What is S-1? What is Miami-Dade County approved?


The American Society of Testing on material has established a standard specification for roofing slate, C-406, which tests the slate for three physical requirements that the slate must pass to be classified as S-1 Slate.

• C -120- Modulus of Rupture of Slate
• C- 121- Water absorption of Slate
• C – 217- Weather resistance of Slate

All of our slate at The Virginia Slate Company has been tested and retested over the years and qualifies as S-1 slate. In addition, all of our slate is Miami-Dade County approved. In order to have your product “Miami-Dade-County “ approved the product must pass many stringent tests including the wind up-lift test where the slate is tested on a roof and subject to 110 mph wind with gust up to 140 mph. This test is by far the most severe test for any roofing product to pass. If your product fails any one of the tests, the product can not be “Miami-Dade-County Approved”.