Testing frost resistance for cold climates
Freeze and thaw is the quiet destroyer of outdoor stone. How frost resistance is tested, what the results mean, and why northern producers take it so seriously.
By GraniteFirms Editorial
In cold climates, the biggest threat to outdoor stone is water that freezes inside it. Specifying for frost means understanding how stone is tested and what the numbers actually tell you.
How frost testing works
Laboratories subject samples to many repeated freeze and thaw cycles, then check for loss of strength, flaking or surface damage. Stone that comes through with little change is rated frost resistant for the conditions tested.
Water absorption is the early warning
Because freeze damage depends on trapped water, low water absorption is the single best predictor of frost resistance. Dense granites that absorb almost no water tend to pass frost testing comfortably, which is why they dominate northern paving and façades.