A “dual-key unit” is an apartment that can be sub-divided into two apartments but share a common main entrance. These have grown in popularity in recent years. Originally intended for three-generation families living under one roof, these homes also appeal to investors, says Alice Tan, the director and head of consultancy and research at Knight Frank.

The first dual-key units in private condominiums were launched in 2009 with 15 units offered at Frasers Centrepoint’s Caspian project in Jurong.

Since then, from 2011 to 2014, 35 of 74 private residential and executive condo (EC) projects have offered dual-key units. A total of 1,976 dual-key units have since been launched, of which 931 are in private condos, and 1,045 in ECs. The proportion of dual-key units within projects has increased from 3.4% in 2011 to 7.5% in 2013 as developers recognised the potential of this segment and buyers’ preference for the living concept.

Dual key units are also more popular among investors following the introduction of the 7% additional buyer’s stamp duty (ABSD) on second-time local homebuyers, says Tan. It allows first-time homebuyers to continue living in their own home while renting out the other sub-unit, without incurring ABSD as they are buying one unit and not two, she explains.

Owing to their price premium of about 12% to other similar-sized non dual-key units, demand has softened a little in 2013. Tan expects buyers’ continued price sensitivity to weigh on the attractiveness of such units. In 2014, developers have been adopting dual-key units as a strategy to move the sale of larger units, which have been hit hardest in the current soft residential market, especially since the implementation of the total debt servicing ratio (TDSR) last June. However, factors such as space and effective design layouts will become increasingly important as buyers become more price-sensitive and look to maximise their dollar value, says Tan.