Tree Risk Assessments

A tree risk assessment is a structured evaluation of a tree's likelihood of failure and the potential consequences if it does fail. It follows the ISA's Tree Risk Assessment Qualification (TRAQ) methodology and produces a written report rating overall risk as low, moderate, high, or extreme. The report documents the tree's structural condition, defects identified, the target zone (what or who would be struck if the tree failed), and specific recommendations for mitigation.

Common situations include: an insurer requesting a formal evaluation before renewing coverage or processing a claim; a neighbour or legal counsel requiring independent documentation in a dispute; storm damage that leaves you uncertain about a tree's stability; a pre-purchase property inspection for a home with large or mature trees; estate planning or property due diligence; and municipality requests for a formal risk evaluation before issuing a removal permit for a tree without obvious decline.

A general arborist inspection assesses tree health and condition in broad terms. A tree risk assessment specifically quantifies the probability of failure, the probability of impact on a target, and the consequences of that impact, then combines these into an overall risk rating. The TRAQ methodology produces a standardized rating that insurers, lawyers, and municipalities recognize and accept. It is a more rigorous, defensible document than a general health report.

The ISA TRAQ framework rates risk as low, moderate, high, or extreme, based on three factors evaluated independently and then combined: likelihood of failure (structural condition, defects, root issues), likelihood of impact (whether a target is present and how often), and consequences of failure (what would be struck and how serious the outcome would be). Each factor is scored and the scores are combined into the final risk rating using the ISA matrix.

Most residential assessments covering one to three trees take 1–2 hours on site. The written report is typically delivered within 2–3 business days of the visit. Properties with many trees or complex situations may take longer. If you need the report urgently for legal proceedings or an insurance deadline, let us know when you contact us and we will do our best to accommodate.

These are distinct documents serving different audiences. A tree removal report (arborist report) supports a municipal permit application and documents why a tree qualifies for removal. A tree risk assessment quantifies the probability and consequences of failure using the ISA TRAQ methodology, producing a report intended for insurers, lawyers, or courts. Most standard permit applications need a removal report, not a risk assessment. However, some municipalities will request an accompanying risk assessment when a permit is contested or when the tree shows signs of structural failure. If you are unsure which applies, contact us and describe your situation.