Rigid air barrier assemblies

Canada Mortgage and Housing Corporation (CMHC) gave the mandate to Petrone architects to prepare a designer and builder guide to describe the methods for installing rigid air barriers on building walls. The goal here is to demonstrate that it is possible, in a simple and effective manner, to respect the requirements of the National Building Code 1995 as pertains to maximum permeability of air barrier systems. The work done by the firm over the last twelve years made it possible to implement air tight systems in over fifty buildings in the Montreal area. The number of projects and the various conditions in which they were built led to the development of different types of air barriers. This report deals with one of these types, the rigid air barrier, made up of rigid panels the joints of which are air tight. The characteristics of the various materials making up this air tight system were first of all set during laboratory tests conducted by Canada Mortgage and Housing Corporation (CMHC). This data, dealing in particular with the panels themselves, with the various types of membranes and sealants, was very important in assessing the theoretical performance of the various systems. Implementing a air barrier system in a specific building requires, first of all, that the specific performance requirements of the system be defined. These requirements will determine the system and the materials to be used. Designing the system per se means making provision for the assembly of the materials at the various critical joints. The objectives sought at the design stage include ensuring that the desired performance is attained, durability, cost and ease of execution. The report thus proposes a series of construction details specifying the procedures for assembling the various components. Each series of details is applicable to one building type, whether this be a concrete, wood, steel, renovation, or new structure. It is not until the work is actually being done that the full value of the construction details can be appreciated. A text commenting each detail presented in this report is included to ensure proper execution. Information such as that in the specifications are found here as well as critical elements that should be verified when supervising the work. The value of the concepts presented cannot be properly assessed without verifying their performance. To reproduce as closely as possible actual implementation conditions, certain assemblies were tested on site. The results proved conclusive and corroborated, to a great extent, laboratory test results. The last section in this document thus deals with assembly performance verification methods and the results obtained.