The Massachusetts State Building Code stipulates that any permit issued shall be deemed abandoned and invalid unless the work authorized by it shall have been commenced within 6 months after its issuance; however, for cause, and upon written request of the owner, 1 or more extensions of time, for periods not exceeding 6 months each, may be granted in writing by the building commissioner. Work under such a permit in the opinion of the building commissioner, must proceed in good faith continuously to completion so far as is reasonably practicable under the circumstances.