Tree risk assessment
An arborist's professional judgment on how likely a tree is to fail, and what it could hit if it does.
What it is
A tree risk assessment looks at the tree's structure, decay, lean, roots and surroundings to decide how likely a failure is and how serious it would be. You get a recommendation: keep it, prune it, support it, monitor it or remove it.
Look for an arborist who holds the ISA Tree Risk Assessment Qualification, a specific training in judging whether a tree is dangerous. For trees with hidden decay, advanced tools like resistance drilling or sonic tomography can measure the inside of the trunk.
Signs you might need it
- A big tree over the house, driveway or play area that you're worried about
- Cracks, cavities, mushrooms or a new lean
- Damage after a storm
- Buying a property with large trees
- Your city or insurer asks for a professional opinion
Good to know
A quote from a tree company isn't the same as an independent risk assessment; a company that also sells the removal has a reason to recommend it. For a formal written opinion, see arborist reports.
Typical cost in Ontario
Before HST. Advanced testing such as resistance drilling adds roughly $200–$500 per tree. Written-report and testing prices lean on US sources.
What pushes the price up or down
- Level of assessment: a quick visual check, a basic assessment, or advanced testing
- Number and size of trees
- Whether a formal written report is needed
- Urgency (after a storm)
- The assessor's qualifications
Ways to spend less
- Have every tree you're worried about assessed in one visit
- Ask whether advanced testing is really needed before paying for it
- If you plan to remove a dead or dangerous tree, check whether one report can also serve your city's permit or exemption process
The basic inspection price is from Ontario; written-report and testing prices lean on US sources. Prices are typical ranges gathered from published Ontario price guides and company price pages in September 2026, before 13% HST. They’re a guide, not a quote: your price depends on your tree and your property. Get two or three written quotes, and check whether your city charges a permit fee.
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Related specializations
Sources for the prices on this page
- How Much Does Hiring An Arborist Cost in 2026? | Tree Doctors Inc. (Toronto, ON)
- Arborist Report Cost in Toronto: 2026 Pricing Guide - Loyal Tree (Toronto, ON)
- Arborist Report Cost: 2026 Prices by Type (US prices, in US dollars)
- Tree Risk Assessment: When You Need One & What It Costs (2026) (US prices, in US dollars)
- TreeInspection.com - Services and Fees (US prices, in US dollars)
- GTA Tree Permit Requirements by Municipality (2026) (GTA, ON)
- GTA Municipal Tree Preservation Requirements | BH Consulting Arborist (GTA, ON)