(1) This Article applies to the determination of wind load to be used in the design of materials, components and assemblies, including their connections, that separate dissimilar environments or are exposed to the exterior, where these are,
(a) subject to wind load, and
(b) required to be designed to resist wind load.
(2) Except as provided in Sentence (3), the wind load referred to in Sentence (1) shall be 100% of the specified wind load determined in accordance with Article 4.1.7.1.
(3) Where it can be shown by test or analysis that a material, component, assembly or connection described in Sentence (1) will be subject to less than 100% of the specified wind load, the wind load referred to in Sentence (1) shall be not less than the load determined by test or analysis.
(4) Except as provided in Sentence (5), the wind uplift resistance of membrane roofing assemblies shall be determined in accordance with the requirements of CSA A123.21, “Dynamic Wind Uplift Resistance of Membrane-Roofing Systems”.
(5) Membrane roofing assemblies with proven past performance for the anticipated wind loads need not comply with Sentence (4).