Hail Study on a 15 Year Old Sprayed Polyurethane Foam Roofing System

Authors: Dean Kashiwagi, (PhD, PE), Dhaval Gajjar, (PhD), Jacob Kashiwagi, (PhD) and
Kenneth Sullivan (PhD)


The Dallas Independent School District (DISD) has utilized Alpha sprayed polyurethane (SPF) roof systems since the 1980s. Alpha SPF roof systems are high performing roof systems if installed properly and are very resistant to hail damage (hail damage is significant in the Dallas area). However, DISD, due to their low bid award procurement system, have had some poor performing roof systems installed by contractors who did not utilize performing materials and processes. The Alpha SPF roof system is now being questioned by designers who are not aware of their high performance and wanted to tear-off one of the oldest SPF roofing systems after a hail storm. This case study is on one of DISD roofs which were studied to determine the actual and potential service period based on actual performance. It was concluded that the roof is capable of lasting another 15 more years with a simple recoat (resulting in 38 years of performance at a fraction of the cost of a traditional modified roof).

Keywords: Roofing, high performance, SPF, performance measurement, Neogard.