Drift Snow Loads on Multilevel Roofs

Abstract

A database of snowdrift case histories on multilevel flat roofed structures has been established and is statistically analyzed. Drifted snow loads on multilevel roofs account for a large percentage of the roof losses in the U.S. However, little quantitative information is presently available about factors which influence drift formation. The process of drift formation is discussed; and a relationship between drift height and ground snow load, roof lengths, and roof elevation difference, obtained using multiple linear regression is presented. Drift slope and snow density characteristics are also studied. Finally, snowdrift case histories are compared with drift load provisions in building codes and load standards and recommendations for future research are made.