If trees are present on or adjacent to your development site, there’s a good chance your council will require an Arboricultural Impact Assessment as part of your planning application. But not every project triggers the requirement — and understanding when you need one can save you time, money, and unnecessary delays.
What is an Arboricultural Impact Assessment?
An Arboricultural Impact Assessment is a report that analyses the potential impacts a proposed development may have on retained trees. It builds on the findings of a Preliminary Tree Assessment and evaluates how the proposed works — footings, excavation, demolition, construction access, and drainage — will interact with the Tree Protection Zones of trees on and adjacent to the site.
The AIA assesses:
- The degree of encroachment into Tree Protection Zones
- The likely impact of proposed works on tree health, structure, and longevity
- Whether retained trees can realistically survive the proposed construction
- Recommendations to modify the design, construction methodology, or tree management to minimise impacts
- Trees that may require removal as a result of the proposed works, and the consent pathway for doing so
When is an AIA required?
An AIA is generally required when a development application proposes works that will encroach into the Tree Protection Zone of one or more significant trees. This includes:
New builds and extensions where the proposed footprint, excavation, or services encroach into the TPZ of trees on or adjacent to the site.
Subdivisions where new lot boundaries, access ways, or infrastructure will affect existing trees.
Demolition works where the removal of existing structures may impact tree root zones or require machinery access through a TPZ.
Alterations and additions where proposed changes to drainage, landscaping, or site levels affect the growing environment of retained trees.
In Victoria, most councils will specify whether an AIA is required as part of their pre-application advice or planning permit conditions. Where significant trees are present and proposed works are in close proximity, an AIA is almost always expected.
How does an AIA differ from a PTA?
The Preliminary Tree Assessment identifies what trees are on site and establishes their protection zones. The Arboricultural Impact Assessment takes the next step — it puts the proposed development plan over those protection zones and assesses what happens when the two intersect.
In straightforward terms: the PTA tells you what you’re working with. The AIA tells you what your design will do to it — and what needs to change.
Why getting the AIA right matters
A well-prepared AIA does more than satisfy a council condition. It gives the design team a clear picture of where the real constraints are, enables informed decisions about design modifications early in the process, and identifies the most cost-effective path to retaining significant trees without compromising the development outcome.
An AIA prepared by an experienced arborist can also identify opportunities — modified footing systems, alternative access routes, or construction methodologies — that allow development to proceed without the tree loss that a less thorough assessment might have recommended.
Who should prepare it?
An AIA should be prepared by an AQF5 qualified arborist with specific experience in development reporting and a thorough understanding of AS4970-2025 — Protection of Trees on Development Sites. The report needs to withstand scrutiny from council planners, certifiers, and in some cases, VCAT.
At Shelterwood Consulting Arborist, every AIA is prepared by an AQF5 qualified, VALID Accredited arborist — giving you a report that is technically sound, council-compliant, and genuinely useful to your project team.
Need an Arboricultural Impact Assessment for your development? Get in touch with Shelterwood Consulting Arborist today. 📞 0417 526 476 | ✉️ shelterwoodarb@gmail.com