The Commissioner may, upon such terms as he thinks fit, allow any building to be set forward for the purpose of improving the regular line of a public street and may, with the sanction of the Standing Committee, by notice required any building to be so set forward in the case of reconstruction thereof or of a new construction.
     Explanation:—For the purpose of this section a wall separating any premises from a public street shall be deemed to be a building; and it shall be deemed a sufficient compliance with permission or requisition to set forward a building to the regular line of a street if a wall of such material and dimensions as are approved by the Commissioner is erected along the said line.