Why Important
What to look for
The slates are characteristic, being very thin, smooth surfaced, generally a purplish colour and regular sized, leading to uniform courses.
When to look
How to fix
Because the slates are much larger, they are double nailed in the middle of each slate which means slates cannot be swung aside, making them more difficult to patch.
Avoiding creating problems
Ensure that any new or replacement slate is the same thickness and size as the one being replaced, to avoid creating differences that alter flows of water.
Historical background
Welsh slate was easy to source in Birkenhead, and therefore cheep and easy to obtain. Later in the 19th Century, Welsh slates (supplied by train) started to be used in Edinburgh.