TRAQ Level 2 vs Level 3: which tree risk assessment do you need?

A Level 2 (basic) tree risk assessment is a full walk-around inspection with simple tools, and it's enough for most trees. A Level 3 (advanced) assessment brings in specialized equipment, such as a resistance drill or sonic tomography, to measure what you can't see from outside. You usually only need one when a Level 2 turns up a concern it can't answer.

What is TRAQ?

TRAQ stands for Tree Risk Assessment Qualification. It's a credential from the International Society of Arboriculture (ISA). Arborists who hold it are trained to assess tree risk the same way, step by step. Candidates take a two-day course and then pass written and field assessments. ISA requires holders to retrain and retest every seven years.

The method comes from ISA's Best Management Practices for tree risk assessment, which set out three levels. The arborist and client should agree on the level before work starts.

What are the three levels of tree risk assessment?

Level 1: Limited visual

A quick look from a walk-by, a drive-by or even the air for obvious problems like dead trees, broken branches or large cavities. It's meant for screening lots of trees at once, such as along roads or power lines. A Level 1 may not include recommendations for reducing risk. Oakstead offers all three levels, so a Level 1 screening of many trees (for example on a large property or strata) can show which ones need a closer Level 2 or Level 3 look. Oakstead's Level 1 assessment is $425 (plus GST) for a single tree; for several trees we quote per site.

Level 2: Basic

The arborist walks all the way around the tree and inspects the trunk, crown, root area and surroundings. Simple tools like binoculars, a mallet and a probe may be used. Then the arborist works through what they found and lists ways to reduce the risk. University of Florida Extension notes this is the level most arborists use for private clients.

Level 3: Advanced

A deeper look at one specific part of a tree, a defect, a target or a site condition. It takes longer and costs more, so it's normally saved for important trees or for questions a Level 2 can't settle.

Level 1 vs Level 2 vs Level 3 at a glance

When is a Level 2 enough?

For most residential trees, a Level 2 gives you a clear answer and shows the reasoning behind it. It's a good fit when:

• You want to know if a tree near your house, driveway or play area is a concern.
• You're buying or selling and want a documented view of the trees.
• A neighbour has raised a worry and you want a professional opinion.
• You need a baseline before planning work, pruning or a permit application.

The ISA basic assessment form asks the arborist to mark the data as either "final" or "preliminary." Final means the Level 2 is your answer. Preliminary means the arborist will recommend the kind of advanced assessment that would fill the gap.

When is a Level 3 warranted?

A Level 3 makes sense when the stakes are high or the main question is hidden from view. We see it most often in these cases:

• You suspect internal decay. Fungal growth, cavities, old wounds or a hollow sound when tapped may point to rot that a visual check can't measure.
• The tree is high value: a large heritage tree, a significant tree under a bylaw, or one that would be costly to lose.
• It's a high-target tree, standing over a house, a busy path, a parking area or a building where people gather.
• A strata council wants detailed evidence before deciding to keep, monitor or remove a large tree on common property. See our condo and strata page.
• An insurer or lender wants more than a visual opinion. Ask them what documentation they need before you book.

What tools does a Level 3 use?

• Resistance drill (often called a resistograph): A very thin needle is drilled into the wood and the resistance is recorded along its path. Soft or hollow zones show up as drops in resistance. University of Florida Extension describes it as one tool for measuring internal decay and notes it isn't required for every assessment.
• Sonic tomography: Sensors are placed around the trunk and sound waves are timed as they pass through the wood. Sound travels more slowly through decayed wood, so the software can build a picture of a cross-section. Cracks can sometimes make decay look larger than it is, so the results need an experienced eye.
• Other advanced methods: Aerial crown inspection, digging to inspect roots below ground, measuring changes over time such as lean, and load or pull testing.

Oakstead's Level 3 assessments use resistograph and sonic tomography testing.

What does a tree risk assessment report tell you?

A TRAQ-based report splits risk into three parts and then combines them into a rating.

The report also lists mitigation options, such as pruning, cabling, moving a target, monitoring or removal, along with the residual risk expected after each option. It should say when to reassess the tree and note anything that limited the inspection, such as poor visibility or a buried root collar.

Oakstead is consulting only. If your report recommends pruning or removal, we refer the work to vetted local partners and take no referral fees, so our recommendations aren't tied to selling tree work.

Not sure which level you need? Start with a tree risk assessment or request a consultation. Our ISA Certified, TRAQ-qualified arborist will recommend the right level. Full rates are on our pricing page.