b'2020 NATIONAL BUILDING CODETHE 2020 NATIONAL BUILDING CODENew building envelope and wood construction requirementsBy Warren HeeleyW ith the publication of theof how these changes could affect the way theyfenestration compared to the very narrow 2020 National Buildingdo business once the new code is adoptedband of requirements in editions prior to Code of Canada (NBCC) ain B.C. 2015. These requirements were codified and little more than 14 monthsexpanded in the 2015 edition by using the away, the changes includedTHE BUILDING ENVELOPE North American Fenestration Standard as a in the new Code are nowPart 5 of the NBCC, entitled Environmentalreference document. This created performance coming into focus. Of particular importanceSeparation, is where the requirements for thecriteria for curtain wall, window wall, storefront are new requirements concerning the buildingbuilding envelope are primarily included. Theand architectural glazing systems which had not envelope and wood construction that bringPart 5 Committee also has responsibility forbeen included previously in the NBCC.the Code up-to-date with current standards inenvironmental separation requirements that fallIn B.C., when the 2015 NBCC requirements these sectors.under the residential section, Part 9. The keywere considered for the BC Building Code The building envelope changes involve betterchanges for this part of the code involve more(BCBC), the provincial government decided defining fenestration performance criteria,succinctly defining fenestration requirements,to not adopt new subsection 5.9.3 on other rewriting how airtightness is determined andrewriting the approach to airtightness as itfenestration assemblies into the 2018 BCBC clarifying a standard for durability. The newapplies to the building envelope and contrib- despite recommendations from the Part 5 Code will also have significant changes in theutes to a standard for durability. Committee and the building envelope industry. area of wood construction and the height ofThe new subsection in Part 5 of the 2020 wood buildings.FENESTRATION Code will see some minor revisions, and the industry is again strongly recommending that Many of these changes will impact the buildingIn the 2015 NBCC, Part 5 included a signifi- this reference be included in the new edition of envelope industry. Members should be awarecant change to the scope of application forthe BCBC.14 BCBEC ELEMENTSA BCBEC PUBLICATION'