Usable area versus living area

The three terms kept apart

The footprint is the pure geometric area of a room with no assessment. It is the starting point of every calculation and, on its own, the number least likely to belong in a document, because it says nothing by itself.

Living area comes from it by applying the factors: ancillary rooms drop out, heights are staggered, outdoor space counts in part. Usable area instead describes usable space outside the living function — typically cellars, stores and outbuildings.

• Footprint: geometric, unassessed
• Living area: weighted, ancillary rooms excluded
• Usable area: usable ancillary space with no living function
• Always name which number a document means

Where the numbers typically diverge

The gap is widest in houses with a cellar and an unconverted loft. A house with 140 square metres of living area can easily carry another 70 of usable area — considerable value that nonetheless does not belong in the living-area figure.

The same happens with large balconies: the footprint is fully there, but normally only a quarter of it enters living area. Quoting both numbers does not look pedantic, it looks precise.

Presenting both in a listing

Quote living area as the headline figure and usable area as an additional note with a short explanation of what it consists of. You give nothing away and avoid the accusation of inflating areas.

Mark the rooms accordingly on the plan. The editor keeps the factors per room, so both totals derive from the same drawing rather than being maintained separately.