09/09/2026
New in the line: Vermont Gray-Black, available exclusively in SLATE2.
ASTM C406 S1 grade. 1/4" to 3/8". 550 lbs per square.
That last number is the one that matters. Comparable full-weight Vermont slate runs 960 lbs per square. At 43% less load, the structural reinforcement conversation usually ends before it starts, which, in adaptive reuse and historic work, is often the difference between specifying slate and specifying something that imitates it.
(Read full details here: https://www.californiaslatecompany.com/post/vermont-gray-black-lightweight-vermont-slate)
Appearance is uniform medium-to-dark gray with subtle black linear markings. We will also tell you what most suppliers will not: roughly 4-6% of these slates show slight weathering after 12 to 18 months. It reads as character; it is predictable, and you should know it before you put it in a spec rather than after.
Material service life 100-200 years. 50-year system warranty.
https://www.californiaslatecompany.com/slate2
