b'DEFINING AIRTIGHTNESSIn recent years, the rationale for airtight-ness in new energy codes has been focused on energy conservation and tightness of the whole building. This significantly differs with the objectives of environmental separation in Part 5, says Douglas Watts, outgoing Chair of the Part 5 Standing Committee on the NBCC. Airtightness in Part 5 is approached from the Code aspects of health and life safety.To clarify this difference, the 2020 NBCC has been rewritten to highlight the importance of airtightness to ensure healthy indoor environ-ments that do not threaten the life safety of occupants. Watts goes on to say that energy requirements nationally are contained in the National Energy Code and provincially in the step code being use by the BCBC. The NBCC does not deal with energy requirements, which provides the rationale for the differing airtight-ness approaches between the two codes.An important aspect of this airtightness rewrite in the 2020 Code is the focus on assemblies that are used for the environmental separa-tion between dissimilar spaces and from the outdoors. The new approach deals with the potential for deterioration of materials and resulting threats to the indoor environmentVIRTUOSO IS A MID-RISE MULTI-UNIT RESIDENTIAL PROJECT COMBINING LIGHT WOOD-FRAME AND caused by air leaks. MASS TIMBER CONSTRUCTION.COURTESY OF ADERA DEVELOPMENT CORP. CREDIT: RAEF GROHNEPROUDLY CELEBRATING OUR40 THANNIVERSARYToro Aluminum is a leading window, wall and door supplier for high-rise condominiums, office buildings and hotels across Canada, the United States and Mexico.UNITIZED CURTAIN WALLUNITIZED WINDOW WALLRAILINGS(866) 320-7307 | www.toroaluminum.comFALL/WINTER 2019 15'