Tiling a concrete hearth

[Muggles12]

Hi.

I’m planning to tile over an existing concrete hearth which is uneven and will need levelling but only up to around 10-15mm. I’d like the hearth to be level with the start of the floorboards to allow for tiling.

I also have engineered floorboards butting up to the hearth which I plan to have as a flush transition to the tiles with a brass L trim to separate them.

My issue is:

1) that I’m unsure what to use to level the hearth. I’ve read Sharp sand and cement mix in 4:1. Is this best? Or should I try to use a floor levelling compound?

2) should I leave an expansion gap between floorboards and brass trim? There are expansion gaps on every other wall of the room.

I’ve attached some photos of the current situation.

I also have a cementitious tile backer which I could use as a base for tiling.

Would a sand cement mix be okay, followed by the tile backer which I know would provide a flat surface?

Thanks

 

[RandomGrinch]

Hi,

I'm only a DIY'er so feel free to ignore!
You may also have finished the job by the time you have seen this reply!

Anyway, I think sorting the hearth for the tiles is the easy part!
I would lay a membrane; you wouldn't want moisture from below the hearth to come up and spoil the new floor.
Then lay some ready mixed mortar, i.e. :

https://www.screwfix.com/p/cementone-general-purpose-mortar-grey-5kg/36857

And place the cement board on top, for a perfect surface to tile onto.

Having a flush transition between the tiles and floor, may be an issue though.

Some guidance on the regs here:
https://www.hetas.co.uk/hearth-boundaries/

It is usual for the hearth zone to be demarcated, by raising it above the floor level. This doesn't have to be the case, but I'm not sure that a brass trim piece may be enough?

There is also the expansion gap problem. Expanding foam tape is very useful to fill the gap, but could you use the brass trim to cover this?

 

[tell80]

For now dont do any more work until you've done whats suggested below.
Remove all the hearth infill surface mortar to show whats happening below, then pic on here.
Some kind of plastic can be seen at the edges but you cant rely on that as a DPM.
You dont need any damp creeping up or any wood tobrickor earth contact.

Have you been under the floor and had a look around the hearth fender walls and joists?