I'm a jobbing builder doing the ccasional basic tiling job , but I could do with some advice on this one. While planning to carry out some chimney pointing and flaunching around the pots, it was soon apparent the stack was in a dangerous condition so I dismantled it and plan to rebuild with concrete blockwork instead of the copying the original stone. The customer isn't keen on render finish so I've proposed cladding with sandstone tiles, but can only find product which is 22-25mm thick instead of 10-15mm which I hoped to source. Can anyone reccommend a suitable adhesive to bond sandstone to concrete? Will the surfaces require priming? Any suggestions of natural sandstone tiles suppliers? Cementitious or Epoxy for failsafe bond? I'd be grateful for your comments.