Quick answer: In NSW, a home extension is approved through one of two pathways, a Complying Development Certificate (as fast as 20 days) or a full Development Application (around 70 days on average). Once approved, a Notice of Commencement and HBCF insurance are required before construction can legally begin.
Approval is the part of extending a home that causes the most anxiety, mostly because it’s the part homeowners have the least visibility into. Here’s how it actually works.
Two Approval Pathways
Development Application (DA): A formal request assessed by council on its merits, generally required for larger, more complex, or non-standard projects. According to the NSW Government, a DA takes around 70 days on average to determine.
Complying Development Certificate (CDC): A faster pathway, issued through a private certifier, for projects that meet pre-set planning and building standards. CDCs can be issued in as little as 20 days, but the trade-off is that a project must fully comply. If even one element falls outside the standard, it can’t proceed under a CDC and needs to go through a DA instead.
Which pathway suits your project depends on your block, your council’s local planning controls, and how far your design pushes beyond standard setbacks and heights, this is exactly why our design and planning stage happens before a proposal is finalised, not after.
Development Application vs Complying Development Certificate at a Glance
| Development Application | Complying Development Certificate | |
|---|---|---|
| Assessed by | Local council, on merit | Private certifier, against fixed standards |
| Typical timeframe | Around 70 days on average | As fast as 20 days |
| Best suited to | Larger, more complex, or non-standard designs | Designs that meet pre-set setback, height and materials standards |
| Flexibility | Allows for design variation and negotiation | No flexibility, any non-compliance means it can’t proceed under a CDC |
Notice of Commencement
Once your approval is in place and any pre-commencement conditions are met (such as HBCF insurance), your certifier issues a Notice of Commencement. There’s a short mandatory wait after this before work can legally start, and if your project is within 20 metres of a neighbouring dwelling, written notice must go to those neighbours in advance.
HBCF Insurance
For most residential building work over $20,000, NSW law requires Home Building Compensation Fund (HBCF) insurance, which protects you if your builder can’t complete the work due to insolvency, death, or disappearance. According to icare NSW, this cover currently caps at $340,000 per dwelling. This is issued as part of our standard process, ahead of your deposit, not an optional extra.
Who’s Involved in the Approval Process
Your builder, coordinating the overall proposal and sequencing.
A designer or architect, preparing the plans that go to your certifier or council.
A private certifier or council, assessing and issuing your approval pathway.
An insurer, providing HBCF cover once your policy is approved.
Each of these roles has a defined place in our process, which is exactly why steps 4, 5, 11 and 13 of our checklist exist as separate, sequenced steps rather than being bundled together.
How This Fits Into Our Process
Steps 4, 5, 11 and 13 of our renovation checklist cover site inspection, design and planning, HBCF insurance, and notice of commencement in order. We manage this process alongside your certifier so you’re not left interpreting planning jargon on your own. See our full range of services for how this applies across every project type.
Frequently Asked Questions
How do I know if my extension qualifies for a Complying Development Certificate? It depends on whether your design meets pre-set planning and building standards for setbacks, height and materials. This is assessed during the design and planning stage of your project.
What happens if my project doesn’t comply with CDC standards? It needs to go through a full Development Application instead, assessed by council on its merits rather than against a fixed checklist.
Is HBCF insurance the same as home and contents insurance? No. HBCF specifically protects you if your builder can’t complete the work due to insolvency, death or disappearance, it doesn’t replace your own home and contents policy.
Not sure which approval pathway your project needs? Get in touch and we’ll talk you through it.