Structural and durability analysis of a novel re-roofing concept

Abstract

Metal roof decks in long-span light steel structures can become damaged and obsolete by corrosion should the roofing system become compromised. Re-roofing is conducted by either removing and replacing damaged areas (resulting in suspension of interior operations and lost revenue) or installing new decking directly over the damaged areas which can transfer corrosion to the new deck. This research conducts structural and durability analyses on a novel proposed re-roofing concept that installs a new metal roof deck over the existing deck by using a proprietary deck strap resulting in no interruption of interior processes. Preliminary structural analysis shows the proposed concept to be applicable to generic conditions around Southern Ontario. Recommendations for project specific structural analysis are made. Durability analysis demonstrates that the proposed concept system improves hygrothermal performance of the roof assembly in all cases except when insulation in the existing roof assembly is saturated. Saturated insulation should be removed prior to installing the re-roofing system.

Keywords:

• metal roof deck
• corrosion mitigation
• flat and low-slope roofing
• roof replacement
• re-roofing
• reduction in loss of downtime
• roof retrofit application
• structural analysis
• durability analysis
• hygrothermal performance

Additional information

Notes on contributors

Russell Richman

Russell RICHMAN. Dr. Richman completed his undergraduate, masters and doctorate degrees at the University of Toronto (Civil Engineer). Dr. Richman has researched in the combined areas of Building Science and Sustainable Buildings since 1998. Dr. Richman heads the Sustainable Buildings Group at Ryerson University. Currently, he is the Program Director of the Graduate Program in Building Science through the Department of Architectural Science. His research interests include: adapting the Passive House standard to North America’s climate, development of a Sustainable Renovation Rating Index and quantifying air-tightness in residential dwellings. As a registered professional engineer (ON), Dr. Richman continues to practice, providing expert opinion on a variety of building envelope related projects in Canada and internationally.

Evan Bentz

Evan BENTZ. Dr. Bentz completed his doctorate degree at the University of Toronto (Civil Engineering). Dr. Bentz is a professor in the Structural Engineering Research Group. His research interests include: Numerical modelling of reinforced concrete behaviour; Technology transfer applications for research on shear and torsion; Service life modelling of reinforced concrete structures; Analysis of ancient structures by modern methods: Response-2000 program; Membrane-2000 program;

Denver Jermyn

Denver JERMYN completed his undergraduate engineering degree in Biological Engineering at the University of Guelph (Ontario, Canada). He is a graduate of the Sustainable Buildings Group at Ryerson University. His research interests include: energy efficient retrofits, building envelope systems, hygrothermal performance and energy modelling. Denver is currently working as an engineer at CDW Engineering (Toronto).

Chang Sun

Chang SUN graduated from the Department of Civil Engineering at the University of Toronto. He was part of the structural engineering research group. Chang is currently working as an engineer in China.