A porch is exempt if:

  • the floor area does not exceed 30m
  • a door is retained between the porch and the rest of the house
  • there is no drainage within the porch and
  • glazing below 800mm in windows and 1,500mm in doors and sidelights is safety glazing.

You should also ensure that a porch does not cover outlets to boilers or other flues as well as the only ventilation openings to WC’s and other rooms.