Last reviewed: August 2026
Failing the complying development checklist is not the end of the project. It means the fast approval pathway is closed and you move to a development application, where council assesses your proposal on its merits rather than against a fixed list. Plenty of granny flats that miss the checklist by a small margin get approved this way.
You usually have five options. Here they are, and how to work out which one applies.
First, find out exactly what failed
This matters more than it sounds, because the options depend entirely on which standard you missed.
| What failed | How fixable |
| Lot under 450m² | Not fixable. DA only. |
| Frontage under the required width | Not fixable. DA only. |
| Zone R5 Large Lot Residential | Not fixable for complying development. DA only. |
| Heritage item or conservation area | Not fixable. DA only. |
| Flood or bush fire affected | Usually DA, sometimes buildable with extra standards |
| Setbacks cannot be met | Often fixable by redesign |
| Landscaped area short | Often fixable by redesign |
| Building too tall | Usually fixable by redesign |
| Existing structure in the way | Often fixable by removing it |
| Sewer main under the build area | Fixable, at a cost |
The first four are facts about your land that no design can change. The rest are about the building, and a building can be changed.
Option 1: Redesign so it does comply
Worth exhausting before anything else, because complying development stays the fastest and cheapest route.
The most common fixes:
- Drop the height below 3.8m. Height above 3.8m increases both side and rear setbacks, and the rear loading is three times the extra height. Coming down under 3.8m can hand you back several metres of building envelope.
- Make the granny flat smaller. A 45m² two bedroom fits where a 60m² will not.
- Move it. A different position on the block can resolve a setback or a landscaping problem.
- Remove a structure. An old shed, a disused slab or a pool can be what is consuming your envelope.
- Change the roof form. Roof design affects overall height.
A good designer will run these before telling you the block does not work.
Option 2: Go to a development application
The standard path when the block itself is the problem.
A DA is a merit assessment. Council weighs your proposal against its own local planning controls and can approve things the fixed checklist cannot. A block that is 430m² instead of 450m², or has 11m of frontage instead of 12m, is exactly the kind of near miss that DAs exist for.
| CDC | DA | |
| Basis | Fixed checklist | Merit assessment |
| Can approve a near miss | No | Yes, at council’s discretion |
| Typical timeframe | Weeks | 3 to 6 months |
| Cost | Lower | Higher, plus council fees and consultant reports |
| Outcome certainty | Certain if compliant | Not guaranteed |
The trade-off is time, cost and certainty. You are asking rather than qualifying.
Option 3: Convert space inside the existing house
Often overlooked, and genuinely useful on tight blocks.
A secondary dwelling located within the principal dwelling has a different and simpler set of requirements. It needs to meet the Building Code, must not be on environmentally sensitive or heritage land, and can involve no external alterations beyond adding one entrance. It still cannot exceed 60m².
If you have a large garage, an under-house area or a rarely used wing, this can deliver a self-contained dwelling without touching the yard, the setbacks or the landscaped area requirements at all.
Option 4: Fix the physical obstacle
Some failures are practical rather than legal.
- Sewer main under the build zone. A build-over application or a diversion. Both cost money and time, but both are done routinely.
- A tree. Removal may be possible with council consent, or the building can move outside the protection zone.
- An easement. Usually you cannot build over it, but you may be able to build around it.
These are cost and time problems, not permission problems.
Option 5: Accept a smaller or different building
If the envelope only fits 40m², a well designed 40m² one bedroom is a real granny flat that someone can live in comfortably. It is worth more than a 60m² design that never gets built.
What we would not recommend
Do not try to argue with a certifier. A certifier assessing a complying development application has no discretion. That is the entire design of the pathway. If your proposal misses a standard, the certifier cannot approve it regardless of how reasonable the variation seems. The place where discretion exists is council, through a DA.
Do not build first and seek approval later. Unapproved building work creates problems with insurance, with sale of the property, and with council enforcement, and it can be ordered removed.
Frequently asked questions
Is a DA likely to be refused?
Not automatically. Councils assess secondary dwellings regularly and a well prepared application for a modest granny flat on a block that misses the checklist narrowly is a normal thing to lodge. It is discretionary, so it is not guaranteed, but it is far from a long shot.
How much more does a DA cost than a CDC?
More, and the gap widens with complexity. Beyond the council application fee there are often additional consultant reports required, such as a statement of environmental effects, and sometimes arborist, flood or bush fire assessments. Ask for the DA path to be quoted separately so you can see the difference.
My block is 445m². Is that close enough?
No, not for complying development. The 450m² figure is a threshold and a certifier cannot approve below it. That is precisely the situation a DA is for.
Can I subdivide later to solve the lot size problem?
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.
Who tells me which standard I failed?
A builder or certifier working from your survey, title and planning certificate. If someone tells you your block does not qualify without naming the specific standard it missed, ask them which one, because the answer determines every option above.
Find out exactly where you stand
Knowing which standard your block misses is the difference between a redesign, a DA, and an internal conversion. It takes a proper look at your survey and planning certificate.
Check your block, or call BlueGum on 1300 060 651. BlueGum manages both CDC and DA approvals in-house.
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. Confirm your position with a certifier or your council.
