Once the structural flood proofing design was complete, the team from Stevens worked with Gurit (USA), Inc. to design GFRP shutters and plugs to protect the home’s windows and doors from flood waters. The biggest challenge was designing shutters for the sliding doors on the house’s south side. The house required six sets of bi-folding shutters, measuring 10-feet, 7-inches tall by 7-feet, 5-inches wide. They had to be light enough to easily pull down and lock in place over the sliding doors in case of a storm. GFRP was the obvious solution. “We knew fiberglass was a great material because of its economic price point, and we also knew that we needed something that was high strength and lightweight” says King.
Laminate schedules were developed and tested using full-scale prototypes to determine the most durable and lightweight design. These prototypes and the final panels were fabricated at Aquidneck Custom Composites (ACC). The top and bottom panels were laminated in pairs on the flat table mold. The bottom panel, which needs to withstand loading from flood waters and impact from floating debris, was designed for more strength and impact resistance than the top panel. The Stevens’ team and ACC produced two prototypes, tweaking the materials and conducting finite element analyses at Gurit, before settling on the right solution.
The bottom panel features a 1.5-inch PVC structural foam core from Gurit for added strength and impact resistance, a single layer of Vectorply biaxial E-glass aligned ±45° and an outside layer of Vectorply triaxial E-glass aligned ±45/90° to reduce deflection. To save weight and reduce cost, the top panels – which carry a solar panel and are subject to wind and snow loading – were fabricated with a 1.5-inch high-density polyisocyanuate core cut at Polycel Inc. and two layers of Vectorply biaxial E-glass, the first oriented at ±45° and the second at 0/90°.
The team strengthened the mounting locations for critical hardware, such as the shutters’ marine latches, with 24lb./ft.3 glass fiber reinforced core and additional localized laminate. Both panels used a gel coat from Polynt Composites and a Vectorply .75-ounce chopped fiber mat for the skin coat and were vacuum infused with a vinyl ester resin from Polynt Composites. Once gelled, the resin cured for 12 hours, allowing for fabrication of about one pair of shutters per day. The panels were then sanded and polished to marine finish quality. Each two-panel unit weighs approximately 180 pounds.