I have a very small amount of slate roofing to do and I was very pleased to come across a website that contains some great data-sheets on how to go about roofing with slates >>
In their own words: “Welsh//Slate based in North Wales is the worlds leading manufacturer of high quality roofing slate, architectural and aggregate slate products. Welsh//Slate roofing products have an unparalleled reputation for durability and quality.”
The link will take you to the sites Design & Installation (Technical) page from where you can find plenty of related and well laid out data-sheets.
Informative and Welsh… what more could you want?