Tree inspection and risk assessment

After 2018 and 2022, the most common question in the Outaouais is no longer how much to remove a tree but whether it needs removing. It is a good question, because a large healthy tree is an asset and taking it down costs thousands, while a large defective tree beside a house is a five-figure risk. An inspection answers the question before the wind answers it for you.

Step one: the target. A risk assessment is not only about the tree. It is about what sits under the tree: the house, the driveway where children play, the shed, the street. A hollow tree at the back of a woodlot is not a risk. The same tree six metres from a bedroom is a different matter. The target, its value and how long it is occupied are established first.

Step two: the root collar and the roots. The inspection starts at ground level rather than in the crown. The assessor looks for roots severed by a trench or a paved driveway, a collar buried under fill or mulch, decay fungi at the base, soil lifting on one side, and recent lean. The great majority of trees that fall over completely in a storm have a root problem rather than a branch problem.

Step three: the trunk. Cavities, cankers, vertical cracks, included bark in a union, fungal fruiting bodies and insect traces. A mallet reveals hollow areas by sound. A large cavity is not automatically fatal: what matters is the thickness of sound wood remaining around it, and a trained arborist can estimate that ratio.

Step four: the crown. Dead wood and its diameter, broken hanging branches, unions with included bark that may split, asymmetry putting all the weight on one side, and signs of stress such as thin foliage or leaves smaller than normal. On an ash, the assessor looks for the borer's S-shaped galleries and D-shaped exit holes.

Step five: the report and the options. A good report does not only say remove or keep. It gives a risk level, a time frame, and the measures available: removing dead wood, selectively reducing an over-extended limb, bracing a split union, reducing the target by moving what sits beneath it, or removal. Bracing is a long-term maintenance commitment rather than something installed and forgotten.

How long it takes. A visual inspection of one tree is 30 to 60 minutes on site. A written report with photographs takes a few days. A more advanced assessment, using instruments to measure internal decay, takes longer and is mainly justified when the decision concerns a high-value tree or a significant target.

What it costs in 2026. Indicative ranges. An on-site visual inspection with a verbal opinion often runs $150 to $400, and many contractors credit it against the work if you hire them. A documented written report for an insurer, a neighbour or the City is more likely $400 to $1,200 depending on the number of trees and the level of detail. These are market orders of magnitude rather than figures from an official source, so always get a written quote.

What is particular to the Outaouais. Three things. The emerald ash borer has killed a large share of the region's ash, and a dead ash loses its strength quickly: it becomes dangerous to work on before it becomes dangerous to the house. Second, the 2018 tornado and the 2022 derecho left behind trees that look normal but carry split unions, broken roots and wounds that have closed over decay. That is the main reason for an inspection here. Third, the large wooded lots in Aylmer and Buckingham hold trees that grew up in a stand and are suddenly isolated when neighbouring trees come down: a tree used to being sheltered becomes far more vulnerable to wind within a single season.

Who is qualified to assess a tree. This is where certification matters most. The SIAQ administers the ISA Certified Arborist credential in Quebec, which requires three consecutive years of experience or recognised post-secondary training, a written examination of 200 multiple-choice questions with a 76 per cent pass mark, and maintenance through 30 continuing education credits over three years, with renewal not automatic (SIAQ, about certification). There is also the TRAQ qualification, devoted specifically to tree risk assessment. Check the name in the SIAQ professional directory. And since 8 June 2026, any worker carrying out the recommended work must hold the arboriculture qualification certificate (APSAM, report au 8 juin 2026 (RSST art. 312.103)).

What to ask before you hire. Are you an ISA Certified Arborist, and do you hold the TRAQ qualification. May I check your name in the SIAQ directory. Is the inspection charged, and is it credited if I give you the work. Will I receive a written report with photographs. Does the report set out options other than removal. And is there a conflict of interest, meaning: is the person recommending removal the person who will invoice for it.