Granny Flat (Secondary Dwelling) NSW: A One-Weekend Feasibility

Secondary dwellings are often ideal for CDC if your site is eligible and standards are met. Run the space, services, and constraints checks below before you sketch.

Space & siting checks

• Private open space for the main dwelling must be preserved; do not “steal” it.
• Setbacks & height: Confirm max building height and eave locations on sloped sites.
• Access: Ensure safe, legible access to the secondary dwelling without compromising parking.

Services & stormwater

• Legal point of discharge confirmed; budget space for OSD if required.
• Sewer depth/grade feasible; avoid building over unless designed for.
• Power & comms routing clear of tree protection zones.

Constraints & exclusions

• BAL/flood within CDC allowances; heritage and some environmental overlays typically exclude CDC.
• Trees & TPZ: Locate footprint to avoid costly removals and structural conflicts.

Documentation shopping list

• Survey with contours and services
• Architectural plans with overshadowing/privacy diagrams
• BASIX/NCC where applicable
• Stormwater concept
• Certifier checklist (CDC) or Statement of Environmental Effects (DA)

Budget/brief reality checks

• Keep the brief tight (bedroom count, storage, laundry, outdoor area) to protect compliance and cost.
• Design wet areas back-to-back and plan the roof for clean downpipes and OSD.

FAQs

Can I rent out a granny flat? Check local controls, parking, and use conditions.
Is BASIX required? Often yes—confirm thresholds for secondary dwellings.