Some months back I asked about suitable ways of doing this, and received lots of helpful replies and advice. I've now acquired some reclaimed Welsh roofing slates which I plan to use to make the three-course block wall in my garden look a bit less industrial. I don't want to hang them overlapping, as on a roof, but simply flat onto the blocks, brick-like.
I'd welcome suggestions as to the best method of fixing them. A bed of mortar? One of the weatherproof gun-glues? Waterproof tile adhesive? Nailed to battens screwed to the blocks? Another way I haven't thought of?
Many thanks.