Freeze-Thaw and Slate: What Builders Need to Know

Freeze-thaw cycling is the silent killer of building materials in cold climates. Here is how natural slate handles it.

The Science

Water expands 9% when freezing. Porous materials crack from the inside. Slate with water absorption under 0.4% has almost no water to freeze.

Test Standards

EN 12326-2 specifies 150 freeze-thaw cycles for roofing slate. Our slate passes without visible damage.

What to Specify

For Minnesota winters, Canadian projects, or alpine regions, request freeze-thaw test reports and choose high-density slate (2.75 g/cm3 minimum).