gives you a perfectly flat surface to tile onto and d) easier to lift the tiles if you fudge up or have to replace any in the future........ This will differ if you use a system like Ditra Heat as they recommend tiling it directly without SLC providing you hit 100% coverage. But double check with the heating manufacturer for their recommendations.

If its a new screed it should be pretty level to begin with. Any minor imperfections can be overcome with adhesive when laying the insulation boards (as an example, Tilemaster Rapid Setaflex can overcome 12mm) , but again ensuring you have a 100% solid bed and no voids. If your floor is out by more than what it says on your bag about maximum depth, then yes you will need to level it first, before laying your insulation. Or you could consider switching to a PTB adhesive.

 

[Swindiff]

OK so thinking as I will be getting a new screed laid, an in screed system will probably work out a lot cheaper. I have about 75-80mm to play with. So 25mm of Celotex laid on the concrete subfloor. Heating cable attached to the Celotex. I have found this kit online which seems reasonable.
In-screed Underfloor Heating System
Screed with a 50mm thick fibre screed. Tile directly onto the screed. Would this be a legitimate method?
Does the Celotex need fixing in any way to the concrete subfloor?

 

[J Sid]

water fed in screed heating not electric

 

[Swindiff]

I have ruled water fed out, the electric will be much easier and cheaper to install.

 

[J Sid]

but not to run 🙁