Last reviewed: August 2026
CDC and DA are the two approval pathways for a granny flat in NSW. CDC is a tick-the-boxes approval issued by a private certifier: if your block meets every standard, it cannot be refused. DA is a merit assessment by your council, used when your block does not meet those standards. CDC is faster and cheaper. DA is the fallback, not a failure.
Which one applies to you is not a choice. It is determined by your block.
The rule that decides it
Both pathways sit under the State Environmental Planning Policy (Housing) 2021. The complying development standards for secondary dwellings are in Schedule 1 of that policy.
The logic is simple. Meet every standard in Schedule 1, and you qualify for CDC. Miss any one of them, and you go to DA.
There is no partial credit and no negotiating with a certifier. A certifier has no discretion, which is exactly why CDC is fast. A council does have discretion, which is why DA takes longer but can approve things CDC never could.
Side by side
| CDC | DA | |
| Who decides | Private certifier | Local council |
| Basis of decision | Compliance with a fixed checklist | Merit assessment |
| Can it be refused if compliant | No | Yes, it is assessed on merit |
| Neighbour notification | Not required | Usually required |
| Typical cost | Lower | Higher, plus council fees and consultant reports |
| Typical timeframe | Weeks | Months |
| Flexibility on design | None, standards are fixed | Variations can be argued |
BlueGum’s published timeframes are 4 to 6 weeks for CDC and 3 to 6 months for DA. Those are indicative. Council workload, requests for further information, and site complexity all move them.
The standards your block has to meet for CDC
This is the part most guides get wrong. Nearly every article you will read states NSW setbacks as flat numbers, usually “900mm to the side and 3m to the rear”. Those figures are only correct for one band of lot sizes. The standards are tiered by how big your lot is.
Here is what Schedule 1 actually says.
Lot size and zoning
- Minimum lot area of 450m² (section 54(2)(c))
- Land in a residential zone. Zone R5 Large Lot Residential is excluded from CDC, even though a granny flat is permitted there with consent (section 54(1)(a))
- Only one principal dwelling and one secondary dwelling on the lot when finished
- The lot cannot later be subdivided (section 51)
- On a battle-axe lot, the access laneway is excluded when working out the lot area
Floor area
Capped at 60m², unless another planning instrument covering your land allows more (section 52(2)(c)). This is a hard ceiling on both pathways, not just CDC.
Frontage, measured at the building line
| Lot area | Minimum frontage |
| 450m² to 900m² | 12m |
| Over 900m² to 1,500m² | 15m |
| Over 1,500m² | 18m |
Height
Maximum 8.5m above existing ground level for the granny flat itself. Detached outbuildings are capped at 4.8m and fences at 1.8m.
Side setbacks
| Lot area | Minimum side setback |
| 450m² to 900m² | 0.9m |
| Over 900m² to 1,500m² | 1.5m |
| Over 1,500m² | 2.5m |
Then add 25% of any building height above 3.8m. A 5m tall granny flat on a 600m² block needs 0.9m plus 25% of 1.2m, so 1.2m in total.
Rear setbacks
| Lot area | Base setback | Extra for height over 3.8m | Maximum |
| 450m² to 900m² | 3m | 3× the height above 3.8m | 8m |
| Over 900m² to 1,500m² | 5m | 3× the height above 3.8m | 12m |
| Over 1,500m² | 10m | 3× the height above 3.8m | 15m |
The height loading catches people out. On a 600m² block, going from 3.8m to 4.8m tall pushes the rear setback from 3m to 6m, which can cost you the whole building envelope.
Front setback
Normally the average of the two nearest dwelling houses on the same side of the street within 40m. If there are not two within 40m, it falls back to 4.5m for lots between 450m² and 900m², 6.5m up to 1,500m², and 10m above that. Classified roads require 9m.
Landscaped area
| Lot area | Minimum landscaped area |
| 450m² to 600m² | 20% |
| Over 600m² to 900m² | 25% |
| Over 900m² to 1,500m² | 35% |
| Over 1,500m² | 45% |
At least half of that landscaped area has to sit behind the building line.
Things CDC will not cover
- Basements
- A roof terrace on the topmost roof
- Land the Codes SEPP excludes, which includes certain environmentally sensitive land and heritage items
Bush fire prone land, flood control lots and land near the Siding Spring Observatory have their own additional standards in sections 57 to 59.
What if your block does not qualify?
You go to DA. That is not a dead end, and it is worth being clear about why.
A DA is assessed on merit, which means council weighs the proposal against its own planning controls and can approve something that does not fit the CDC checklist. Plenty of granny flats that fail CDC by a small margin get approved through DA without much drama.
Common reasons a Sydney block ends up on the DA path:
- Lot slightly under 450m², which is very common in the inner and middle ring
- Frontage under the tier threshold, particularly on older subdivided blocks
- Heritage listing or a heritage conservation area
- Flood affected land
- Bush fire prone land above the lower BAL ratings
- An existing structure or tree that cannot be moved
- Zone R5
DA costs more and takes longer. It is still an approval.
The honest answer on timeframes
You will see CDC timeframes quoted as 10 to 20 business days. That figure comes from certifier practice, not from the legislation, and it assumes a complete application with nothing outstanding. The clock in practice starts when your documents are actually finished, not when you first ring a builder.
Realistically, the drawings, survey, soil test and BASIX certificate take longer than the certifier does.
Frequently asked questions
Is CDC approval guaranteed if my block complies?
Effectively yes. A certifier has no discretion to refuse a complying development application that meets every standard. That is the entire point of the pathway. The risk is not refusal, it is discovering partway through that your block misses one standard.
Can I get a DA approved if CDC says no?
Often, yes. A DA is a merit assessment, so council can approve a proposal that does not meet the fixed CDC checklist. It takes longer and costs more, and the outcome is not guaranteed the way a compliant CDC is.
Does my block have to be exactly 450m²?
It has to be at least 450m². For a battle-axe block, the access handle is not counted, so a lot that looks like 480m² on the title can fall under the threshold once the laneway is excluded.
Can I build a granny flat and then sell it separately?
No. Section 51 of the Housing SEPP prevents subdivision of a lot where a secondary dwelling has been built under that part. The granny flat stays on the same title as the house.
Who works out which pathway I am on?
A builder or certifier does, from your survey, title and the planning controls on your land. BlueGum handles both CDC and DA approvals in-house and assesses which one applies as part of the site assessment.
Find out which pathway your block is on
The tiered standards above mean two blocks on the same street can land on different pathways. The only way to know is to check your specific lot area, frontage and zoning.
Check your block, or call BlueGum on 1300 060 651.
BlueGum Granny Flats is a licensed NSW builder, licence number 247388C. This article summarises the State Environmental Planning Policy (Housing) 2021 as in force in August 2026 and is general information, not planning advice. Standards can be varied by other planning instruments applying to your land. Confirm the requirements for your specific block with a certifier or your council.
