51Application of new regulations

51 Application of new regulations (1) A regulation or amendment to a regulation does not apply to building work for which a building permit is granted under this Act before the commencement of the regulation or amendment. (2) A regulation or amendment to a regulation does not apply to building work in respect of which a building certifier has certified in writing that substantial progress was made on the design of the building before the commencement of the regulation or amendment. (3) Despite subsections (1) and (2), a building certifier and the owner of a building may agree that a regulation or amendment to a regulation is to apply to building work referred to in those subsections and, if an agreement is made, the regulation or amendment applies accordingly.