47.5 MB - The Whole Building Design Guide

Figure 3-92:To avoid walkway padblow off, as occurredon this hospital roof,walkway pads are notrecommended. HurricaneCharley (Florida, 2004)Parapets: For low-sloped roofs, minimum 3-foot high parapets arerecommended. With parapets of this height or greater, the upliftload in the corner region is substantially reduced (ASCE 7 permitstreating the corner zone as a perimeter zone). Also, a highparapet (as shown in Figures 3-78 and 3-118) may intercept windbornedebris and keep it from blowing off the roof and damagingother building components or injuring people. To protect baseflashings from wind-borne debris damage and subsequent waterleakage, it is recommended that metal panels on furring strips beinstalled over the base flashing (Figure 3-93). Exposed stainlesssteel screws are recommended for attaching the panels to the furringstrips because using exposed fasteners is more reliable thanusing concealed fasteners or clips (as were used for the failedpanels shown in Figure 3-58).MAKING CRITICAL FACILITIES SAFE FROM High Wind3-113