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Alterations + Additions to Existing
Modifying an existing dwelling — extensions, second-storey adds, internal reconfigurations.
A$50,000–600,000 build cost6–20 weeks DA timeline
Typical pathway by state
NSW: Exempt for minor; CDC for compliant additions; DA otherwise
VIC: May be exempt under Building Reg; otherwise Planning Permit (especially in HO)
QLD: Building Approval only (no MCU if use unchanged)
Required documents
- ✓Site Survey (if external)
- ✓Architectural plans showing existing vs proposed
- ✓Demolition plans
- ✓BASIX (NSW — for alts+adds > A$50,000)
- ✓Engineering for structural changes
- ✓Neighbour notification (DA pathway)
Optional / triggered docs
- •Heritage IS (if listed or in HCA)
- •BAL (if BFPL)
- •Arborist (if tree impact)
- •Acoustic (if new bedroom near road)
Typical consultants
Key compliance checks
- ▸Existing GFA + proposed addition vs FSR limit
- ▸Increased height vs height limit
- ▸Setback compliance for new walls
- ▸Privacy impact on neighbours
- ▸Overshadowing increase
- ▸Heritage character (if applicable)
- ▸Existing services capacity (sewer, water, power)
Notes
Alts+adds are the highest-volume DA category for owner-occupiers. NSW CDC pathway under SEPP can fast-track significantly. Heritage Conservation Areas (HCA) often turn what would be exempt into a full DA.
Recommended pack for this project type
Lite DA Pack A$299