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Arboricultural Impact Assessment
The report a council asks for when your works reach a tree. It answers one question in a form a planner can assess: what does this proposal do to each tree, and can that tree survive it.
Fixed quote within one business day · agreed in writing before any work starts
When you need one
An AIA is triggered whenever a planning application involves works within the root zone of a tree that the council has an interest in protecting. In practice that means most infill development in the inner east, and almost anything on a site carrying a Vegetation Protection, Significant Landscape or Environmental Significance Overlay.
It also covers trees on neighbouring land. A tree over the fence whose root zone reaches into your site is squarely within scope, and leaving it out is one of the most common reasons a report gets sent back.
What is in it
- Every tree identified individually: species, age class, origin, dimensions including DSH, and a tree number that matches the plan
- Health and structure assessed, with the defects that matter to the recommendation named out loud, not flattened into a rating
- NRZ and SRZ calculated to AS 4970:2025, and the TPZ I have determined for the site stated separately
- Impact analysis against the actual proposal, tree by tree, with encroachment quantified as a proportion of NRZ area
- A clear retain or remove recommendation for each tree with the reasoning attached to it
- Tree protection measures specific enough for a council to write into a condition
- A plan showing tree locations and zones over the proposed works
- Photographs tied to the trees they show
On the 2025 standard
AS 4970 was revised in 2025 and the terminology moved. What used to be the calculated TPZ is now the Notional Root Zone. TPZ now means the area actually protected on site, which the project arborist sets. DBH became DSH, Diameter at Standard Height, still measured at 1.4 m.
Councils are working through the same transition at different speeds, so you will still receive checklists written in 2009 language. I report in current terminology and add one line explaining the equivalence the first time each term appears, which heads the confusion off instead of answering it six weeks later. The full rundown is here.
What drives the fee
Tree count is the main one, then access and whether usable plans exist. A five tree site with a current survey and a clear site plan is straightforward. Twenty trees across a battleaxe with no survey is not, and I will tell you at quote stage, not on the invoice.
If you have already had a preliminary assessment done by me, the site data carries across and the AIA is quoted accordingly. You should not pay twice to measure the same trees.
Common questions
How long does an arboricultural impact assessment take?
Site inspection is usually within a week of instruction, and residential inspections are typically completed within five business days. If you are up against a lodgement date, say so when you request the quote and I will tell you honestly whether it is achievable.
Does an AIA cover trees on the neighbour's property?
Yes, and it must. Any tree whose root zone extends into the works is within scope regardless of which title it stands on. Omitting neighbouring trees is one of the most common causes of a request for further information.
What qualification does the council require?
Most Victorian councils require a minimum of AQF Level 5, the Diploma of Arboriculture. A report from an author below that level can be refused on qualification grounds alone, no matter how sound the content is.
Can you amend the report if the design changes?
Yes. Where the tree data is already collected, an amended impact assessment against a revised plan is quoted as a variation, at a fraction of the original.
Other services
Tree Removal Report
ResidentialClause 52.37 Canopy Tree Report
Residential · PlanningPreliminary Tree Assessment
Before you designTree Protection Management Plan
DevelopmentRoot & Infrastructure Investigation
InvestigationArboricultural Supervision
On siteConstruction Monitoring
On siteTree Risk Assessment
TRAQ qualifiedTree Protection Zone Advice
Written adviceSend me the plans and I will send you a number.
Fixed fee, quoted in writing within one business day, scope written down. If it turns out you do not need this report, I will tell you that instead.