(1)  A building permit expires on the first of the following:

(a) if the permit specifies a period within which the permit building work is to be commenced and no work has commenced within that period, on the expiry of that period;

(b) if no permit building work has been commenced under the permit and the permit does not specify a period within which the work is to be commenced, on the first anniversary of the permit application being granted under section 143 ;

(c) if the permit does not specify a period for which it is in effect and the period for which it is in effect is not extended under section 147, on the second anniversary of the permit application being granted under section 143;

(d) if the permit specifies a period for which it is in effect and the period is not extended under section 147, on the expiry of the period specified in the permit;

(e) if the period for which the permit is in effect is extended under section 147, on the expiry of the period so extended;

(f) on the issuing of a certificate of completion (permit building work) in respect of the permit building work to be performed under the permit.

(2)  A building permit is only valid while the permit is in effect.