Are we controlling vapor diffusion or air movement? Or both? Air barriers are required for new buildings per the IECC 2015 and IECC 2018, and the importance of air barriers cannot be overstated for energy efficiency and moisture control. We will discuss common vapor retarders and air barriers, how they’re installed, and the critical installation details as it relates to the roof and the roof/wall interface. A case study with over one million square feet of roofing will be presented to show real-world design and installation considerations and challenges. You’ll also learn that current installation of vapor retarders and air barriers over concrete, steel, and wood decks require different materials and application methods. What’s new, what’s the same, and what to think about when you design roof assemblies in different climate zones and over different types of occupancies with varying construction types.

Learning Objectives:

1. Define the differences between air barriers and vapor retarders.
2. Understand how these materials impact roof design and performance.
3. Review code requirements and how to achieve compliance.
4.  Outline design and specification requirements to set achievable performance.

Andrea Wagner Watts

Andrea Wagner Watts is the Building Science Education manager for GAF, engaging with industry professionals to provide guidance, technical support and education for roof and wall assemblies. Andrea has more than 15 years of experience in the construction industry, successfully developing multiple sealants and air/water barrier system solutions and doing building science research. She is always working to improve the overall performance of the building enclosures through application innovation, research and industry knowledge sharing. Andrea has published on building science, assembly interfaces, durability and resilience and is the holder of multiple patents. She serves as an executive board member of ABAA, is the co-chair of their Technical Committee and chairs the ASTM E06 Task Group on air barriers.