North Carolina

Statewide summary — confirm with your building department before designing

SNOW LOAD AUDIT, 2026. Three values on this row were changed and a fourth was left alone only under protest. North Carolina writes its own climatic and geographic table into the state residential code, and you should use that table rather than this row. GROUND SNOW LOAD, corrected from 10 to null. The North Carolina Residential Code does not assign a ground snow load at all. North Carolina strikes the model Table R301.2(1) and substitutes its own, and the first column of the North Carolina table is not GROUND SNOW LOAD but ROOF LOAD (psf), filled in with a single statewide 20. Section R301.6 then reads "The roof shall be designed for the live load indicated in Table R301.6 or the snow load indicated in Table R301.2(1), whichever is greater," pointing back at that 20 psf roof figure. The same substitution survives into the 2024 North Carolina Residential Code, whose Table R301.2 again shows ROOF LOAD 20 psf. A roof load and a ground snow load are different quantities and must not be swapped, so 20 is not being written into this column. The stored 10 psf appears nowhere in the North Carolina code and there is no statewide North Carolina ground snow load for it to represent, so the field is now null rather than wrong. MIN AND MAX, both left null. Ground snow load does appear on the commercial side. The North Carolina Building Code amends Section 1608.2 to replace the model national map with a North Carolina map, Figure 1608.2, "Ground Snow Loads Pg for the State of North Carolina," carried forward from the 2012 NCBC into the 2018 NCBC; the 2024 NCBC instead enlarges North Carolina out of the 2021 IBC figure and renames it. Figure 1608.2 is a graphic, and the OSFM and OAH amendment documents that were retrievable carry only the instruction to insert or enlarge it, not the image itself, so its values could not be read from an official source. Two things about it are known and both matter. First, it contains CS areas where, in the code's own words, "site-specific Case Studies are required to establish ground snow loads" and "extreme local variations in ground snow loads in these areas preclude mapping at this scale," and it carries upper elevation limits above which the mapped value does not apply and the load must be approved by the building official. A North Carolina maximum is therefore not merely unlocated, it is unmapped in the mountains by design. Second, at least one county reading is documented: Iredell County Building Standards publishes "The Ground Snow Load is 15 PSF per NCSBC 1608.2," a Piedmont value that on its own is enough to show the 10 psf formerly on this row was too low. One county figure is not a state range, so no minimum was written from it. FROST DEPTH, corrected from 18 to 12 inches. The North Carolina Table R301.2(1) fills the frost line depth column with a statewide 12 inches. The 2024 table repeats it as "Minimum 12 inches" with the footnote "Check with local jurisdiction for frost line depth," and NCSBC Section 1809.4 carries the same 12-inch minimum footing depth, which Iredell County restates. Note that min_footing_depth_inches on this row still reads 18 and was outside the scope of this audit; it should be reconciled to 12. SEISMIC DESIGN CATEGORY, corrected from B to C. North Carolina publishes Table R301.2(7), "Counties in Seismic Design Category C," with the note that counties not listed are in Seismic Design Category A or B. In the 2018 Residential Code the C list is Brunswick, Buncombe, Cherokee, Clay, Columbus, Graham, Haywood, Jackson, Macon, Madison, Robeson, Scotland and Swain; the 2024 Residential Code adds Transylvania and Henderson. C is the highest category the state assigns and is the correct envelope value for a statewide row. The stored B understated the requirement for Asheville and the entire western mountain block, and for Brunswick and Columbus on the southeastern coast. This supersedes the earlier USGS-derived reading, because it is the state's own adopted list rather than a computed one. WIND SPEED, left at 130 mph but still the number to distrust. The state writes its own wind map into Tables R301.2(4) and R301.2(5). Table R301.2(4) assigns 115 mph to "counties not listed," which is the great majority of the state, then names county values of 120, 130, 140 and 150 mph, with several counties split along a road or waterway: Brunswick is 140 west of Hwy 17 and 150 east of it including Bald Head Island, New Hanover is 140 west of Hwy 17 and 150 east, Onslow runs 130 west of Hwy 17, 140 east of Hwy 17 to the Intracoastal Waterway and 150 east of the waterway, Pender runs 130, 140 and 150, Dare and Hyde are 130 west of US 264 and 140 east, and Bertie, Martin and Cumberland split 120/130. Carteret is a flat 150. Table R301.2(5) handles the special mountain region counties by first floor finish elevation: below 2,700 feet 115 mph, 2,700 to under 3,000 feet 120, 3,000 to under 3,500 feet 130, 3,500 to under 4,500 feet 140, and 4,500 feet or greater 150. The true North Carolina range is therefore 115 to 150 mph. The 130 stored here is neither the state default nor the coastal maximum; treating it as an Outer Banks or Carteret number would under-design the structure. It was left in place because lowering it to the 115 default would misdescribe the coast in the other direction, but this scalar should not be relied on for any specific site. OTHER FIELDS. The North Carolina table fills the termite column with Moderate-Heavy and footnotes that protection is required in all of North Carolina under Section R318, so the requirement is universal regardless of the band label; the stored "very heavy" overstates the band but not the obligation. Winter design temperature, ice barrier underlayment, flood hazard, air freezing index and mean annual temperature are all filled in by the state table as "Local" and are set by the jurisdiction. CODE EDITION. The 2018 North Carolina Code, which is the 2015 I-Codes with North Carolina amendments, remained the governing code as of the State Fire Marshal's letter of 31 March 2025. The 2024 Code has been adopted by the Building Code Council and approved by the Rules Review Commission, but under Section 5.12(b) of S.L. 2025-2 it does not take effect until twelve months after the State Fire Marshal certifies that publication and distribution are complete and that the Residential Code Council is fully constituted; until then it may be used only as an alternate method of construction at the owner's request under Section 102.5 of the 2018 Administrative Code. Every finding above on roof load, frost depth and seismic category is the same in both editions, so the pending transition does not change these values.