Home/ Granny flats

Secondary dwellings · Northern Beaches

A granny flat is a small build
with a full-size approval.

Two pathways, two very different timelines, and one decision that has to be made correctly at the start. We work out which one your lot qualifies for, then prepare the documentation either way.

The fork in the road

CDC or DA. Get this wrong
and you lose months.

A secondary dwelling — the planning term for a granny flat — is a self-contained dwelling within, attached to, or separate from the main house on the same lot. Under the State Environmental Planning Policy (Housing) 2021 there are two ways to get one approved, and they are not interchangeable.

Complying Development

Faster · If you qualify

A Complying Development Certificate combines planning and construction approval into one. No council assessment, no neighbour notification, dramatically shorter — but every standard has to be met, with no discretion available.

  • Lot generally must be at least 450m²
  • Floor area capped under the Housing SEPP
  • Setbacks, height and site coverage all prescribed
  • Fails on any single standard — no partial credit
Check whether your lot qualifies

Development Application

Slower · Always available

Council assesses the proposal on its merits. Slower and more expensive, but it's the pathway for lots under 450m², unusual sites, and designs that step outside the code for a good reason.

  • No minimum lot size bar under the state policy
  • Merit assessment — variations can be argued
  • Neighbour notification applies
  • Then still needs a CC before you build
See what happens after DA approval

The rules people get caught by

Four things worth knowing
before you draw anything.

  1. The floor area calculation changed. This is the big one. The way floor area is measured for the complying development pathway now takes in the principal dwelling, the secondary dwelling, and any attached carport, garage, balcony, deck, patio, pergola, terrace or verandah. Plenty of designs drawn to the old understanding no longer fit.
  2. One principal dwelling, one secondary dwelling. Per lot. If you're picturing two granny flats, or a granny flat plus a dual occupancy, that's a different application and a different conversation.
  3. You cannot subdivide it off. A lot with a secondary dwelling on it can't then be subdivided to sell the granny flat separately. If separate title is the actual goal, a secondary dwelling is the wrong instrument — look at dual occupancy and subdivision instead.
  4. The state policy is a floor, not a ceiling. Northern Beaches Council's own local environmental plan and development control plan can apply additional controls. Checking one and not the other is how people design something that satisfies the state policy and still gets knocked back.

A note on the rules

Planning controls change, and your council's local environmental plan can apply its own standards on top of the state policy. Everything on this page is general information current at the time of writing — we'll confirm what applies to your specific lot as part of your free assessment. We prepare documentation; we're not a certifier, and this isn't planning or legal advice.

What we prepare

The granny flat documentation
package, item by item.

Which of these apply depends on your pathway and your site. Your free assessment tells you which list is yours.

  • Pathway assessment — CDC eligibility against every applicable standard
  • Lot analysis: area, dimensions, existing floor area, site coverage
  • Architectural set coordinated to the approval pathway
  • BASIX certificate and evidence of committed measures
  • Structural engineering drawings and certification
  • Stormwater and drainage design
  • Sediment and erosion control plan
  • Waste management plan
  • Bushfire, flood or acoustic assessment where the site requires it
  • Arborist report where trees are affected
  • Sydney Water tap-in and building plan approval
  • Existing dwelling compliance evidence
  • NSW Planning Portal lodgement — CDC or CC
  • Principal Certifier appointment and Notice of Commencement
  • Critical stage inspection tracking through construction
  • Occupation Certificate package at completion

Common questions

What Northern Beaches owners
ask us first.

How big can a granny flat be?

The Housing SEPP caps the floor area for the complying development pathway — 60m² is the figure most people know, but the important detail is that the calculation now includes the principal dwelling and attached structures like carports, garages, decks and verandahs. That change catches a lot of designs. We check the current standard against your actual lot rather than working from a rule of thumb.

Can I put one on any block?

For the complying development pathway your lot generally needs to be at least 450m², and the property has to be in a zone where secondary dwellings are permitted — typically the residential zones. Below 450m² the CDC route closes but a DA is still open. Send us the address and we'll check the zoning and lot size for you.

Can I rent it out?

Secondary dwellings approved under the Housing SEPP can generally be rented separately from the main house — that's a large part of why the policy exists. Confirm the position for your specific approval, and check any conditions attached to it, before you commit to a rental income figure.

Can I sell it separately later?

No. A lot with a secondary dwelling on it can't be subdivided to create a separate title for the granny flat. If separate titles are the goal, you're looking at a dual occupancy with subdivision — a different approval, a different cost, and a different conversation worth having before you build anything.

Do I still need a CC if I go the CDC route?

No — a Complying Development Certificate covers both the planning approval and the construction approval, which is the main reason it's faster. You still need a Principal Certifier appointed, notice given before work starts, critical stage inspections during construction, and an Occupation Certificate at the end.

How long does the whole thing take?

The certificate itself is rarely the slow part. Assembling the documentation is — engineering, BASIX, stormwater, any site-specific reports. Projects that arrive with a survey and a design already done move quickly. Starting from a bare address takes longer, and we'll give you an honest timeline rather than an optimistic one.

Before you decide it can wait

What is the delay actually costing you?

Interest, rent, storage and holding costs keep running whether or not anything is happening on site. Move the sliders — the number updates as you go. Nothing is sent anywhere; it all runs in your browser.

Open the full calculator

Cost of the delay

$21,200

Every week it drags on $2,650

$1.2M
$1,150
8 weeks
Interest at 6.5% p.a.
Estimate only — not financial advice.
Full calculator →

Free assessment

Send us your address. We'll tell you
which pathway your lot is on.

Free, no obligation. We check lot size, zoning and the current standards, then give you a written document list for whichever pathway applies.

Get My Free Assessment

Or email hello@approvalhub.au with the property address — or call 0422 299 555