(1)  A provision of the Plumbing Regulations does not apply to any plumbing work –

(a) for which a plumbing permit is granted before the provision commences; or

(b) if the relevant permit authority certifies in writing that substantial progress was made on the design of the work before the commencement of the provision.

(2)  Subsection (1) does not apply if the permit authority and the owner of the premises where plumbing work is to be performed agree that a provision of the Plumbing Regulations applies to the plumbing work.

(3)  Nothing in this section prevents a person from complying with a provision of the Plumbing Regulations that is not an applicable provision by virtue of this section.