13. The provisions of this Part shall not be applied for the purpose of acquiring a part only of any house, manufactory or other building, if the owner desires that the whole of such house, manufactory or building should be so acquired: Provided that the owner may, at any time, before the Deputy Commissioner has made his award under section 7, by notice in writing withdraw or modify his expressed desire that the whole of such house, manufactory or building should be so acquired: Provided further that, if any question arises as to whether any property proposed to be taken under this Part does or does not form part of a house, manufactory or building within the meaning of this section, the decision of the Deputy Commissioner shall be final.