Back in 2005, how would we know how our everyday lives would change with innovations like smartphones, social media, and streaming video services? Yet within an Indiana hospital nearly two decades ago, a decision was made as part of the main campus expansion that has stood the test of time. 

Today, as Reid Health provides an expanding array of services to the area, patients entering the main campus receive world-class care under the same Garland roof installed nearly a generation ago. Between projects, Reid Health's Director of Engineering, Jeff Cook, took a few moments to reflect on the past 17 years of supporting Reid Health’s mission through outstanding facility management.

New York University's medical center resides squarely in the middle of Lower Manhattan, one of the most dense urban centers in the world. NYU's Tisch Hospital had an out-of-warranty, aging roof that was experiencing leaks, requiring immediate attention. That alone would be a challenging project given the height of the building, the tight space for staging, and the need for a low-odor solution that would not disturb patients or staff inside the hospital. 

But add NYU's ambitious sustainability goals and the project became a truly unique challenge. Garland's NYC Territory Manager Keith DeVito partnered with NYU to develop a roofing solution that would create a leak-free environment, then added a vegetative roofing system to transform the roof to improve energy efficiency, stormwater management, and aesthetics. 

All fifty US States require a continuous air barrier as part of new construction. Code generally contains three compliance options for acceptable air leakage, or permeability, through an air barrier: 0.004 cubic feet per minute per square foot (CFM/ft²) for materials, 0.04 CFM/ft² for assemblies, and 0.4 CFM/ft² for the whole building. These standards have trended toward greater levels of air-tightness over time, and will continue to do so, with projected changes to the energy code in the future for the air leakage rate for a whole building getting to a level of just 0.25 CFM/ft². 

In spite of the ubiquity of requirements for air barrier usage, and increasing code standards, there remains a significant amount of confusion and misinformation in the roofing industry regarding air barriers and their distinctions, if any, from vapor barriers and vapor retarders. The goals of this paper are to clarify the definitions and performance characteristics of air barriers, vapor retarders, and vapor barriers; and outline conditions where the performance of an air barrier has a significant impact on the overall building.