Why St. Joseph Deck Footings Have to Go a Full 36 Inches Deep

Water in the soil around a footing expands when it freezes, and St. Joseph's building code sets the local frost line at a full 36 inches to account for that cycling — deeper than the requirement in several other parts of Missouri. It's exactly why so many of the deck repairs we get called out for around Buchanan County trace back to the footing rather than the boards themselves. A deck built to a shallower frost spec elsewhere isn't automatically safe to replicate here — frost depth is set locally, not statewide.