A Terrain 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.
D The minimum water resistance test pressure for the application may be higher than that required by the PG level in the NAFS standard. Verify all product ratings for code compliance
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.