| Research Program
For the most part, the theoretical basis used to develop the concepts presented in the report were based on the results of a literature review of laboratory tests conducted on materials, either separately or in relatively simple assemblies.The concepts presented are also based on the author's experience in producing some 50 airtight buildings since 1982. Verification procedures undertaken on two of the author's buildings using infrared thermography are also described in the report.
Results
Rigid air barrier systems are generally composed of three types of materials: rigid air barrier materials, sealing membranes and sealants.
The rigid air barrier materials must be sufficiently airtight and must be able to resist structural loads. Light concrete panels, plywood or water resistant gypsum board are suitable materials. Care must be taken to protect the gypsum board from rain during construction. Plywood has vapour retardent characteristics so it must also be used with caution to avoid creating a second vapour barrier on the cold side of the dew point. The method of fastening the rigid panels back to the building structure has been found to be crucial to the performance of the system. In one research project, seven of ten test samples failed to resist the structural loads, with most of the failures occurring at the fastening points. Typically-used fastener spacings are not adequate. For example, for gypsum board air barriers, a spacing of 200 mm along the studs and 150 mm at the bottom and top plates is recommended. Similar spacings are also recommended for light concrete panels and plywood, although specific test results for these materials are not available. | 