How Indiana's Freeze-Thaw Winters Affect Your Foundation

Water that's worked its way into a crack, even a hairline one, expands as it freezes. That expansion pushes outward against the crack walls with real force, widening it slightly. When temperatures rise again, the ice melts, water fills the now-slightly-wider crack, and the cycle repeats on the next freeze. Indiana's winters are known for exactly this kind of back-and-forth temperature swing rather than a single sustained freeze, which means a lot of repetitions in one season.

A hairline crack that isn't a structural concern on its own becomes more of one if it's letting water in every winter. Each freeze-thaw cycle it goes through makes it slightly wider and lets slightly more water in next time, which is a slow but real progression if a crack goes unsealed for multiple winters in a row.

Sealing a crack before winter, rather than after, keeps water from getting into it in the first place, which sidesteps the freeze-thaw expansion problem entirely. For a crack that's already been through a winter or two, an inspection can tell you whether it's still just cosmetic or whether repeated freeze-thaw cycling has moved it into structural territory.