Wind Uplift Resistance of Discontinuous Metal Roofing Systems: Literature Review and Experimental Research

Abstract

Damage to building envelopes, roofing, and wall cladding systems remains a major concern during high wind speed events such as hurricanes and tornadoes. Roofing systems are particularly vulnerable to wind damage, which can lead to extensive water leakage and damage to building contents, even when the structural system remains intact. Hence, ongoing research to improve the wind resistance of roofing materials is of great importance. This paper focuses on the wind load resistance of discontinuous metal roofing (DMR) systems, which are cladding systems assembled with individual panels that have numerous joints that facilitate air flow into and out of the cavity space between the roofing system and structural deck. Experimental research was conducted to establish whether DMR systems are air-permeable, and if so, to develop procedures that evaluate appropriate net wind pressures and pressure equalization factor (PEF) values for their design. First, wind tunnel tests were conducted on 6 by 8 ft DMR roofing specimens to measure the net wind uplift pressure coefficients on DMR systems located in simulated wind flow reattachment zones of the roof. A second experiment sought to measure the net wind pressure and PEF value across a single DMR panel subjected to suction in an air pressure chamber. Both experimental results were compared to PEF values obtained from full-scale tests conducted at the Insurance Institute for Business & Home Safety. The results showed that air permeable DMR systems experience net surface pressures related to the magnitude of external wind pressure by a PEF and so accurate determination of the PEF can only be achieved by reproducing the appropriate spatial pressure distribution on a test specimen during tests. Ultimately, this research highlights inaccuracies in current testing methodologies and the importance of importance of ongoing efforts to enhance the wind resistance of roofing materials and mitigate damage during high wind speed events.