By ANNA USHER

A Sydney developer is understood to have spent around $85 million acquiring 12 homes in a top-secret amalgamation — revealed for the first time today by Mosman Collective.

If approved, numbers 21, 23, 25, 27, 29 and 31 Brierley St, and 42a, 44, 46, 48, 50 and 52 Rangers Ave in Mosman will be demolished and stitched together into a 5,638 square metre "super site" that could deliver between 80 and 100 apartments spread across eight storeys (24m).

The land, spanning three street frontages, has been earmarked by Arissa Group – led by brothers Joe and Frank Scarf – for a "mid-market" residential project, with plans to include a provision for affordable housing.

"We want to make housing achievable for people who desire to live in Mosman," Mr Scarf said, "This project will open up an opportunity for young families and professional couples to reside in the 2088 postcode."

Mr Scarf said the property deal had taken six months to negotiate with the twelve homeowners, who are believed to have made "overnight fortunes", according to one local real estate agent.

Mosman Collective understands that one of the Brierley St homeowners has also sold two more Mosman properties, which are now slated for redevelopment under the new Low and Mid Rise (LMR) Housing policy.

"It's like winning the lottery, and many of these locals have made a life-changing amount of money," the agent told Mosman Collective on the condition of anonymity.

"If this development is approved, it will bring a huge number of new residents into the area."

Mr Scarf said he hoped the site would comprise just one building, with its top floors offering harbour and city views.

He confirmed 15% of the project, if given the green light, would be allocated to affordable housing.

"The site is sloping, which will make excavation a little easier, and there will be car parking for each unit," Mr Scarf said.

"Residents can also expect a swimming pool and gymnasium."

Located 346m from Cremorne Town Centre, he would not confirm whether Arissa would apply for State Significant Development (SSD) status, which would streamline a building approval and remove Mosman Council from the decision-making process.

"Obviously, we are in the very early stages of this project, but we will be fully transparent with the community in the months ahead," Mr Scarf said.

"It is a very exciting development and one that will unlock affordable options for those who wish to purchase in Mosman."

About the properties:

• 21 Brierley St, Mosman (564sqm). Purchased in 1986.
• 23 Brierley St, Mosman (451sqm). Purchased in 2006.
• 25 Brierley St, Mosman (451sqm). Purchased in 2004.
• 27 Brierley St, Mosman (448sqm). Purchased in 1999.
• 29 Brierley St, Mosman (449sqm). Purchased in 2023.
• 31 Brierley St, Mosman (451sqm). Purchased in 2013.
• 42a Rangers Ave, Mosman (411sqm). Purchased in 2011.
• 44 Rangers Ave, Mosman (601msq). Purchased in 2014.
• 46 Rangers Ave, Mosman (451sqm). Purchased in 2007.
• 48 Rangers Ave, Mosman (451sqm). Purchased in 2005.
• 50 Rangers Ave, Mosman (451sqm). Purchased in 2014.
• 52 Rangers Ave, Mosman (451sqm). Purchased in 2023.