Delaware Building Codes: Local Adoption, No Statewide Residential Code

Delaware has no mandatory statewide residential building code. Counties and towns each adopt their own edition of the IRC on their own timeline — Sussex County runs the 2021 IRC, New Castle County the 2018 IRC, for example — so the operative edition and any local amendments genuinely vary by jurisdiction.

There’s no single “Delaware” figure for stair or guard geometry to cite here. As a starting point, the IRC baseline is what Delaware’s counties typically build from — 7¾ in max riser, 10 in min tread, 6 ft 8 in headroom, 36 in min width, 34–38 in handrails, 36 in guards, the 30 in guard trigger and the 4 in sphere (see the US stair & guard rules) — but confirm the adopted edition and any amendments with your county or town before relying on it.