Electronic Thesis and Dissertation Repository

Thesis Format



Master of Engineering Science


Civil and Environmental Engineering


Bitsuamlak, Girma T.


Roof pavers are commonly installed with a cavity beneath the paver that develops an internal suction pressure. These cavity pressures reduce the net pressure felt by a roof paver subject to uplift. Paver-scale parameter effects are well-understood, in this study, the effects of changing building-scale parameters such as height, aspect ratio, afterbody length, small and large scale roof obstructions, and paver to roof size ratio on cavity pressures are investigated. To do so pressure measurements were taken at the University of Western Ontario’s Boundary Layer Wind Tunnel Laboratory on a modular flat roof building model at four different heights with four different plan aspect ratios per height. It was found that size and shape of the separation vortices affect the pressure equalization capacity of the system. It was also found that the ratio of paver size to roof size greatly impacts the magnitude of peak pressures observed.

Summary for Lay Audience

Roof pavers are a commonly installed roofing element. When they are installed, there is a cavity left between them and the roof deck beneath them. When oncoming wind flows over the roof, it creates a suction pressure on the top of the installed roof pavers. However, because air is also able to flow through the cavity under the pavers, there is also a suction pressure that acts on the bottom of the paver, which reduces the net uplift that a roof paver is subject to. This phenomenon of the cavity pressure reducing the net pressure felt by a paver is called pressure equalization. Previous studies have shown how paver scale parameters such as the gap width between pavers, cavity height beneath pavers, and the thickness of the paver affect the pressure equalization capacity of roof pavers. This study investigates how building scale parameters such as building height, windward area size, after body, roof obstructions, and roof size in comparison with pave size affect the level of pressure equalization.