Home Extension Approval in NSW — CDC vs DA
Most home extensions in NSW require either CDC or DA approval. Small internal renovations (no structural changes, no change to external appearance) may be Exempt Development requiring no approval. Buildana (Lic. 487805C) handles all approval pathways in-house.
CDC for Extensions
CDC is available for extensions that comply with the Housing Code: • Extension does not exceed height limits (8.5m/2 storeys) • Extension complies with all setbacks • Block is not heritage-listed or in conservation area • Block is not flood-prone or BAL-40+ bushfire • Extension does not change the number of dwellings
Timeline: 10–15 business days. Cost: $3,000–$6,000.
Most single-storey rear extensions in Western Sydney qualify for CDC. First floor additions are more complex — they often exceed Housing Code parameters and require DA.
DA for Extensions
DA is required when CDC criteria are not fully met. Common triggers: • First floor addition that exceeds building envelope • Heritage area • Flood-prone land • Non-compliant setbacks (e.g., side setback less than 0.9m)
DA processing: 40–90 days. Cost: $5,000–$12,000.
Buildana manages the full approval process. Contact us for a free assessment.
2026 Extension Approval Pathways — CDC vs DA in Practice
Approval pathway for an NSW home extension depends on scope, location and council overlays. Honest 2026 framework:
CDC (Complying Development Certificate) is feasible for most ground-floor extensions that: • Stay within prescriptive Codes SEPP standards: floor area cap (typically 25% of existing GFA, or specified in the SEPP), height under 8.5m, setbacks (900mm side, 3m rear). • Don't trigger overlays: no heritage, no flood (above 1% AEP), no bushfire BAL-29+, no biodiversity, no contaminated land, no acid sulphate. • Maintain solar access to neighbouring dwellings (90-minute mid-winter rule). • Don't include first-floor additions over an existing single-storey footprint (Codes SEPP allows some second-storey work but with tight controls — most second-storey jobs fail).
CDC timeframes: 10–20 business days from lodgement. Cost: $4k–$8k including private certifier fees.
DA (Development Application) is required if any CDC condition fails. DA is most commonly required for: • Second-storey additions (almost always DA) • Extensions over the 25% GFA cap • Extensions on heritage-listed properties or in heritage conservation areas • Flood-affected properties (much of Liverpool, parts of Fairfield and Blacktown) • Bushfire BAL-29+ properties • Extensions requiring setback variations • Extensions on irregularly-shaped or sloping lots that defeat prescriptive controls
DA timeframes: 60–120 days in our service area, LGA-dependent. Cost: $9k–$18k including town planner and council fees.
What pushes a project from CDC to DA in 2026: • Heritage and conservation area overlays — common in established suburbs of Fairfield (Cabramatta, Smithfield), Cumberland (Auburn, Granville, Merrylands East), Canterbury-Bankstown (Bankstown CBD, Earlwood). • Flood overlays — common in Liverpool (Hoxton Park, Prestons, Casula), Fairfield (Cabramatta West, Canley Vale). • Second-storey additions on existing single-storey homes. • Battle-axe lots and irregularly-shaped lots.
Best 2026 advice: order the s10.7 planning certificate before any serious design work. The s10.7 will tell you which overlays apply to your specific lot and shape the design and approval pathway decisions from the start.
