How much does a slate roof weigh?

Posted By On 6 Feb 2019

How much does slate weigh?  That’s a great question, especially when you are comparing it against other roofing products.  Roofing slate created by nature over 500 million years ago has been used as a roof covering for more than a thousand years!

Back in 1926, the commercial standard slate thickness was 3/16”. In the 1950’s the ASTM changed slate’s nominal thickness to 3/16” – ¼”. Today, the standard thickness of slate is ¼” – 3/8”.  A slate’s thickness depends on the quarry’s stone characteristics which can change from bed to bed. The North Country Unfading Black natural roofing slate can be split consistent 3/16”, ¼” or 3/8” depending on the slate specification.





3/16” 675-700 LBS
3/16” – ¼” 820 LBS
¼” 935 LBS
¼” – 3/8” 1170 LBS
3/8” 1405 LBS
½” 1870 LBS

When ordering a slate’s thickness, considering the weight should be top priority.  Not only for the building’s structural integrity, but shipping costs, labour/installation costs and lead-times will play a big factor.  Some markets, such as California and Texas, prefer a lighter weight slate roof.  While some of the more traditional slate markets such as Illinois, New York, Pennsylvania and Massachusetts prefer a heavier 3/8” slate product.

In the Fall of 2018, we supplied 122 squares of our North Country Unfading Black slate (16”L x 8”W x 3/16”) for the First United Methodist of Oak Park’s reroof. The original church was destroyed by fire in 1916 when lightning struck the church. The church was rebuilt in 1918 with stones salvaged from old building. The original slate roof was likely an old Pennsylvania black slate roof which was split to 3/16” back in 1916.  Our North Country Unfading Black slate was a great match in color, texture and thickness.  Current ASTM test results were submitted and the results indicated all test methods meet the S1 classification as per ASTM C406 providing a service life of 75 + years.

Some of our 3/16” light weight slate projects include; Golden Gate Park Murphy’s Windmill in San Francisco, CA; University of Illinois’ Farm House Fraternity; Perth County Courthouse in Stratford, ON; Grace Anglican Church in Milton, ON and St. Anne’s Anglican Church in Toronto, ON.

For more information on slate coverage and weights and how much a pallet of slate weighs, please call our office at Toll Free 1-800-975-2835.

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