Final approval shall expire two years from the date of final approval unless the applicant has secured a building permit to commence construction. The Planning Board may extend final approval and the protection offered under § 30-15.13 for one year. Up to three such extensions may be granted. Applicants shall be required, as a condition of any extension, to reestimate improvement costs and to resubmit revised bonds in accordance therewith.

In the case of a site plan for a performance subdivision or residential cluster of 50 acres, or a corporate office and industrial park or conventional site plan for 150 acres or more, the Planning Board may extend the rights granted under final approval for such period of time, longer than two years, as shall be determined by the Planning Board to be reasonable, taking into consideration the number of dwelling units and nonresidential floor area permissible under final approval, economic conditions and the comprehensiveness of the development. The developer may apply for thereafter and the Planning Board may thereafter grant an extension of final approval for such additional period of time as shall be determined by the Planning Board to be reasonable, taking into consideration the number of dwelling units and nonresidential floor area permissible under final approval, the number of dwelling units and nonresidential floor area remaining to be developed, economic conditions and the comprehensiveness of the development.