Hi all - first time poster here.
We have a slab floor in early 18th century property's living room, assumed to be concrete but could be limecrete. Around the perimeter of the floor / framing the slab is about 100cm of ~20cm x 20cm stone tiling (photo).
Some limited damp problems on one of the walls - where the tiling meets the slab - and certainly not helped by the rubber-backed carpet we've just removed.
So...we have 22mm thick large format (some up to 900mm x 600mm) limestone tiles that need fixing.
Question - how best to do this? Given we're unsure what exactly the slab is made of, we'd prefer to err on the side of caution / breathability and use NHL - considering height restrictions, would a 5-6mm bed of NHL5 be enough? (grouting with NHL2). If not, are there height-saving / breathable alternatives?
Thanks very much

We have a slab floor in early 18th century property's living room, assumed to be concrete but could be limecrete. Around the perimeter of the floor / framing the slab is about 100cm of ~20cm x 20cm stone tiling (photo).
Some limited damp problems on one of the walls - where the tiling meets the slab - and certainly not helped by the rubber-backed carpet we've just removed.
So...we have 22mm thick large format (some up to 900mm x 600mm) limestone tiles that need fixing.
Question - how best to do this? Given we're unsure what exactly the slab is made of, we'd prefer to err on the side of caution / breathability and use NHL - considering height restrictions, would a 5-6mm bed of NHL5 be enough? (grouting with NHL2). If not, are there height-saving / breathable alternatives?
Thanks very much
