law: 236. Definition.
  In this Chapter, unless the context otherwise requires, the expression "to erect a building
  " means
  (a) to erect a new building on any site whether previously built upon or not;
  (b) to re-erect
  (i) any building of which more than one-half of the cubical contents above the level of the plinth have been pulled down, burnt or destroyed; or
  (ii) any building of which more than one-half of the superficial area of the external walls above the level of the plinth has been pulled down; or
  (iii) any frame building of which more than-half of the number of the columns or beams in the external walls have been pulled down;
  (c) to convert into a dwelling house any building or any part of a building not originally constructed for human habitation or, if originally so constructed, subsequently appropriated for any other purpose;
  (d) to convert into more than one dwelling house a building originally constructed as one dwelling house only;
  (e) to convert into a place of religious worship or into a sacred building any place or building not originally constructed for such purpose;
  (f) to roof or cover an open space between walls or buildings to the extent of the structure which is formed by the roofing or covering of such space;
  (g) to convert two or more tenements in a building into a greater or lesser number;
  (h) to convert into a stall, shop, warehouse or godown, stable, factory or garage any building not originally constructed for use as such or which was not so used before the change;
  (i) to convert a building which when originally constructed was legally exempt from the operations of any building regulations contained in this Act or in any bye-laws made thereunder or in any other law, into a building which had it been originally erected in its converted form, would have been subject to such building regulations;
  (j) to convert into or use as a dwelling house any building which has been discontinued as or appropriated for any purpose other than, a dwelling house.