Limestone tiles on a limecrete floor - advice on breathable adhesives and membranes please

[grsebs]

Hi all,

We've installed a breathable limecrete floor with wet UFH in order to manage problems with damp in the solid stone walls of our cottage (which is also being repointed with lime). We're planning on finishing the floor with limestone tiles. Does anyone have any thoughts or advice on the following:
1) would it be worth putting a levelling compound down first or just tile direct on to the screed (it's reasonably flat already) using a suitable primer?
2) same question regarding a decoupling membrane - and if so, can anyone recommend a breathable membrane?
3) sand & lime or a specialist adhesive? Breathability is key, so if the latter it would need to be a breathable adhesive - suggestions?

Many thanks!

 

[Dave]

Hi.
Kerakol make adhesives suitable for limecrete floors. Ditra mat is a good vapour equalisation membrane but check with kerakol and schluter uk on compatibility.

 

[Jon_Hall]

Hi, I have worked on a few of these screeds, and this is how we tiled them.
Firstly we scraped, brushed and vacuumed the screed. Then primed it with one coat of Primebond at a ratio of 1 part primer to 4 parts water.
We then decoupled the floor using Rapid Porcelain Grey adhesive and Permalayer anti fracture membrane. Then tiled using S1 Rapid Porcelain & Stone White adhesive and grouted with 4 into 1 grout.
All of the products are breathable including the Permalayer.
The only issue you may have, is if damp rises through the screed you may get some efflorescence come through the grout joints and possibly the stone.

 

[Rae]

If its limestone you need ditra matt ,

 

[Ajax123]

If its limestone you need ditra matt ,

Not necessarily. Depends on the limestone as the coeffiicient of thermal linear expansion for the screed and the stone will be very similar and lime screeds tend to be more flexible and less prone to cracking.

Id recomend a conversation with Kerakol as they do a lot of clever stuff for breathable floors.

 

[Jon_Hall]

I agree with Rae, its also in the Stone Federations guidelines to decouple when installing natural stone over UFH.

 

[grsebs]

Thanks all for your thoughts. The Kerakol and Norcross products both look worth considering and I've also come across Seciltek Adhere which looks like it might also do the job.

For info, I've been in touch with Schluter and they've responded to say that the Ditra matting isn't breathable and therefore not suitable for use over limecrete.

 

[Rae]

Not necessarily. Depends on the limestone as the coeffiicient of thermal linear expansion for the screed and the stone will be very similar and lime screeds tend to be more flexible and less prone to cracking.

Id recomend a conversation with Kerakol as they do a lot of clever stuff for breathable floors.

See