6SIn section 11 (affirmative burdens: shared liability), after subsection (3) there shall be inserted—
“(3A)For the purposes of subsection (3) above, the floor area of a flat is calculated by measuring the total floor area (including the area occupied by any internal wall or other internal dividing structure) within its boundaries; but no account shall be taken of any pertinents or any of the following parts of a flat—
(a)a balcony; and
(b)except where it is used for any purpose other than storage, a loft or basement.”.