5.1.4.1.

(1) Building materials, components and assemblies that separate dissimilar environments or are exposed to the exterior shall be designed and constructed to provide sufficient capacity and integrity to resist or accommodate,

(a) all environmental loads, and effects of those loads, that may reasonably be expected having regard to,

(i) the intended use of the building, and

(ii) the environment to which the materials, components and assemblies are subject, and

(b) all structural loads, and effects of those loads, that may be reasonably expected.

(2) The design and construction required by Clause (1)(a) shall comply with Subsection 5.2.1.

(3) The design and construction required by Clause (1)(b) shall comply with Subsection 5.2.2., with regard to,

(a) materials, components and assemblies, and associated loads, that are identified in Part 4,

(b) air pressure loads imposed on air barrier systems,

(c) wind up-lift imposed on roofing, and

(d) hydrostatic pressure imposed on the means of  protection from moisture in the ground.

(4) For materials, components, assemblies and loads to which Sentence (3) does not apply, the design and construction required by Clause 1(b) shall,

(a) comply with Subsection 5.2.2. for individual applicable loads and construction conforming to that design, or

(b) in the case of common materials, components and assemblies, and their installation, be based on proven past performance over a period of several years for individual applicable loads.

(5) Materials, components and assemblies separating dissimilar environments and assemblies exposed to the exterior, including their connections, that are subject to structural loads, shall,

(a) transfer such loads to the building structure without adverse effects on the performance of other materials, components or assemblies,

(b) not deflect to a degree that adversely affects the performance of other materials, components or assemblies.

(c) be designed, and constructed according to that design, to accommodate,

(i) the maximum relative structural movement that may reasonably be expected, and

(ii) construction tolerances that may reasonably be expected.