calculations based on AAMA/WDMA/CSA 101/I.S. 2/A440-11 (NAFS-11) AND CSA A440S1-17 CANADIAN SUPPLEMENT TO NAFS-11
ATerrain Type - definitions from NBC 2015.
Open terrain - where open terrain is level terrain with only scattered buildings, trees or other obstructions, open water or shorelines.
Rough Terrain - where rough terrain is suburban, urban or wooded terrain extending upwind from the building uninterrupted for at least 1 km or 20 times the height of the building, whichever is greater.
B The minimum Performance Class for building code Part 9 compliance is R, project specifications may require a higher Performance Class, please review the specification and NAFS 2011 for more information.
C An A3 or Fixed rating exceeds the performance of an A2 rating.
Fenestration Canada Disclaimer: Nothing on this site constitutes legal advice. These calculations are presented as general guidance and technical information from Fenestration Canada - a not-for-profit organization. Review CSA A440S1-17 to confirm your calculations. Consult with a lawyer, accountant, and insurance professional before making any decisions.