Hello people. I am intending to lay a natural stone slab over the top of a grey council slab. The slabs are unlevel but i can sort that out with the mortar base. Can i do this and is it best to spot the new slabs with the mortar or use a full mortar base considering the sub base? In the past i have used a fairly dry mix for laying slabs but have recently been told to use a wet mix for laying slabs. The new slabs are between 18mm and 34mm thick and i have about 7.5 inches to the damp course. Any advice/help would be appreciated .