5.6.1.

(1) Except as provided in Sentence (2), where a building component or assembly is exposed to precipitation, the component or assembly shall,

(a) minimize ingress of precipitation into the component or assembly, and

(b) prevent ingress of precipitation into interior space.

(2) Protection from ingress of precipitation is not required where it can be shown that such ingress will not adversely affect any of,

(a) the health or safety of building users,

(b) the intended use of the building, or

(c) the operation of building services.

(1) Except as provided in Sentence (2), where western cedar shakes or shingles are installed to provide the required protection from precipitation,

(a) shakes shall be not less than No.1 or Handsplit grade, and

(b) shingles shall be not less than No. 2 grade.

(2) Where western cedar shakes or shingles are installed as undercoursing to provide required protection from precipitation on vertical assemblies, they shall be not less than No. 3 grade.

(3) Except as provided in Sentence (4), where eastern white cedar shingles are installed to provide the required protection from precipitation, they shall be not less less than B (clear) grade.

(4) Where eastern white shingles are installed as undercoursing to provide the required protection from precipitation on vertical assemblies, they shall be not less than C grade.

(1) Where a material applied to a sloped or horizontal assembly is installed to provide required protection from precipitation and its installation is covered in the scope of one of the following standards, installation shall conform to the requirements of the respective standard:

(a) CAN/CGSB-37.51-M, “Application of Hot Applied Rubberized Asphalt for Roofing and Waterproofing”,

(b) CGSB 37-GP-55M, “Application of Sheet Applied Flexible Polyvinyl Chloride Roofing Membrane”,

(c) CAN3-A123.51-M, “Asphalt Shingle Application on Roof Slopes 1:3 and Steeper”, or

(d) CAN3-A123.52-M, “Asphalt Shingle Application on Roof Slopes 1:6 to less than 1:3”.

(2) Where masonry applied to vertical assemblies is installed to provide required protection from precipitation, installation shall conform to the requirements of CSA A371, “Masonry Construction for Buildings”.

(3) Where protective materials are applied to assemblies to provide the required protection from precipitation, the materials shall be installed so as to shed precipitation or otherwise minimize its entry into the assembly and prevent its penetration through the assembly.