Grades Of Roofing Slate

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

Grades of roofing slate. N is cupa s natural selection. Slate from cupa 5 and 18 quarries have more of a textured finish. But the finished project will look as good if due care is taken of the slate grading. S 1 will provide a service life of over 75 years s 2 will provide a service life of 40 75 years.

Grade s3 slate has an expected service life of only 20 to 40 years. It is truly the result of a craftsmen s. Roofing slates are rated through the american standards of testing and materials and given a slate classification from s 1 to s 3. Slate grades are intended as a prediction of the slates expected service life.

Welsh slate still comes in 3 grades referred to as capital 5 5mm thick county 7 mm thick and celtic 9 mm thick. According to astm test c 406 roofing slate falls into three grades of classifications. This further highlights the traditional regional variations. Grade s2 slate s service life is 40 to 75 years.

A standard grade slate cupa h selection will be less uniform and will require more sorting prior to use.