In the 1985 edition of the National Building Code of Canada (NBCC) the intensity of the specified snow load at any location on a roof is obtained by multiplying the ground snow load for the building locale by a series of factors. These factors reflect the overall reduction in average snow loads on roofs as compared with that on the ground, the effect of exposure to wind, the effect of roof slope, and the effect of drifting, sliding, creep, and drainage.The four loading cases for the design of curved roofs suggested in the Commentary on snow loads accompanying the 1980 NBCC were examined by determining, for roofs of circular cross section, the variation across the span of load intensity, shear force, and bending moment for a wide range of spans, ground snow loads, and roof edge slopes. The purpose of the examination was to fully describe known inconsistencies arising from these loading cases.A new case for drift loading was developed (case III) that, when used with "full" or "uniform" loading and with the unbalanced loading developed for the 1977 NBCC (case II), eliminates or at least reduces the inconsistencies. With this new loading case and the derivation of a formula to define when to switch from loading case II to the new case III the designer now has to consider only one unbalanced loading condition rather than three as before.A simplified method for establishing specified load intensities, shear forces, and bending moments, suitable at least for preliminary design, is also presented. Key words: bending moments, curved roofs, drifts, load intensity, shear force, snow load factors, wind.