Grades Of Roofing Slate

Slate from cupa 5 and 18 quarries have more of a textured finish.

Grades of roofing slate.

S 1 will provide a service life of over 75 years s 2 will provide a service life of 40 75 years. 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. Greenstone slate is measured by eye to thickness and is then split by hand.

N is cupa s natural selection. 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. According to astm test c 406 roofing slate falls into three grades of classifications.

Grade s2 slate s service life is 40 to 75 years. Grade s3 slate has an expected service life of only 20 to 40 years. A standard grade slate cupa h selection will be less uniform and will require more sorting prior to use. Welsh slate still comes in 3 grades referred to as capital 5 5mm thick county 7 mm thick and celtic 9 mm thick.

Roofing slates are rated through the american standards of testing and materials and given a slate classification from s 1 to s 3.