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Our mid 60’s solid floor has broken up were the carpet gripper has been fitted, and I need to repair it without causing any damp issues.

The floor consists of a thin tile on top of a black layer (15mm) of something ? On top of concrete. I was thinking of coating the old stuff with SBR, then bringing back to level with a strong sharp sand mix, then painting on a liquid DPM ?

There is also a 5mm gap between the floor and the wall. Can I mortar this up as well to prevent drafts, or is it an expansion gap ? So maybe use either foam or a urethane sealant ?

Thanks for your help

Hi monty2468,
On top of the concrete you have a layer of bitumen/tarmac which is your DPM. Nailing into this has broken it up - its rather like a layer of toffee on a tray. You may do better to start with painting on numerous layers of bituminous DPM before you try building up the levels. Try using expanding foam to seal the edge gap, if this acts as a wick for damp you will have to identify whether the damp is coming from the floor slab or walls.
Regards S