Oklahoma

Statewide summary — confirm with your building department before designing

This audit corrected the seismic design category from A to B. Checked against the USGS ASCE 7-16 design maps at Site Class D and Risk Category II, the short-period design acceleration at Oklahoma City falls in the B band, so the stored A understated the requirement for the state's largest metropolitan area. Two places in Oklahoma are higher still and B does not cover them: Norman computes to C, and Lawton and the surrounding Comanche County area compute to D because of the Meers fault, a young surface-rupturing fault that produces a sharp local peak in the national seismic hazard model. Anyone building near Lawton must use the local figure and not this one. Tulsa and the panhandle compute to A. Nothing else on this row was changed. Termite risk heavy encodes the moderate to heavy band of the IRC map, which is the right band for Oklahoma. The 115 mph wind speed is an ultimate design wind speed at Risk Category II and does not represent tornado loading, which the residential code treats separately. The winter design temperature of 5 degrees Fahrenheit sits below the entire statewide range published in the State of Oklahoma residential Manual J design criteria, which runs from about 12 to 25 degrees; it was left alone because no single adopted state value exists, but do not size heating equipment from it. Frost depth and ground snow load were not confirmed against an adopted table. 2026-08-12 snow-load audit. Oklahoma publishes no ground snow load at all, and min and max are deliberately left NULL. This is a confirmed finding with adopted text behind it, not a gap in searching. The Oklahoma Uniform Building Code Commission has adopted the 2018 International Residential Code, effective 14 September 2022 and still current. The permanent rule reproduces Table R301.2(1), Climatic and Geographic Design Criteria, cell by cell in narrative form, and it records exactly one state-filled value in the entire first part of that table: the Ice Barrier Underlayment Required cell, which the rule says "has been filled in with the word 'NO' to indicate Ice barrier underlayment is not required in Oklahoma." Every other cell is delegated. Of the ground snow load cell the rule says it "has been left blank for the authority having jurisdiction to complete based on local conditions as required in footnote 'o'," and it states footnote o as: "The jurisdiction shall fill in this section of the table using the Ground Snow Loads in Figure R301.2(6)." So the ground snow load in Oklahoma is whatever the local building official enters, read off the national map figure, and the state sets no floor, no ceiling and no county schedule. The same delegation applies to three of the four other values stored on this row, which materially changes how they should be read. The rule leaves the wind speed cell, the seismic design category cell, the frost depth line cell, the termite cell and the winter design temperature cell all blank for the authority having jurisdiction. The stored wind speed of 115 mph, seismic design category B and frost depth of 18 inches are therefore not Oklahoma state-published values and no Oklahoma authority asserts them; they are derived figures, the seismic category from the USGS ASCE 7-16 service as described above. None of the four were changed in this pass, because each remains the best available summary, but none can be cited to the state code. Anyone needing the legally operative number must read it off the adopted ordinance of the specific municipality or county. The earlier note's caution that frost depth and ground snow load were not confirmed against an adopted table is now explained: no such adopted state table exists to confirm them against.