Duffys Forest zoning & planning overlays
A planning-constraint profile of Duffys Forest
(Northern Beaches, NSW) - 5.24 km², mapped from live council and
state overlay data. This suburb is highly constrained on the overlays we could measure - no flood mapping covers this suburb, so this is not a suburb-wide verdict.
Profile updated 26 September 2026.
Suburb-wide figures; the free map shows which overlays touch your lot.
Constraint readout
5.24 km² - this suburb is highly constrained on the overlays we could measure - no flood mapping covers this suburb, so this is not a suburb-wide verdict.
Elevation hillshade with street names, clipped to Duffys Forest's boundary, with the bushfire and environmental overlays drawn on top. Magenta is where aircraft were observed in the sampled period, brightest below 3,000 ft. No flood layer is drawn because we hold no flood mapping for this area.
Nearby suburbs, nearest first
Aircraft noise and flight paths over Duffys Forest
Two different things, kept apart on purpose. The ANEF contour is the planning instrument - a forecast published per airport that planning schemes use to control noise-sensitive development. Observed overflight is what a sampled aircraft-tracking feed actually recorded over the suburb - where aircraft flew, how low and how often.
Observed overflight - sampled 4 Sep to 25 Sep 2026
typical observed square 2 a day
Night movements: observed, lowest 5,500 ft - night is sampled as often as day, but night traffic is light, so this is a floor and no rate can be put on it.
Traffic is sampled rather than watched continuously, so every figure is a floor: aircraft not captured between samples are not represented. Rates are per 500 m square - the busiest square in the suburb, not a count of flights over the suburb - and a square is only rated where enough traffic was seen to measure it. Altitudes are above mean sea level. Flight paths change with runway use, weather, season and airspace design. This is a record of observed traffic; it is not a noise contour and not a planning control.
Duffys Forest at a glance
How Duffys Forest is zoned
Buying in Duffys Forest? The zoning, flood and bushfire lines on the section 10.7 certificate attached to the contract are mapped controls - see our s10.7 certificate guide.
Across its 5.24 km², Duffys Forest is highly constrained by the planning overlays we hold. We hold no flood mapping covering this suburb, so no flood figure is shown - that is a gap in our data, not an all-clear. Of what is mapped, 73% is flagged bushfire-prone. There are 2 heritage-listed sites on record, and the dominant land-use zone is Primary Production Small Lots. The median lot measures about 20,140 m² across 186 parcels.
Who lives in Duffys Forest
Census 2021 figures published by the ABS for the Duffys Forest suburb boundary itself, not a wider region.
Socio-economic standing
ABS SEIFA 2021 ranks every Australian suburb. Decile 1 is the most disadvantaged tenth of the country, decile 10 the least.
Score 1153, and decile 10 within New South Wales. The national average is 1000.
Age profile
Share of Duffys Forest's 509 residents in each ABS age band.
Population trend, 2001 to 2025
Estimated resident population of Terrey Hills - Duffys Forest, the wider ABS statistical area containing Duffys Forest. There is no annual population series published at suburb level, so this describes the surrounding area rather than Duffys Forest itself.
3,789 in 2001 to 3,593 in 2025, down 5%.
Source: ABS Census 2021 and SEIFA 2021 (Suburbs and Localities), Regional Population (SA2), CC BY 4.0. Small counts are randomly adjusted by the ABS.
Duffys Forest data sources and coverage
“Not mapped” means we hold no source layer for this suburb - never an all-clear.
| Dataset | Coverage | Publisher |
|---|---|---|
| Flood mapping | Not mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Bushfire-prone mapping | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Zoning | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Heritage and environment | Mapped where published | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Aircraft noise contours (ANEF) | Not held | NSW Government spatial services, NSW ePlanning and published council flood studies, Defence |
| Observed flight paths | Observed | adsb.lol, under the Open Database License |
| Demographics | Available | Australian Bureau of Statistics (2021 Census and SEIFA) |
Profile last materially updated 26 September 2026. See the methodology and full source list. Source data changes over time and critical decisions should be checked with the responsible authority.
Check a specific Duffys Forest address
See exactly which overlays touch a single property - the interactive map is free. Need it on paper? A full planning PDF is just $9.
Aircraft have been seen below 3,000 ft over about 94% of Duffys Forest. The report's Aircraft Overflight page narrows that to the address itself: how many aircraft a day, how low, and at what heights.
Published flood models are held over parts of Duffys Forest. The free check tells you whether one reaches an address; where it does, a Flood Model Report is +$9 with the planning report.
Building or pricing a slab? The $119 geotechnical desktop report covers geology, soils, bores and an indicative AS 2870 site class for a Duffys Forest lot.
See what's in the $9 report →Duffys Forest planning - frequently asked
Is Duffys Forest flood-prone?
We don't yet hold flood mapping covering Duffys Forest, so this page can't say how much of the suburb is flood-affected - that is a gap in our data, not an indication that the suburb is free of flood risk. Northern Beaches is the authority to check for flood mapping in this area. Published flood models are held over parts of Duffys Forest; the free check on the Flood Model Report page says whether one reaches a given address.
Is Duffys Forest bushfire-prone?
Around 73% of Duffys Forest is mapped as bushfire-prone, compared with a Northern Beaches average of 47%.
Is Duffys Forest under a flight path?
Aircraft were observed below 3,000 ft over about 94% of Duffys Forest, and over about 100% at any altitude up to 10,000 ft, in the period sampled (4 Sep 2026 to 25 Sep 2026). The lowest measured aircraft was at 500 ft, with an average of 4,000 ft. At the busiest point in the suburb about 24 aircraft a day were recorded passing over one 500 m square. Traffic is sampled rather than watched continuously and flight paths change with runway use, weather and season; the ANEF contour is the planning instrument.
What is the zoning in Duffys Forest?
The dominant planning zone in Duffys Forest is Primary Production Small Lots, though the suburb also includes National Parks and Nature Reserves and Public Recreation.
Does Duffys Forest have heritage-listed places?
Duffys Forest has 2 heritage-listed places on record.
What is the typical lot size in Duffys Forest?
Across 186 surveyed parcels in Duffys Forest, the median lot size is about 20,140 m². There are also 2 registered easements mapped in the suburb.
Does Duffys Forest have a train station?
There is no train station inside Duffys Forest itself. The suburb is served by 41 bus stops.
What is the population of Duffys Forest?
At the 2021 Census Duffys Forest had 509 usual residents, with a median age of 43 and an average household size of 3.2 people. The wider Terrey Hills - Duffys Forest statistical area, which contains Duffys Forest, went from 3,789 people in 2001 to 3,593 in 2025, down 5%.
Is Duffys Forest an advantaged suburb?
On the ABS SEIFA 2021 index of relative socio-economic advantage and disadvantage (IRSAD), Duffys Forest scores 1153 and sits in decile 10 of 10 nationally and decile 10 within New South Wales (decile 1 is the most disadvantaged tenth, decile 10 the least).
What is the median household income in Duffys Forest?
Median household income in Duffys Forest was $4,250 a week at the 2021 Census, against $2,778 for the typical suburb in Northern Beaches. Median rent was $625 a week and the median mortgage repayment $6,134 a month.
Compare nearby suburbs
| Nearby suburb | Distance | Flood mapped | Bushfire-prone |
|---|---|---|---|
| Terrey Hills | 3.3 km | 0% | 69% |
| St Ives Chase Ku-Ring-Gai |
4.2 km | Not mapped | 75% |
| North Turramurra Ku-Ring-Gai |
4.3 km | <1% | 86% |
| Ku-Ring-Gai Chase | 4.7 km | <1% | 99% |
| Belrose | 5.7 km | 5% | 80% |
| Cottage Point | 6.0 km | 0% | 99% |
| Berowra Hornsby |
6.1 km | 0% | 87% |
| St Ives Ku-Ring-Gai |
6.2 km | 3% | 58% |
| North Wahroonga Ku-Ring-Gai |
6.3 km | 2% | 87% |
| Ingleside | 6.4 km | 7% | 96% |