One- And Two-Family Dwellings (IRC) IRC 2024 The IRC provides minimum building regulations for one- and two-family dwellings and townhouses up to three stories. It incorporates structural, plumbing, mechanical, electrical, and fuel gas provisions. Highlights include energy storage system provisions (ESS), EV-ready homes, sleeping lofts, A2L refrigerants, and modifications to vapor barrier standards. The 2024 edition contains modern, new formatting with enhanced readability as well as QR codes in the margin to facilitate change tracking with mobile devices and includes revised hazard maps.