More developers are touting skybridges in new projects, tempting buyers with the promise of greenery, meals and even workouts in mid-air.

These gravity-defying structures, made famous by HDB's Pinnacle@Duxton, will pop up in Lincoln Suites, One Shenton, Sky@eleven and Silversea.

The Quartz near Buangkok MRT station, completed this year, has one too.

One Shenton has three skybridges connecting a 50-storey skyscraper to a smaller 43-storey tower.

Two of the skybridges are part of private residential units, which can be used for dinner parties, while the third, on the 24th floor, features a gym which can be used by all residents.

Said Mr Anthony Chia, deputy general manager of design and projects for City Developments: 'It's an experience akin to the excitement on the Petronas Towers viewing gallery or crossing the Golden Gate Bridge in San Francisco.'

Lincoln Suites, a recently launched offering in Novena, also boasts a gym in the sky. Built using tempered glass and steel, the skybridge on the 24th level has a see-through floor so residents can get a workout with the world literally at their feet.

In the case of Silversea in Marine Parade, the aim was to create a common space on the 11th floor for residents to mingle. 'The design rationale was to link each pair of towers with bridges so that an uncluttered, column-free common space for the residents is created,' said Mr Chng Kiong Huat, executive director of development and planning at Far East Organization.

At Pinnacle@Duxton, 12 skybridges link seven residential blocks on the 50th and 26th floors, forming continuous sky gardens that offer a green sanctuary for residents.

A check with the Urban Redevelopment Authority (URA) and the Building and Construction Authority showed that there are no specific rules that govern the construction of skybridges in high-rise buildings.

Developers are given free rein, as long as they conform to standard building design codes.

But these lofty structures do not come cheap.

Developers estimate that it can cost more than $200,000 to build one, depending on the materials used and design complexity.

Fully covered skybridges are considered part of a condominium's gross floor area, which is pre-determined by the URA.

This means that the floor area occupied by a skybridge could have been used for another apartment unit, giving developers additional income.

At Lincoln Suites, the 32 sq m taken up by the skybridge could have been used for a $700,000 studio apartment. 'It's an extra cost but we wanted something iconic that would be the talk of the town,' said Mr Francis Koh, CEO and group managing director of Koh Brothers, one of four developers involved in the project.

'Buyers today are more sophisticated, so it is important to give them something extra.'

Developers said buyers are swooning over skybridges, and plan to build more.

Even public housing is reaching for the sky.

According to an HDB spokesman, there will be more skybridges soon as part of plans to rejuvenate the heartland. They will likely be seen at the upcoming Dawson estate in Queenstown.

But despite the soaring appeal of such bridges, prospective buyers said they will look at other factors first before signing off on a purchase.

Said corporate trainer Tay Shun Kiat, 42, who is looking for a private apartment for his mother: 'It looks really nice, but location and price are still most important to me.'