An average can be constituted-of-or-filled-with some metres.
A (floor area) can be constituted-of-or-filled-with some square metres.
A capacity can be constituted-of-or-filled-with some cubic metres.
A (floor space) can be constituted-of-or-filled-with some square metres.
Some square metres can be constituted-of-or-filled-with (floor space).
A volume can be constituted-of-or-filled-with some cubic metres.
Some cubic metres can be constituted-of-or-filled-with timber.