(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.