Granny Flat Approval Process: CDC vs DA Decision Tree (2026)

Granny flat approval process Australia still splits into a planning pathway plus a building pathway. In NSW the common fork is CDC versus DA. Other states use different names (VicSmart / Part 5, Queensland accepted development, WA R-Codes), but the logic is the same: fit a code-assessable box, or need discretionary assessment, then still get building approval against the NCC.

Last updated September 2026. This page is the decision-tree guide: when CDC-style paths fail, who lodges what, and which documents to assemble. For the national state size table and five high-level steps, use granny flat approval guide. State rules overview: regulations by state. Interactive hub: rules by state.

This is research guidance, not certification or legal advice. Confirm with your private certifier and council.

Two approvals, not one

Skipping either layer is how illegal builds and insurance headaches start. If someone tells you there’s a “no council approval” shortcut, read granny flat no council approval first. Planning says you may use the land. Building approval says you may construct. You need both.

CDC vs DA decision tree (NSW-shaped, logic travels)

Use this fork when your state offers a complying / code pathway versus a full application:

1. Is a secondary dwelling permitted on this zoning and lot type at all? If no, stop or redesign; don’t force a CDC.
2. Does the design fit numeric code standards? Size cap, setbacks, height, site coverage, landscaping area, parking, bushfire/flood overlays as applicable.
3. If yes on all ticks: complying / CDC-style pathway with a registered certifier may be available (NSW Housing SEPP CDC is the textbook example). See NSW CDC vs DA and NSW approval steps.
4. If any standard fails, or overlays trigger discretion: lodge a DA (or state equivalent) with council for assessment.
5. After planning consent: obtain building approval / construction certificate and satisfy NCC energy and condensation requirements. NCC context: NCC 2022 changes.

Official NSW lodgement sits on the NSW Planning Portal. National construction rules: NCC online via the ABCB.

When CDC-style pathways usually fail

• Floor area over the state/local cap (for example NSW 60 m² internal in common CDC settings)
• Setbacks or height that breach the code table
• Heritage, flood, bushfire or other overlays that push you out of complying development
• Torrens vs strata complications, dual occupancy conflicts, or easements through the building envelope
• Trying to use a brochure kit plan that was never checked against your lot

Kits and prefab still need site-specific approval: DIY kits hub, prefab directory, approval guide.

Documents you should expect to assemble

• Site plan with setbacks, levels and services
• Floor plans, elevations and sections
• BASIX (NSW) or NatHERS / energy certificates as required
• Stormwater and driveway notes where triggered
• Bushfire or flood reports if mapped
• Owner consent and title details

Incomplete packs are the main cause of “simple” CDC delays: certifiers won’t lodge half-drawn site plans. Budget line items: cost breakdown and cost calculator. If the survey is six years old, don’t reuse it. Levels change when neighbours fill a pool or you add a retaining wall.

Private certifier vs council: who does what

On complying pathways, a private certifier often issues the CDC and later building certificates. On DA pathways, council (or a regional assessment body) decides planning consent; a certifier still usually handles building stages. Interview certifiers on secondary-dwelling experience, not only price: you don’t want your first CDC to be their learning curve. Licence checks: verify builder licence. If they can’t name a recent granny flat in your LGA, keep shopping.

State name cheat-sheet

• NSW: CDC vs DA under Housing SEPP / EPI controls
• VIC: small second dwelling / VicSmart-style and planning scheme rules; see VIC rules
• QLD: accepted development vs assessable; QLD rules
• WA: ancillary dwellings under R-Codes with local planning scheme overlays

Always read the current instrument for your lot. Planning portals: planning.vic.gov.au, planning.qld.gov.au. If you’re comparing two states because you own land in both, don’t reuse one drawing pack. Size caps travel. Setbacks don’t.

Next step: run the fork on your lot

Check zoning and overlays, then ask a certifier whether your concept is honestly CDC-ready. Use the approval wizard for a first pass, then the national approval guide for the state size table. NSW owners: rules numbers first, NSW steps and fees second.

Frequently Asked Questions