The design of air and vapour barriers is fairly straightforward for the “perfect” or “universal” wall, where the moisture, air, and vapour barrier are a single membrane installed outboard of the building structure along with exterior insulation. This wall design works for any environmental condition. However, the universal wall is not always practical and there are a few more considerations when the thermal insulation is split and the control layers are separated. Regardless of design, ensuring air barrier continuity is the vital consideration for successful installations of air barriers when performance expectations must be met. This presentation outlines the design and installation considerations ranging from the universal wall to code minimums with regard to the design and installation of air and vapour barriers for multi-unit residential buildings.
Patrick Roppel, Building Science Specialist, manages the Building Performance Analysis Department at Morrison Hershfield. He is a Building Science Specialist with a technical focus on evaluating the performance of building envelope assemblies through testing, monitoring, and numerical simulation. Patrick manages and provides technical oversight on new construction and retrofit projects, investigation and assessment of existing buildings, and building science research.