Grades Of Roofing Slate

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

Grades of roofing slate.

This further highlights the traditional regional variations. Standard grade rough texture. Welsh slate being very flat and smooth as well as a nominal 5mm thickness. But the finished project will look as good if due care is taken of the slate grading.

It is truly the result of a craftsmen s. N is cupa s natural selection. Slate grades are intended as a prediction of the slates expected service life. Roofing slates are rated through the american standards of testing and materials and given a slate classification from s 1 to s 3.

Welsh slate still comes in 3 grades referred to as capital 5 5mm thick county 7 mm thick and celtic 9 mm thick. Grade s2 slate s service life is 40 to 75 years. Slate from cupa 5 and 18 quarries have more of a textured finish. A standard grade slate cupa h selection will be less uniform and will require more sorting prior to use.

Grade s3 slate has an expected service life of only 20 to 40 years.