The Chief Executive Officer shall on receipt of the notice under section 242 of this Act cause the building to be inspected either by himself or by the officer authorised by him in his behalf in order to ensure that the building has been completed in accordance with the sanction given and issue completion certificate provided that the person seeking the completion certificate shall assist the Chief Executive Officer in inspection of such building:
     Provided that the building shall not be occupied for habitation unless a certificate is issued by the Chief Executive Officer or an officer authorised by him in this behalf:
     Provided further that if the Chief Executive Officer fails within a period of thirty days after the receipt of the notice of completion, to communicate his refusal to issue such certificate, such certificate shall be deemed to have been granted.