Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Civil and Environmental Engineering

Supervisor

Gregory Kopp

Abstract

Residential vinyl siding cladding system failures have been observed in high wind events. North American vinyl siding design standards allow a 64% pressure equalization factor, which yield relatively low wind load resistance for these products. The allowance is based on testing, which is questioned based on the literature review. The modified discharge equation analytical model, developed by others, accurately predict extent of pressure equalization found in scaled wind tunnel measurements. The model provides value in informing testing standards, product design and forensic investigations. However, it has only been validated based on scaled wind tunnel testing which may present scaling effect errors. In this study, the analytical model is verified through testing of a full-scale simplified cladding system, a dataset collected from full-scale wind tunnel testing is analyzed, and the model is adapted to vinyl siding and compared to full-scale wind tunnel test measurements. Wall friction losses, discharge losses, and inertial effects are evaluated using the full-scale simplified cladding system. Wall friction losses were found to fall between those predicted for fully developed laminar and turbulent flow models for steady flows. Discharge losses for orifice flows into a deep (9.46mm) cavity best fit the sharpedged orifice equation while application of entrance/exit, elbow, and tee loss coefficients best fit orifice flows into a shallow (2.58mm) cavity. Use of effective slug lengths are able to capture inertial effects found in unsteady measurements. Analysis of a full-scale wind tunnel dataset for vinyl siding clad walls suggest negligible influence by sheathing air leakage and flexibility. The analytical model used in the first part of the study was found in this final part to accurately predict vinyl siding pressure equalization performance. The model is then used to show that a factor of 10 increase in open area and a reduction of cavity depth to 4mm was required for the 64% allowance in the code.

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