Our tree rating method scores a tree's condition and its likely lifespan, then sets how strongly a design should prioritise keeping it. It separates two questions reports often blur: how good the tree is as a tree, recorded as its arboricultural value, and how strongly it should be retained in its setting, recorded as its retention priority.
Why it exists and when we use it
Every assessment report rates the trees on a site, so the findings are consistent across a job and from one job to the next. The method is built so that a competent assessor, working from the same observations, reaches the same result. Each rating step is a defined lookup or a stated rule, so any figure in a report can be reproduced and, where it is challenged, traced back to the observation that produced it.
What it measures
Health and structure combine into a condition, where the worse of the two governs: a serious structural defect or active decline caps the rating, whatever the other attribute. Condition and useful life expectancy then combine into an arboricultural value, the tree judged as a tree, with nothing about its setting, ownership or any control over it.
Four contextual inputs sit alongside that value and feed a retention priority, each recorded separately so it can be examined and defended on its own: landscape contribution, habitat value, heritage and cultural significance, and existing site conflicts. They raise or lower the priority through a points model in which every weight is stated, so a challenge is to a specific number rather than to a judgement. Ownership and regulatory controls are kept out of both scores, because they govern what may lawfully be done to a tree, not how much the tree is worth.
What it is built on
Visual Tree Assessment from the ground (Mattheck and Breloer), with crown-condition bands aligned to the ICP Forests approach, and AS 4970:2025 for the root-zone calculations that the dimensions feed. The summed-criteria approach to retention follows established Australian practice (IACA SRIV and STARS). It is not a risk assessment, and assigns no likelihood of failure; where a risk rating is required, it is produced separately under a recognised method and reported on its own terms.
Want more detail? Get in touch to discuss your project and how we can help.