Exterior Slate in Freeze-Thaw Climates: Natural vs. Synthetic

Northern Arizona’s cold winters and snow make natural slate risky—water enters fissures, freezes, and spalls the stone. Synthetic (composite) slate offers a durable, lighter alternative.

Why Synthetic Slate Works

• Freeze-thaw proof – No layered cleavage to trap water.
• Uniform thickness – Faster, easier installation.
• Recycled content – Often rubber/plastic composite; some qualify for LEED points.
• Colorfast – UV-stabilized pigments resist fading.

Reputable Brands & Resources

• DaVinci Roofscapes – Kansas-based, widely distributed.
• The Money Pit guide – Pros/cons, installation basics.
• Old House Web – Detailed comparison.

If You Insist on Natural Slate

Choose dense, low-absorption slate (ASTM C629 “S1” rating). Install over a waterproof membrane with stainless-steel fasteners. Seal with a penetrating silane/siloxane sealer. Expect higher cost and maintenance.

For a commercial build, synthetic slate’s warranty (often 50 yr) and lower installed cost make it the pragmatic choice.