IBHS researches variables that affect water entry into buildings during wind-driven rain events such as tropical storms and hurricanes. Results inform IBHS FORTIFIED Standards and other guidance for reducing this type of damage.

In 2011, IBHS conducted a first-of-its-kind full-house examination of how wind-driven water penetrates common types of openings in residential roof systems. The study was modeled on real-world, post-event damage assessments in areas where winds were strong enough to blow off the roof cover, but not strong enough to tear off roof sheathing or decking, which leaves roofs vulnerable to water intrusion by wind-driven rain.

A full-scale duplex building was constructed where one half of the roof deck was sealed and one half was not sealed prior to installing an asphalt shingle roof covering. Shingles were then manually removed and the duplex was subjected to simulated wind-driven rain. A custom drainage system was used to quantify the amount of water that penetrated the roof.

Results of this study are incorporated into the IBHS FORTIFIED Standards, which recommend simple and inexpensive procedures to strengthen roofs against this type of water intrusion.