About three years ago, a local builder put some slabs of sawn sandstone along the top of a garden wall for me. At one end, where the wall slopes down at about 20deg, the last slab (about 1m x 0.5m x 40mm) has come loose. Some day soon, it's just going to slide off, I should think, especially now the weather can get under it. Can anyone suggest a method I could use to put it back and secure it there for myself, or should I just give in and have the builder back for another shot at it? Would it do any good to acquire a fairly large quantity of some sort of adhesive, or is that a stupid idea?
Thanks for any hints,