How long does a mansard slate roof last?

When installed properly using copper fasteners and ASTM S-1 roofing slate, a mansard slate roof will last well over 75 years. The Cabanne House located in Forest Park (St. Louis, MO) was completed in 1876. The Second Empire style house, most easily recognized by its distinctive mansard slate roof, was a popular style throughout St. Louis following the Civil War.  Our North Country Unfading Black roofing slate was selected for the re-roof.

At North Country Slate, we warranty all of our roofing slate products for a period of 75 years. This confidence in our product’s longevity is not based on accelerated weathering tests in labs or estimates of how long a material will last. It is based on the proven performance over the last thousand years.

In order to ensure we are supplying the best slate available, samples undergo three tests required under ASTM C406 are C121 Water Absorption of Slate, C217 Weather Resistance of Slate, and C120 Flexure Testing of Structural and Roofing Slate. Based on the results of these tests, roofing slate is graded as S-1 (over 75 years) S-2 (40 to 75 years), or S-3 (20 to 40 years). Our company does not distribute lower quality S-2 or S-3 roofing slates to the market.

When it comes to selecting a product for a re-roof you should know what the original color was, size and thickness of slate, are the slates single size or random width? Are there any special trimmed slates like the ones installed on the Cabanne House.

Hiring a skilled slater is also important as they have the knowledge to ensure the slates are good quality and the training to make sure the slate roof lasts another 75 + years.

In addition to the slate roof, the Cabanne House also has a lot of copper details; flat lock soldered copper, standing seam copper and copper hips.  The combination of the slate roof and the copper details provide for a low maintenance roof.

At North Country Slate, we are a proud supplier of North American produced roofing slate.