What is a Frost Line?

Full definition

The frost line is the maximum depth at which ground soil freezes during winter in a given region. For most of the KC metro, the frost line is 36 inches per the 2018 International Residential Code (locally adopted). The frost line determines minimum burial depth for water lines, footings, and any buried drainage that needs to stay flowing year-round.

Buried downspout extensions in KC don't need to be buried below the frost line because they're not pressurized water lines, but they should slope at 1/8 inch per foot minimum to prevent water from freezing in the line.

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