Space evaders

'How big is your flat?' It's one of the most common questions Hongkongers ask each other. It's a simple enough question, but the answer is complicated - and confusing.

Most people reply by stating the gross floor area (GFA) of their apartment. This reply, however, is far from exact. According to surveyors, the GFA means the flat's total floor area - a figure that encompasses the apartment itself, but also takes in all the common facilities in the property. This common floor area is then divided by the number of flats, to give the extra space supposedly allocated for each apartment. Since there is no clear or universal definition of GFA among developers, surveyors and architects, property firms can use the term liberally to include different facilities in a project. This figure offers what many consider an inflated idea of a flat's size.

A better way to learn a flat's actual size is by its saleable area. This includes the size of the interior and the internal and external walls. The definition of saleable area is binding and, under the law, new properties' sales brochures have to include the GFA and saleable area. But developers, agents and buyers still prefer to use GFA as the price per square foot would otherwise be higher.

A close look at the GFA and saleable area at 15 large-scale residential projects in the past three decades, shows that flats in Hong Kong are getting smaller.

An apartment in Taikoo Shing or Telford Garden, built in the 1980s, has a so-called utilisation rate - the ratio between GFA and saleable area - of about 85 per cent. The figure dropped to about 80 per cent in the 1990s, and, in recent years, has stood at about 75 per cent. In other words, a 600 sq ft flat in GFA, built in the '80s, will have a saleable area of 510 sq ft. But a new flat of the same size will have a saleable area of just 450 sq ft. The difference of 60 sq ft, based on a value of $5,000 per sq ft, means the buyer unknowingly lost $300,000 worth of space.

So why are flats getting smaller? A key factor is the proliferation of luxury clubhouses with swimming pools, fitness centres and saunas.