Dual-occupancy in Frankston & the Peninsula.

A granny flat is a dependent second dwelling — council allows it because a family member lives there. A dual-occupancy is a full second dwelling on the same lot, with no requirement for family relationship. Most importantly, a properly-built dual-occupancy is subdivision-ready: down the track when council planning controls evolve, the block can be subdivided and the second dwelling sold on its own title.

That “sold on its own title” pathway is worth $300K–$600K on a typical Frankston South / Mt Eliza block in 2026 prices. The extra $40K–$80K you spend over a basic 2-bedroom granny flat to make the build subdivision-ready is the cheapest capital you’ll ever raise.

What “subdivision-ready” actually means.

• Independent services: Separate water meter, separate sewer connection, separate electrical mains (not just sub-board), separate gas if applicable
• Independent stormwater: Own legal point of discharge, not piggybacking the main dwelling’s system
• Independent access: Own driveway from the street, own front gate, own pedestrian path
• Boundary-compliant siting: All setbacks designed assuming a future title boundary running between the two dwellings
• Independent parking: Own dedicated bay (often 2 on a Peninsula block)
• Fire-rated separating wall: If the two dwellings share any boundary, NCC class 1a fire-rated construction

Block size requirements.

Frankston City Council requires min 600m² for dual-occupancy (vs 300m² for a granny flat). Mornington Peninsula Shire requires 800–1,000m² depending on the planning overlay. The block also needs enough frontage for two separate driveways (typically 15m+ frontage), or a battle-axe layout with a 4m-wide access leg to the rear unit.

Planning permit pathway.

Dual-occupancy never uses VicSmart — always a full planning permit with full neighbour notification. Decision time 90–120 days. We engage a planning consultant for any dual-occ in Mornington Peninsula Shire — the overlays add layers of design control that a general-practice architect won’t catch first time. The planning consultant cost ($4K–$8K) is standard practice and almost always saves more than it costs.

Typical dual-occupancy budgets.

• 2-bedroom dual-occ 90m² modular, Frankston City block: $185K–$220K
• 2-bedroom dual-occ 110m² custom, Frankston South: $220K–$260K
• 3-bedroom dual-occ 130m² Mt Eliza bay block: $250K–$320K
• Battle-axe rear unit + main-house facade upgrade (combined project): $320K–$450K
• Add $20K–$40K for coastal AS 4312 spec on Peninsula bay-side