Tiling over tiles using cement board

[Rhys Allison]

Hi All,

We’re going to be re-tiling our kitchen floor, it’s a concrete slab with porcelain tiles as exising.

I have some Marmox board left over from the bathroom and intend to use it on the floor as we’re having underfloor heating and the floor is currently cold under foot.

What’s the best method to fix Marmox to tiles?

Would it be best to hack up the existing tiles and Marmox the floor? Or to screws over and Marmox over the screed?
Thanks
Rhys

 

[Bond]

I would take up the existing tiles, perhaps level with slc , and fix boards with fast flex adhesive then scrim tape joints. May need to weight boards something like the above.

 

[Flintstone]

Take up tiles, level the floor if it's bad, If not just stick the marmox boards down with any S1 adhesive. If there's some adhesive residue, step up the trowel size. Fit your underfloor heating then level the whole floor prior to tiling. Not a straight forward diy job I must say.

 

[Rhys Allison]

Thanks for the replies.

My preferred method would be to go directly over the top, the existing tiles are level and there’s no broken tiles.

I have some C2F adhesive which Marmox recommend for concrete slabs, would this suffice?

 

[Time's Ran Out]

I could start a Poll to get the best method for you but not sure you’d ‘prefer’ the answer!
So far it would be 3-0 in favour of taking the tiles up.

 

[Qwerty]

Take them up



4-0 😀

 

[Waluigi]

Why go to the expense of a proper installation (insulation boards and UFH) yet base it on the unknown bond between your existing tiles and the substrate? Not worth the risk IMO

 

[WetSaw]

What about the level going into the other rooms? Insulation board, heating and then tiles on top is going to give you quite a difference.

 

[Flintstone]

Usually between 25 and 30mm build up

 

[J Sid]

take them up, an hours work, if that...

 

[Boggs]

Up.

 

[Time's Ran Out]

8-0

 

[Andy Allen]

Leave them down. !
















Not really.....take them up...9-0

 

[Rhys Allison]

Right they’re getting taken up!

It’s an old Victorian property so the existing concrete base wont be level.

Any suggestions for the self levelling screed / compound?

 

[Waluigi]

Wouldn’t it be 9-1.......just sayin’ 😉 😀

 

[Dumbo]

I would take them up . Skim over with levelling comp stick down boards . Lay ufh level over then tile .
As @Localtiler says you are looking at a extra height build up of 25 to 30 mm on top of your existing tiles so probably 40 mm off of the screed.