The most popular sizes for slates are 600x300mm and 500x250mm, and at Coast to Coast Roofing we grade all of our slates to thicknesses which give the roof a flatter, more traditional look. This helps us when roofing around a chimney or when repairing a roof.
The advantages of natural slate roofing are that it has a proven method of application and fixing, it is light but durable (Welsh slate is estimated to last 150 years), and that it is non-porous so allows a faster flow of water.