(1) This section sets out how to work out the open area of the walls of a place.
(2) The open area of the walls of a place is the total of the minimum areas required to fill—
(a) each gap in any parts of the walls that do not have, or are not taken under section 9 (7) to have, solid surfaces; and
(b) each gap between parts of the walls; and
(c) each gap between the walls and the nearest point of the overhead cover; and
(d) each gap between the walls and the nearest point of the floor.
Example
See example to section 9 (6).