law: The Delhi Municipal Corporation Act, 1957
  334. Applications for additions to, or repairs of, buildings.-
  (1) Every person who intends to execute any of the following works, that is to say-
  (a) to make any addition to a building;
  (b) to make any alteration or repairs to a building involving the removal or re-erection of any external or partly wall thereof or of any wall which supports the roof thereof to an extent exceeding one-half of such wall above the plinth level, such half to be measured in superficial feet;
  (c) to make any alteration or repairs to a frame building involving the removal or re-erection of more than one-half of the posts in any such wall thereof as aforesaid; or involving the removal or reerection of any such wall thereof as aforesaid to an extent exceeding one-half of such wall above plinth level, such half to be measured in superficial feet;
  (d) to make any alteration in a building involving-
  (i) the sub-division of any room in such building so as to convert the same into two or more separate rooms, or
  (ii) the conversion of any passage or space in such building into a room or rooms;
  (e) to repair, remove, construct, reconstruct or make any addition to or structural alteration in any portion of a building abutting on a street which stands within the regular line of such street;
  (f) to close permanently any door or window in an external wall;
  (g) to remove or reconstruct the principal staircase or to alter its position; shall apply for sanction by giving notice in writing of his intention to the Commissioner in such form and containing such information as may be prescribed by bye-laws made in this behalf.
  (2) Every such notice shall be accompanied by such documents and plans as may be so prescribed.