Tree removal with a new house DA in Hornsby: LEP, DCP, arborist rules

In Hornsby Shire, trees you want to remove for a new house are assessed inside the development application, not through a separate tree permit. The council’s tree and vegetation controls sit in Section 1.2.6 of Hornsby Development Control Plan 2024 (which replaced Hornsby DCP 2013), made under Chapter 2 of State Environmental Planning Policy (Biodiversity and Conservation) 2021, and they work alongside the biodiversity and heritage clauses of Hornsby Local Environmental Plan 2013. If any tree stands within 10 metres of your proposed works, the council’s DA Submission Guideline asks for a tree survey and a tree protection plan prepared by a consulting arborist to AS 4970-2009. This article walks home owners through what the council checks, what an arborist report must contain and where new house DAs in Hornsby lose time on trees.

Who this is for: home owners planning a new house or knock-down rebuild on a treed block in Hornsby Shire, who want to know which trees can go, which reports the council expects and how to design around the trees that stay.

Which trees are protected in Hornsby Shire?

Section 1.2.6.1 of Hornsby DCP 2024 lists the “prescribed trees” that are protected. In short, every tree is protected except the species in Table 1.2.6-a (exempt species such as camphor laurel, privet, cocos palm, cotoneaster, umbrella tree and most fruit and nut trees). The DCP defines a tree as a long lived woody plant with the potential to grow higher than 3 metres, so a young tree of a protected species is still protected even if it is small today. All trees on a heritage item or inside a heritage conservation area are protected regardless of species, and Clause 5.10 of Hornsby LEP 2013 means heritage tree work needs consent, not just a permit.

The DCP also sets out exempt tree work in Section 1.2.6.1(d). No approval is needed to remove a tree under 3 metres in height that is not within native vegetation, a tree the council has agreed in writing is dead and not fauna habitat, a tree whose trunk base is within 3 metres of the foundation of an approved dwelling (garages and carports do not count), or to prune less than 10 per cent of the foliage once a year to AS 4373. Those exemptions do not apply on land mapped as “Biodiversity” on the LEP Terrestrial Biodiversity Map, on land with threatened species habitat, or where a consent condition requires the tree to be kept.

In practice: walk the block with the species list before you brief a designer. A block full of privet and camphor laurel is a different proposition to a block with three Sydney blue gums and a turpentine near the frontage.

Does a new house DA in Hornsby need a separate tree permit?

No, not for the trees affected by the works. Section 1.2.6.1(g) of Hornsby DCP 2024 states that where works to trees are required as part of other works that need development consent, the tree works are assessed as part of the development application. Table 1.2.6-b confirms that tree removal in a DA context is dealt with by the DA, while stand-alone removal on other land is a tree permit under Section 2.10 of the Biodiversity and Conservation SEPP. The council’s own trees web page says the same thing.

The state framework behind this is Chapter 2 of State Environmental Planning Policy (Biodiversity and Conservation) 2021. Clause 2.6 makes it an offence to clear vegetation declared by a DCP without a permit, Clause 2.9 lets the DCP declare which vegetation is covered by species, size or location, and Clause 2.10 lets the council issue permits. Clause 2.8 confirms clearing is only “permitted without consent” when it is not ancillary to other development. Once the clearing is ancillary to your new house, the DA is the approval.

The common mistake is lodging a tree permit application first, waiting for it, then lodging the DA. The council will generally decline to deal with the tree separately and the time is wasted. Put the trees in the DA drawings and the arborist report and lodge once.

What does Hornsby LEP 2013 add on biodiversity and heritage?

Clause 6.4 of Hornsby LEP 2013 applies to land identified as “Biodiversity” on the Terrestrial Biodiversity Map. Before determining a DA on that land the council must consider the impact on the condition and ecological value of the flora and fauna, the importance of the vegetation as habitat, fragmentation of biodiversity and habitat connectivity, and any avoidance or mitigation measures. Under subclause (4) consent cannot be granted unless the council is satisfied the development is designed, sited and managed to avoid significant adverse impact, or to minimise it where avoidance is not feasible, or to mitigate it where minimisation is not possible. That is the avoid, minimise, mitigate hierarchy, and your statement of environmental effects needs to address it in those terms.

Clause 5.10 (heritage conservation) means tree removal on a heritage item or in a heritage conservation area is a heritage matter as well as a tree matter, and the DCP’s Part 9 (Heritage) applies. Clause 6.14 (riparian land) and Clause 5.21 (flood planning) can also affect what you can clear near creeks. Check your Section 10.7 certificate for the biodiversity and heritage map layers before you commit to a design.

What does the arborist report need to contain?

Hornsby’s DA Submission Guideline (revised November 2025) lists a Tree Protection Plan as a required document for any application proposing works within 10 metres of an existing tree. The plan must identify each tree, show its tree protection zone (TPZ) and structural root zone (SRZ) calculated in accordance with AS 4970-2009 Protection of trees on development sites, and show the location of tree protection fencing. The guideline requires the plan, and the arboricultural assessment report that supports it, to be prepared by a consulting arborist with an Australian Qualifications Framework Level 5 qualification. Section 1.2.6.1(c) of the DCP repeats the AQF 5 requirement for a project and consulting arborist.

Section 1.2.6.1(j) explains how removal requests are assessed. Trees are evaluated for safe useful life expectancy using industry risk methods such as Tree Risk Assessment Qualification or Quantified Tree Risk Assessment, and an application for removal must demonstrate that removal is appropriate on that basis. Section 1.2.6.1(k) then requires AS 4970 to be applied to every tree that is retained. A good report therefore does three things: it lists every tree on and near the site with species, height, spread, diameter at breast height and condition; it gives a retention value and a recommendation for each tree; and it calculates the TPZ and SRZ for the trees to be retained and states whether the proposed footprint, driveway, stormwater line and cut or fill encroach on them.

Under AS 4970-2009 the TPZ radius is 12 times the trunk diameter measured at 1.4 metres above ground, with a minimum of 2 metres and a maximum of 15 metres, and encroachment of up to 10 per cent of the TPZ area is generally treated as minor if the SRZ is untouched. For comparison, Table 1.2.6-b of the DCP uses its own tree protection zone radii to decide when works near a tree need approval: 9 metres from a tree with a trunk diameter of 800 millimetres or more, 7 metres for a trunk between 400 and 800 millimetres, and 4 metres for a trunk of 400 millimetres or less. Both sets of numbers matter, because the DCP radius decides whether you need approval and the AS 4970 zone decides whether the tree will survive.

Controls versus a typical new house proposal

How the tree assessment fits into the DA, step by step

1. Obtain a Section 10.7(2) and (5) certificate and the LEP map layers, and confirm whether the land is mapped “Biodiversity”, heritage listed, in a heritage conservation area, bushfire prone or riparian.
2. Commission a boundary and detail survey that plots every tree on the site and every tree on neighbouring land or the verge whose canopy or TPZ reaches the site. The DA Submission Guideline expects species, diameter, spread and location on the tree survey plan.
3. Engage an AQF 5 consulting arborist before the designer fixes the footprint. Ask for a preliminary arboricultural assessment that identifies high retention value trees and their TPZ and SRZ.
4. Brief the designer to site the house, garage, driveway, stormwater absorption trench and cut or fill outside the SRZ of retained trees and, where possible, outside their TPZ. Pier and beam construction near roots is a standard solution the arborist can specify.
5. Prepare the tree protection plan and final arborist report to AS 4970-2009 for the trees to be retained, with removal justified for the rest using the risk and life expectancy methods in Section 1.2.6.1(j).
6. Write the statement of environmental effects so it addresses Clause 6.4 of the LEP where it applies, Section 1.2.6 and Section 1.3.1 of the DCP, and proposes replacement planting. The DCP’s landscape controls in Part 3 expect canopy to be maintained or enhanced.
7. Lodge the DA on the NSW Planning Portal with the tree documents uploaded under the council’s document naming format, then expect conditions requiring tree protection fencing before demolition and arborist sign-off at key stages.

Where new house DAs in Hornsby lose time on trees

The first pattern we see is a footprint drawn without an arborist. The report then arrives, finds a retained tree with a 9 metre TPZ under the proposed garage, and the council asks for a redesign in its request for further information. The second is treating the verge tree as somebody else’s problem. Council street trees are managed by the council, but their roots and TPZ extend into private land and a driveway crossing that severs them will be refused or heavily conditioned. The third is a tree removal justification that says “the tree is in the way”. Section 1.2.6.1(j) is explicit that removal is judged on risk, condition and life expectancy, so the arborist needs to give real reasons, and where the tree is healthy the application needs to show why the house cannot reasonably be placed elsewhere, particularly on land mapped “Biodiversity” where Clause 6.4 of the LEP requires avoidance first. Replacement planting also helps; the council expects canopy to be replaced, and a landscape plan with advanced native trees supports the case.

Definitions

Prescribed tree

A tree protected by Section 1.2.6 of Hornsby DCP 2024 under the Biodiversity and Conservation SEPP. In Hornsby this is every tree with the potential to exceed 3 metres in height, except listed exempt species, plus all trees on heritage items and in heritage conservation areas.

Tree protection zone (TPZ)

Under AS 4970-2009, the area around a tree set aside to protect its roots and crown, with a radius of 12 times the trunk diameter at breast height. The DCP also uses fixed radii of 4, 7 and 9 metres to decide when works near a tree need approval.

Structural root zone (SRZ)

The smaller zone close to the trunk that holds the roots needed for the tree to stay upright. AS 4970-2009 treats encroachment into the SRZ as a threat to the tree’s stability.

Consulting arborist (AQF 5)

An arborist holding the Australian Qualifications Framework Level 5 Diploma of Arboriculture, which Hornsby requires for arboricultural assessment reports and tree protection plans lodged with a DA.

Terrestrial Biodiversity Map

The map adopted by Hornsby LEP 2013 that identifies land to which Clause 6.4 applies. Development on that land must be shown to avoid, minimise or mitigate significant adverse biodiversity impacts.

Biodiversity offsets scheme threshold

The area of native vegetation clearing above which a council permit or DA is not enough and approval from the Native Vegetation Panel is required under Clause 2.6(2) of the Biodiversity and Conservation SEPP. On lots under 1 hectare the threshold is 0.25 hectares.

URBA prepares statements of environmental effects for new houses and knock-down rebuilds across the Hornsby Shire, coordinating the arborist, surveyor and designer so the tree protection plan and the site plan tell the same story before lodgement. See our statement of environmental effects service and our Sydney town planning page, or request a fee proposal for your site.