Floor area

for the purposes of Volume Two, means in relation to a room, the area of the room measured within the finished surfaces of the walls, and includes the area occupied by any cupboard or other built-in furniture, fixture or fitting (see Figure 5 ).

for the purposes of Volume One, means—

1. (a) in relation to a building — the total area of all storeys ; and
2. (b) in relation to a storey measured over the enclosing walls, and includes—
   1. (i) the area of a mezzanine within the storey , measured within the finished surfaces of any external walls ; and
   2. (ii) the area occupied by any internal wall or partitions, any cupboard, or other built-in furniture, fixture or fitting; and
   3. (iii) if there is no enclosing wall, an area which has a use that—
      1. (A) contributes to the fire load ; or
      2. (B) impacts on the safety, health or amenity of the occupants in relation to the provisions of the BCA; and
3. (c) in relation to a room — the area of the room measured within the finished surfaces of the walls, and includes the area occupied by any cupboard or other built-in furniture, fixture or fitting; and
4. (d) in relation to a fire compartment measured within the finished surfaces of the bounding construction, and if there is no bounding construction, includes an area which has a use which contributes to the fire load ; and
5. (e) in relation to an atrium measured within the finished surfaces of the bounding construction and if no bounding construction, within the external walls .

<1>
gross floor area; usable floor area
<2> means, in relation to a room, the area of the room measured within the finished surfaces of the walls, and includes the area occupied by any cupboard or other built-in furniture, fixture or fitting
[SOURCE: BCA Vol 2 terminology]
<3> means:

1. (a) in relation to a building - the total area of all storeys; and
2. (b) in relation to a storey - the area of all floors of that storey measured over the enclosing walls, and includes:
3. (c) in relation to a room - the area of the room measured within the finished surfaces of the walls, and includes the area occupied by any cupboard or other built-in furniture, fixture or fitting; and
4. (d) in relation to a fire compartment - the total area of all floors within the fire compartment measured within the finished surfaces of the bounding construction, and if there is no bounding construction, includes an area which has a use which contributes to the fire load; and
5. (e) in relation to an atrium - the total area of all floors within the atrium measured within the finished surfaces of the bounding construction and if no bounding construction, within the external walls

[SOURCE: BCA Vol 1 terminology]
See also: usable floor area