The Insurance Institute for Business & Home Safety (IBHS) conducted a hurricane-force, wind-driven rain demonstration on Jan. 9, 2020, to show the water resistance of a FORTIFIED Roof™ built with a ZIP System Roof Assembly. ZIP System Roof Assembly is the first manufacturer-warranted roof sheathing system that meets the sealed roof deck standard for a FORTIFIED Roof. FORTIFIED Roof sealed roof deck standards are based on more than 20 years of scientific research and real-world testing.
In the demonstration, 105 fans reaching peak speeds of 105 mph and a rainfall rate of 8 inches per hour were released onto a model house outfitted with a ZIP System Roof Assembly. The wall of fans was programmed to provide gusts and triangulation of wind to replicate wind trace data collected during Hurricane Florence. The sealed roof deck built with ZIP System® sheathing and tape was 830 square feet and faced over 2,000 gallons of rain in 30 minutes, equating to about 4 inches during the 30-minute demo.
"We've calculated that an unsealed roof deck allows up to 60% of the rain that hits a damaged roof to enter into the attic. A sealed roof deck can reduce water entry by as much as 95%," said Anne Cope, Ph.D., P.E., chief engineer for IBHS. "If all the shingles came off a 2,000-square-foot unsealed roof, up to 750 gallons of water could enter the attic for every inch of rain that falls — equivalent to nine bathtubs full of water."
The resulting well-protected interior with a dry attic demonstrated that ZIP System Roof Assembly provides an effective water barrier even when completely exposed during Category 1 hurricane conditions.
"This impressive demonstration subjected the ZIP System Roof Assembly to a punishing, realistic period of high wind and wind-driven ran. The rain downpours and wind gusts simulated those that occurred during Hurricane Florence,' said Kurt Koch, vice president of product engineering and quality for Huber Engineered Woods. "We couldn't be happier with the results — ZIP System Roof Assembly really delivered as a sealed roof deck solution. We are proud of the team and their accomplishments to create the first fully warranted roof sheathing system that meets the sealed roof deck standards for a FORTIFIED roof."
"We've calculated that an unsealed roof deck allows up to 60% of the rain that hits a damaged roof to enter into the attic. A sealed roof deck can reduce water entry by as much as 95%." —Anne Cope, Ph.D., P.E. Chief Engineer, IBHS
ZIP Roof System Provides Continuous Water Barrier
ZIP System Roof Assembly is a streamlined approach to a sealed roof deck using integrated sheathing with a built-in, weather-resistive underlayment and taped seams. It eliminates the need for felt and provides a continuous water and air barrier that helps meet FORTIFIED Roof standards to keep the water out, even in a high-wind-driven rain event.
Since its introduction in 2006, ZIP System sheathing and tape has been widely adopted by construction teams as a replacement for traditional sheathing and housewrap or felt. Completed with taped panel seams using high-performance ZIP System™ flashing tape, the system helps achieve quicker dry-in and reduces the risk of re-work, while providing advanced moisture protection and reduced air leakage.
The IBHS mission is to conduct objective, scientific research to identify and promote effective actions that strengthen homes, businesses and communities against natural disasters and other causes of loss. Learn more about IBHS at disastersafety.org.