Uplift Capacity and Impact Resistance of Roof Tiles

Roof coverings, particularly barrel tiles, have experienced significant damage over the last few years from storms, even weaker storms such as Category 1 Hurricane Wilma in 2005. Efforts have been made to ban mortar-set attachments in southern Florida in favor of adhesive sets. Moreover, some homeowners have generalized the poor performance of clay or concrete tiles in favor of one or the other. This study aims to address whether there is a significant difference in the uplift capacity and impact resistance of field and ridge tiles of clay and concrete with either mortar-set or adhesive-set attachments. The detailed experimental study revealed the strongest system to be concrete tiles with mortar, both for uplift capacity and impact resistance. Although concrete tiles bond to mortar much better than clay tiles, clay tiles adhere better to the foam adhesive. Concrete tiles were also shown to perform better than clay tiles when impacted by a traveling projectile. Test results do not support the ban on the use of mortar for hip and ridge tiles. It is suggested that any such ban on mortar should be limited to clay tiles only. The study also showed cyclic testing to more accurately represent the uplift capacity of tiles for real hurricane conditions. In contrast, the monotonic testing used by tile manufacturers across the industry was found to overestimate the uplift capacity of tiles by as much as 40%.