Thanks
@cdbe. Really appreciate it. So it would be a case of adding some SBR to the mortar mix suggested above and using that to replace what's there/adding to steps? Or is there a different ratio you'd recommend?
Do you still reckon it's worth adding something afterwards too for additional waterproofing?
Also Is there any particular SBR you'd recommend and what ratio would you suggest?
Appreciate this will all potentially be a sticking plaster, but if I can make it semi usable for a couple of years whilst we figure out what to do with it, I'd be happy.
Cheers.