Dual occupancy in a Ku-ring-gai garden suburb
Ku-ring-gai sold itself as a garden suburb for a reason. West Pymble, Gordon and St Ives are streets of one house, a deep front setback, and a rear garden that could hold a tall tree. That pattern is why Council spent 2025 writing dual-occupancy controls around canopy and deep soil, and why the State Low and Mid-Rise map now sits over the same streets.
DC’s work here is the leftover ground: the strip that used to be one backyard and is now two courtyards, a dividing fence, a second driveway and a condition that says plant a 200 litre tree. This post is how that job actually runs.
Not planning advice. Check Ku-ring-gai’s map, KLEP 2015, DCP Part 5 and a duty planner for the lot.
Two rule books on the same street
Council’s dual occupancy bookAfter consultation in 2025, Council locked a 1,015 m² minimum parent lot into its local controls. The logic is blunt: smaller lots cannot hold the tall trees that make the suburb. Testing was done on lots between 1,015 and 1,250 m² because that is where most eligible blocks sit.
The State bookInside a mapped low and mid-rise housing area — roughly 800 m walk of Gordon, Pymble, Wahroonga, Turramurra, Killara, Lindfield and Roseville stations, and St Ives Shopping Village — a dual occupancy can use the Housing SEPP figures if every SEPP standard is met: 450 m², 12 m width, 0.65:1 FSR, 9.5 m height. If those standards are not all met, you fall back to Council’s 1,015 m². Complying-development dual occs in Ku-ring-gai still need 1,015 m².
West Pymble as a neighbourhood centre was not named as an LMR station in the same way Gordon and St Ives Village were. Plenty of West Pymble lots still sit near Pymble station’s 800 m walk, or next to Lane Cove National Park, or on bushfire-prone land. The map for the address is the first drawing, not the suburb name.
What is carved outHeritage items, TOD precincts and bushfire-prone land are treated differently. A family house on the high side of St Ives or the park edge at West Pymble may be in the LMR conversation and still be a bushfire assessment, not a clean dual-occ.
The Land and Environment Court is already seeing Ku-ring-gai flat buildings and replacement dwellings with landscape and arborist conditions written into the consent — Shinfield Avenue, St Ives is one example from 2026. Dual occs will follow the same pattern: the architecture gets approved when the landscape plan can be enforced.
The numbers that eat the backyard
Ku-ring-gai’s dual-occupancy DCP is written for a garden, not a paved court.
Landscaped areaThe parent lot must provide landscaped area equal to 50% of the lot minus 100 m². That total is split equally between the two dwellings. Beds count only if they are at least 1.5 m wide. A sliver along a side path does not count.
On a 1,015 m² lot that is about 408 m² of landscape, 204 m² per dwelling.
Deep soilAt least 30% of each dwelling site as deep soil, minimum dimension 2 m, capable of holding a tall tree. Deep soil is ground. A planter on a garage lid is not 30%.
Trees, soil area and soil volume
Tree | Height | Spread | Min. soil area | Min. soil volume |
Medium | 8–12 m | 4–8 m | 6 × 6 m | 35 m³ |
Small | 5–8 m | under 4 m | 3.5 × 3.5 m | 9 m³ |
A 200 litre tree is not a gesture. It is the smallest stock that has a chance of becoming the medium tree the table describes in a living generation. Conditions on Ku-ring-gai consents regularly name pot size because a 45 litre stick in a 1 m bed will not make the canopy number.
If the lot is also inside an LMR area, Council must consider the State Tree Canopy Guide as well: on a lot over 600 m² that is 25% canopy and 25% deep soil, with a medium tree for every 225 m². The stricter of the two documents is the one the landscape plan has to satisfy.
Built-upon areaThe DCP also caps how much of the lot can be building, driveway and paving. Two garages and two turning bays are often what blows the landscape percentage, not the second kitchen.
What a 1,015 m² garden suburb lot looks like after a dual occ
One house, a long rear garden, a Sydney blue gum or a turpentine near the back fence, street trees in a wide verge.
After:
two dwellings at up to 9.5 m
a side or central driveway
a new dividing fence, often masonry, with a footing
two private courtyards where there was one lawn
the existing tree either retained inside a Tree Protection Zone or replaced with two smaller trees that have not yet grown
If the existing tree stays, AS 4970 decides the courtyard. The structural root zone cannot take a strip footing. The protection zone cannot take a compacted driveway. Pier-and-beam, suspended paving and hand excavation are how the tree and the second house coexist. If they cannot, the arborist report has to say so in words Council will accept — and the 200 litre replacements have to be shown in real soil, not in the hatched “future planting” that never gets built.
On the park and ridge edges, add fire. An asset protection zone wants canopy off the roof, space between crowns, and low ground fuel. That is the opposite instinct to “plant the leftover courtyard as a forest.” The planting plan has to do both: screen the new first-floor window, and not build a wick to the eaves.
How to plant the leftover courtyard so it is still a garden
Treat each dwelling’s 204 m² as a courtyard with a job, not as leftover dirt.
Keep one real tree per dwelling.A medium tree in a 6 × 6 m deep-soil pad, 35 m³ of uncompacted soil, drained, not sitting on a tank lid. Species that belong on shale or sandstone in Ku-ring-gai — not a palm in a pot against the wall. If the original tree can stay, design the house around it. That single decision does more for the street than any condition.
Screen the new boundary.The first-floor window of dwelling two will look into dwelling one’s courtyard. A hedge or a layered screen on the dividing line is amenity, not decoration. Leave the footing of an 1800 mm masonry fence outside the neighbour’s structural roots. That argument is the same one DC runs in the Inner West; Ku-ring-gai just has bigger trees.
Do not pave to the fence.Every extra square metre of driveway is landscaped area you have to find somewhere else. Permeable paving on the parking bay helps the OSD drawing and keeps a little water in the soil the tree needs.
Connect to the verge and the gully.The DCP asks for green corridors where the lot adjoins bush or a landscaped neighbour. A planted side setback that lines up with the street tree and the rear canopy is how a dual occ still reads as Ku-ring-gai from the footpath.
West Pymble and the park edge.Sheldon Forest and Lane Cove National Park are not a backdrop. Critically endangered Blue Gum High Forest and Sydney Turpentine Ironbark Forest sit on private lots as well as in the reserve. A dual occ that clears the rear slope for a second lawn is a biodiversity problem, not only a canopy problem.
How to light it without turning it into a driveway
Two dwellings means two paths, two doors, two bins. The default is a bright flood on a sensor. That lights the neighbour’s bedroom and does nothing for the tree.
DC’s rule on these lots is the same as on an Inner West terrace, with more height in the canopy:
Warm white, 2700–3000K.
Path and step lights on one circuit — Bob, Spectrum, Horizon, Cluster Mini.
One or two spike uplights on the retained tree, aimed after dark, on a second circuit you can switch off. Firefly or Lotus for a small canopy; Willow only if the tree is actually large.
No flood across the dividing fence.
24V drivers sized with spare capacity, cable in the bed before the 200 litre stock goes in.
Aim so the beam dies in the foliage, not in the first-floor glass next door.
If the lot is in an APZ, keep ground fuel and mulch off the wall, and do not use the lighting design as an excuse to strip the understorey and then blast the bare dirt with a 36W flood.
What DC puts in the Ku-ring-gai pack
Confirm LMR / local housing area, TOD, heritage item, bushfire map and 10/50 for the address.
Survey the existing trees and calculate TPZ and SRZ before the second garage is drawn.
Test the DCP maths: 50% minus 100 m² landscape, 30% deep soil, soil volumes for the trees named on the plan.
If LMR applies, overlay the State canopy guide and meet the tighter figure.
Draw two courtyards that can be used, not two leftover triangles.
Write the lighting as part of the landscape plan so the trench is in before planting.
Lodge a plan Council can condition — species, pot size, soil volume, protection fencing — not a mood image.
The family house on a Gordon or St Ives street can become two dwellings. The garden suburb only survives if the leftover ground is still specified as a garden: real soil, a real tree, a fence that does not kill the roots, and light that lets you walk to the door without washing the canopy and the neighbour in the same beam.
Designing the second courtyard on a Ku-ring-gai lot?DC works in West Pymble, Gordon and St Ives as well as the Inner West and the harbour suburbs around Vaucluse. Bring the tree survey to the first meeting, not the las
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