By ANNA USHER

A developer wants to bulldoze four Mosman homes and build an eight-storey apartment block in their place, on the Cowles Road mega-lot Mosman Collective revealed last year.

The $16.23 million plan would clear four single-storey Federation semis at 92-98 Cowles Road and put 23 apartments, three basement parking levels and a building more than 27 metres tall in their place.

Developer 380 Developments recently lodged the application with Mosman Council.

It is the first detailed look at what Cowles Road will look like in the coming years.

Three “affordable” flats unlock the extra height.

Three of the 23 apartments, all two-bedroom units, would be kept as affordable housing for 15 years, run by the community housing provider Bridge Housing. After that, they can return to the open market.

Those three flats are the key to the whole design.

The site’s height limit under Mosman’s new state-set rules is 22 metres.

A state government bonus for including affordable housing lifts that cap to 28.6 metres. The plans stop just under it, at 27.24 metres.

The same bonus pushes the floor area past the standard limit, allowing the developer to build a larger block than Mosman’s own rules would normally allow.

Neighbours call it a loophole.

Six neighbours objected during the public notification period, and several say the affordable housing is a device to grab height.

“Affordable housing aims won’t be achieved in the Mosman area,” wrote one objector, who owns a unit on Cowles Road. “It is simply an opportunity to increase the height of the building.”

The owner of another Cowles Rd home said the plans lean on “affordable housing bonus provisions to obtain approximately 30% additional height and floor space while delivering only three affordable housing dwellings.”

A resident of the Bridlewood Gardens block on Brady Street was blunter. “The only people to benefit will be the developer who will sell the units after 15 years … at a substantial profit,” they wrote.

See what’s planned for Cowles Rd:

The sharpest objection comes from directly next door, where a family with two young children backs onto the site.

The plans need three basement levels. The developer’s own geotechnical report indicates the dig may reach up to 10 metres into sandstone, about 3 metres from the shared boundary.

The family says that leaves their house roughly four metres from the edge of a 10-metre-deep excavation. They point out that the same report rates the risk “Very High” before any safeguards are added.

“Our privacy, the safety and amenity of our children, and the stability of our land are our central concerns,” the family wrote.

Plans are also in for flat buildings at 89-101 Cowles Road, across the street, and at 5-9 Bond Street, directly behind.

Last May, Mosman Collective revealed nine homes on Cowles Road, from numbers 92 to 108, had been bundled into a single $40 million “mega-lot” and marketed by JLL.

This application covers four of those nine. Two of the others, at 100 and 108, are now objecting to the construction next door.

The block would provide 33 car spaces. Mosman’s own controls call for 36.

The developer’s traffic report concedes on-site loading is “not possible,” so removalists, deliveries and garbage trucks would all stop on Cowles Road, a street neighbours already call a peak-hour bottleneck into Military Road.