I am constructing a new hearth for my wood burner. Can I lay the clay tiles directly into/onto my lime/sand/cement mortar I am using for the slab or do I need to use a tile adhesive? The reason that I am asking is that the tiles are reclaimed hand thrown and far from flat on the rear. The tile adhesive would have to vary greatly for each tile and across each tile. They are 230mm square and approx 18mm thick.
Many thanks.
Many thanks.