Grades Of Roofing Slate

This further highlights the traditional regional variations.

Grades of roofing slate.

Greenstone slate is measured by eye to thickness and is then split by hand. Standard grade rough texture. Slate grades are intended as a prediction of the slates expected service life. Grade s1 slate has an expected service life of more than 75 years.

But the finished project will look as good if due care is taken of the slate grading. Welsh slate still comes in 3 grades referred to as capital 5 5mm thick county 7 mm thick and celtic 9 mm thick. A standard grade slate cupa h selection will be less uniform and will require more sorting prior to use. Welsh slate being very flat and smooth as well as a nominal 5mm thickness.

Grade s3 slate has an expected service life of only 20 to 40 years. It is truly the result of a craftsmen s. According to astm test c 406 roofing slate falls into three grades of classifications. Roofing slates are rated through the american standards of testing and materials and given a slate classification from s 1 to s 3.

Grade s2 slate s service life is 40 to 75 years.