Waterproofing over concrete slabs

[sunspot]

Many houses here seem to have salts emerging through the grout lines on their ground floors.
Water is clearly leeching through.

Would it help to put a cementitious or bitumen layer on top of the concrete slab?

We are also going to waterproof the perimeter of our house, where it meets terraces or soil.

Appreciate any views. We'd like to avoid the damp problems that seem to plague so many houses here. We are in Kamares.

[Uncle D]

Does the damp only occur in winter or are you experiencing it now also?

[sunspot]

Seems to be a long-term build up of salts on grout lines, perhaps over several years.

[Uncle D]

We get Damp coming up through the tile grout in one room but only when there is heavy rains in winter.
In another property that we had it was also doing it in the summer and it turned out to be a leaking water pipe under the floor.
if you try to seal the tiles the pressure may build up and begin to lift the tiles from the floor.