Fernline 03 8 min read Guide
Council approvals for decks, walls and tree work
The Northern Beaches rules in plain language: exempt, CDC and DA paths for decks, retaining walls and tree removal, and when engineering comes into it.
Short answer: on the Beaches, most decks, walls over 600mm, and big trees need a formal OK from Council. The path is exempt, CDC or DA, in that order of pain.
Exempt, CDC or DA: which one applies
There are three paths. The path you land on turns on size, setbacks, and what overlays sit on your block.
- Exempt: no fee, no form, build to the State Code. Small decks (under 25 sqm, under 1m high), low walls, small pergolas.
- CDC: a private certifier signs off in about 20 working days, against a clear rulebook. Bigger structures that still fit the rules.
- DA: Council judges it case by case, 8 to 16 weeks. Anything that needs human review.
We scope the path at the design visit. No surprise mid-build.
Three things the Beaches makes harder
Three local rules catch homeowners out:
- Coastal hazard line: blocks east of it carry tighter setbacks and footing rules
- Bushfire-prone land: forces a BAL report and changes the deck timber you may use
- Tree and vegetation policy: most trees are kept, even ones you planted
We pull all three at the design visit. We design with the rules, not against them.
What approvals add to time and cost
- Exempt: zero weeks, zero fees
- CDC: 2 to 4 weeks plus drawings and engineering ($1,800 to $4,500)
- DA: 8 to 16 weeks plus the same paper and a Council fee ($1,500 to $3,500)
- Tree removal permit: 3 to 6 weeks for kept trees
Knowing the path before you book the build keeps the timeline honest. Book a design visit and we will scope the OKs up front.
Common questions
Do I need approval for a backyard deck on the Northern Beaches?
Often, yes. Decks under 25 sqm, under 1 metre off the ground and with prescribed setbacks can sit as exempt development under the State Code. Anything bigger, higher or closer to a boundary goes CDC (complying development) through a private certifier, or DA through Council. Coastal hazard, heritage and bushfire overlays change the answer. We scope which applies at the design visit and put it on the proposal in writing.
When does a retaining wall need engineering?
Walls over 600mm in NSW require certified structural design, and Council usually wants engineering details with the application. We engage a structural engineer at the design stage so the wall, the footings and the drainage are designed once and approved once, not redesigned mid-build because Council asked for it.
Can I just remove a tree on my own property?
Northern Beaches Council protects most trees over 5 metres tall or 3 metres canopy under the Tree and Vegetation Vegetation Management policy. You need a Permit to Prune or Remove, unless the species is on the exempt list. Removing a protected tree without one risks fines into five figures. We submit the permit as part of the design phase.