Grades Of Roofing Slate

According to astm test c 406 roofing slate falls into three grades of classifications.

Grades of roofing slate.

Welsh slate being very flat and smooth as well as a nominal 5mm thickness. It is truly the result of a craftsmen s. Grade s3 slate has an expected service life of only 20 to 40 years. But the finished project will look as good if due care is taken of the slate grading.

A standard grade slate cupa h selection will be less uniform and will require more sorting prior to use. Grade s2 slate s service life is 40 to 75 years. Standard grade rough texture. Slate grades are intended as a prediction of the slates expected service life.

This further highlights the traditional regional variations. Slate from cupa 5 and 18 quarries have more of a textured finish. Welsh slate still comes in 3 grades referred to as capital 5 5mm thick county 7 mm thick and celtic 9 mm thick. N is cupa s natural selection.

Greenstone slate is measured by eye to thickness and is then split by hand.