Parece que a Geórgia revisa seu código de construção frequentemente. Eu não encontrei uma revisão para 2005, mas a edição de 2006 foi OCR escaneada e publicada aqui .
Na seção 1009.3, há isto:
1009.3 Stair treads and risers Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. Stair tread depths shall be 11 inches (279 mm) minimum. The riser height shall be measured vertically between the leading edges of adjacent treads. The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge. Winder treads shall have a minimum tread depth of 11 inches (279 mm) measured at a right angle to the tread's leading edge at a point 12 inches (305 mm) from the side where the treads are narrower and a minimum tread depth of 10 inches (254 mm).
(Limpei os defeitos do OCR).