Frost Depth & Snow Load
Locally adopted frost line depth, footing depth, snow load, and the rest of the building design criteria your city enforces.
Two numbers precede every foundation and roof: frost depth, which sets how deep footings go so freezing ground cannot heave them, and ground snow load, which drives the structural math above. Both are adopted locally in the building code's climatic design table, and both derive from state maps and national standards.
Ground snow load is the mapped input; roof snow load is the calculated result; drifting and elevation create case-study zones where the map is overridden. The adopted local table, not a generic map, is the citable authority.
All 50 States: Frost Depth & Snow Load at the State Level
Each tile shows the strongest state-level rule for that state. Click a state to see its full statewide rules and how local cities are constrained.
Severity: Few Restrictions · Light Restrictions · Some Restrictions · Significant Restrictions · Heavy Restrictions
What's Covered
Frost Line Depth
How deep footings must go below finished grade to sit under the frost line, as adopted locally in IRC Table R301.2 or an amendment to R403.1.4.
Ground Snow Load
The ground snow load in pounds per square foot (Pg) the jurisdiction adopted, which sets what roofs and structures must be designed to carry.
Roof Snow Load
The minimum roof or flat-roof design snow load (Pf), a different quantity from ground snow load, where the jurisdiction adopts its own figure.
Deck Footing Depth
How deep deck and porch footings must be set, plus the size, attachment and permit thresholds that apply to decks specifically.
Frost-Protected Shallow Foundations
Whether the jurisdiction permits a frost-protected shallow foundation under IRC R403.3 instead of digging to the full frost depth, and on what terms.
Building Design Criteria
The full set of local design criteria, wind speed, seismic design category, weathering, termite risk and ice-barrier requirements, as adopted.