Calculations based on AAMA/WDMA/CSA 101/I.S. 2/A440-08 (NAFS-08) AND CSA A440S1-09 with update no. 1 (CANADIAN SUPPLEMENT TO NAFS-08). For British Columbia Part 9 buildings of no more than 10 m in height, measured from grade, please click here.
A Terrain Type – definitions from NBC 2010.
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 Grade for Product Classes other than R may be higher. Refer to NAFS-08 for information about Product Classes.
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 A440S1-09 to confirm your calculations. Consult with a lawyer, accountant, and insurance professional before making any decisions.