CSA A123-21:2020 pdf download.Standard test method for the dynamic wind uplift resistance of membrane-roofing systems
1.1 This test method determines the wind uplift resistance of membrane-roofing systems when subjected to dynamic wind load cycles. The test methods are applicable to
a) mechanically attached membrane roofing systems; and
b) adhered membrane roofing systems.
The roofing system consists of a deck and roofing membrane. It includes components such as vapour barriers or retarders, insulation, cover board, etc. It is subjected to a dynamic load sequence that has been developed based on wind pressure records, simulating the effects of wind on membrane-roof assemblies.
Note: The roof membrane may be designated as the plane of air tightness.
1.2 The following limitations apply for the test methods in this Standard:
a) Method 1: Testing in accordance with this test method is limited to mechanically attached membrane roofing systems having a fastener row separation not greater than 2896 mm (114 in) and fastener in-line spacing not greater than 610 mm (24 in).
b) Method 2: Testing in accordance with this test method is limited to adhered membrane roofing systems.
1.3 The values given in SI (metric) units are the standard. The values given in parentheses are for information only.
1.4 In this Standard,“shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard;“should" is used to express a recommendation or that which is advised but not required; and "may" is used to express an option or that which is permissible within the limits of the Standard.
Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.
Notes to tables and figures are considered part of the table or figure and may be written as requirements.
4.1 The wind-induced forces on a roof and the responses of the roof system are time- and space-dependent, and thus are dynamic in nature. Design wind pressure varies with building location, height,roof slope, and other parameters.
Note: Using the local building code or wind standard or internet-based tool Wind-Rci (found at https://nrc.canada.ca/en), one can calculate the design pressure for roof assemblies.
4.2 Wind-induced load on the membrane can reach the structural support through different load paths,structural load path, pneumatic load path, or combination of structural and pneumatic load paths. To simulate the wind-induced effects on a roof, a time-dependent (dynamic) load sequence is imposed on the roof system. The procedure applied for the development of the dynamic load cycle is summarized in Annex A.CSA A123-21 pdf download.