65 Muston Street, Mosman
STATE SIGNIFICANT DEVELOPMENT APPLICATION
Artist's impression - 65 Muston Street, Mosman (View from standing eye level)
For 65 Muston Street Mosman, Prosker Property is seeking approval for a nine-storey residential building comprising:
13, three-bedroom apartments including 3 affordable rental homes for moderate income workers. This could include essential workers such as nurses and teachers.
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Residential amenities including a gym, golf simulator, and wellness facilities
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Four levels of underground parking with 26 residential spaces, 3 visitor spaces including a car wash bay, accessed via Redan Lane.
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Removal of 7 trees and inclusion of deep soil landscaping to plant 38 new trees, including 18 mature trees.
Due to the sloping nature of the site, the Muston Street frontage presents as a seven-storey building.
The proposal will be lodged as a State Significant Development Application (SSDA) with the NSW Department of Planning, Housing and Infrastructure (DPHI) in early 2026.
About 3-6 months after lodgement, DPHI will publicly exhibit the proposal alongside all technical reports. At this point, the community can make formal submissions to DPHI. Prosker are sharing early plans with the community before public exhibition. To view the site plan, elevation diagrams and shadow diagrams, click here​.
About 9 months after lodgement, DPHI will review the application, issue formal comments, and make a decision on the planning application.
Muston Street - Frequently Asked Questions
Why is this a State Significant Development Application?
In NSW, for an infill affordable housing development to be classified as State Significant Development (SSD), it must meet certain capital investment value (CIV) thresholds set out in the Environmental Planning and Assessment Act 1979 and the State Environmental Planning Policy (Planning Systems). This project’s CIV threshold meets the requirements for SSD.
When will construction start?
If approved, Prosker anticipates construction for Muston Street will start in early 2027. Before receiving a construction certificate, Prosker and its appointed contractor must prepare several construction management plans for DPHI’s review. This may include construction traffic, noise and vibration and community communication management plans.
How long will demolition and excavation take?
Prosker is preparing various studies to inform its application. This includes geotechnical studies to determine ground conditions and site stability. Prosker anticipates this will take approximately 6 - 8 months. As a point of comparison, the demolition timeframes for Prosker’s Redan Lane project was 4 months. If approved, and before commencing demolition, Prosker will prepare various construction management plans. It is at this point where exact timing will be determined. The community will be kept up to date via this project website as more information becomes available.
How will trucks access the site during construction?
The proposed access routes will be either via Redan Lane or Muston Street. This will be confirmed once a construction traffic management plan is prepared, if approval is received.
Key considerations
Prior to lodging the proposal, the NSW Department of Planning, Housing and Infrastructure (DPHI) will issue a list of required assessments and actions that must be completed to lodge the proposal. This list is called the Secretary’s Environmental Assessment Requirements (SEARs). The SEARs are developed in consultation with government agencies and relevant service providers.
Based on the anticipated Housing Specific SEARs, the team has begun preparing several of these assessments. Key considerations of these studies are outlined below.
View analysis
The team is committed to being open and transparent about how the proposals impact these views.
Comprehensive view sharing studies are being prepared to assess how the proposal may impact key vantage points from neighbouring properties.
We are in contact with our nearest neighbours to discuss these impacts.
Privacy and onlooking
Privacy has been a key part of the design. Brick detailing on upper-level windows helps block direct views while still allowing light and fresh air in.
Balconies are designed with extended edges and planting to guide outlooks towards the wider views rather than into neighbouring yards.
Mature trees and taller planting will also provide natural screening, so the building feels private for both residents and neighbours.
Transport and traffic
Muston Street provides 26 residential spaces, a carwash bay and 3 visitor spots over three levels, accessed via Redan Lane.
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Traffic and parking have been carefully considered for both proposals. A traffic study is being prepared for the proposed Muston Street development and will be lodged alongside the SSDA for DPHI to consider in its assessment.
Indicative outcomes of this study anticipate five vehicle trips during both the morning and evening peak. This is a net increase of three vehicles per hour during these peak periods.
Construction access will be confirmed, with safety measures in place to minimise disruption.
Community engagement
Prosker Property is consulting its neighbours about its proposal for Muston Street, Mosman. Feedback provided for Muston Street will be collated into an Engagement Report to inform DPHI's assessment of the proposal.
This process is separate from DPHI’s formal consultation process during public exhibition.
If you would like to ask questions or provide feedback, please contact the team.
Solar access
In NSW, solar access requirements are outlined by the NSW Government’s Apartment Design Guide.
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This Guide states that developments should be designed to allow a minimum of 2 hours of direct sunlight to “habitable rooms”, including loungerooms, bedrooms and private open space, within and surrounding the development. The design achieves this requirement.
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This measurement is taken on the shortest day of the year (21 June) to assess the “worst case scenario”. Residents will receive significantly more sunlight across all other days of the year.
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This benchmark reflects a balance between residential amenity, urban density, and equitable solar access across multiple properties.
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To see our current solar diagrams, click here.
Heritage interface
As part of the proposal, Prosker Property has commissioned heritage studies to assess potential impacts on surrounding heritage items and propose mitigation measures.
While this study is ongoing, Prosker Property and architects Studio Johnston have sought to integrate the proposal with the surrounding character.
This includes breaking up the building’s façade, incorporating traditional materials such as brick, terracotta tiles and sandstone, setting back upper levels to reduce bulk, and keeping landscaping in line with the street, all to fit in with and respect nearby heritage buildings.
Construction
If approved, Prosker Property will develop and implement a Construction Management Plan which will outline how construction will be managed, including ensuring potential impacts on neighbours are minimised.
This will be achieved through using best practice mitigation measures including the use of dust and noise screening, considered construction hours and minimising construction traffic impacts on local roads.
Prior to receiving a construction certificate, the Construction Management Plan and any associated plans will require approval from DPHI.
The community will also be notified before construction commences.