Connecticut

Statewide summary — confirm with your building department before designing

Two values were corrected by this audit, both against Connecticut's own adopted tables. Wind speed corrected from 110 to 120 mph because 110 mph is not assigned to any Connecticut municipality. The 2022 Connecticut State Building Code adds Appendix AY to the 2021 IRC portion and Appendix P to the 2021 IBC portion, and those appendices assign an ultimate design wind speed to every one of the 169 municipalities. The lowest is 115 mph in the northwest hills, the highest is 129 mph at Stonington, and 120 mph is the value assigned to Hartford, Bridgeport, Stamford, Danbury and Norwalk and to 96 of the 169 towns. New Haven is 125 mph and the southeastern shoreline from Old Saybrook through East Lyme, Waterford, New London, Ledyard, North Stonington and Groton runs 126 to 129 mph, so a shoreline project must take its own municipal value and must not use this row. Winter design temperature corrected from 0 to 7 F because the state amended Table R301.2 states 7 F as a single statewide figure. Ground snow load was not changed but must not be read as a statewide number. Connecticut fills in Table R301.2 itself and leaves exactly two cells to a municipal appendix: ground snow load and wind speed, both "As set forth in Appendix AY." Appendix AY assigns every municipality 30, 35 or 40 psf. 30 psf covers 107 towns including Hartford, Bridgeport, New Haven and Stamford; 35 psf covers 44 towns; 40 psf covers 18, all in the northwest Litchfield hills (Canaan, Colebrook, Cornwall, Goshen, Kent, Norfolk, North Canaan, Salisbury, Sharon, Torrington, Warren, Winchester) and the northeast corner (Eastford, Pomfret, Putnam, Thompson, Union, Woodstock). The 30 psf on this row is therefore the statewide floor and the value for the four largest cities, not a value good anywhere in the state. Appendix P of the IBC portion lists the same ground snow load for each municipality, so the two state appendices agree. Connecticut also deletes IBC Table 1608.2 and Figures 1608.2(1) and (2), and deletes IRC Figures R301.2(3) and R301.2(4), so the national snow maps have no force here. Three further values are now confirmed directly from the state amended Table R301.2 rather than inferred: frost line depth 42 inches, weathering severe, termite moderate to heavy. Seismic design category B is also given as a single statewide value in that table, and it agrees with the USGS ASCE 7-16 design maps read at Site Class D and Risk Category II for Hartford, Bridgeport, New Haven and Stamford, where short period design accelerations run about 0.20 to 0.28 g. Appendix P prints per-municipality Ss and S1 values if you need the underlying numbers.