What's Inside a Tree Risk Assessment Report

Cover & Administrative Section

Every TRAQ report begins with a cover page that establishes the legal and professional record. It identifies the client (name and contact), the site address, the inspection date, and the stated scope of work — what the inspector was hired to do and what was explicitly outside the scope. The limiting conditions section is critical: it tells the reader what the inspector could not evaluate (e.g., trees behind locked fences, root zones under paving that couldn't be excavated). A signature block at the end includes the arborist's name, credentials, and ISA certification number, making the report a defensible professional document. For attorneys and insurers, this cover page is often the first — and sometimes only — thing reviewed before deposing the expert.

Tree #14 (coast live oak, 18" DBH): excluded from full crown assessment due to dense ivy coverage. Canopy die-back estimate based on visible terminal shoots only. Crown reduction pruning recommended pending ivy removal and re-inspection.

Site and Tree Inventory

The inventory section is the factual backbone of the report. Each tree is assigned a tag number corresponding to markers placed in the field, and its location is recorded either by GPS coordinates, a sketch, or both. Every tree receives a species identification (common and Latin name), followed by structural measurements: DBH (diameter at breast height, measured at 4.5 feet above grade), total height, crown spread, and a condition class (typically Good / Fair / Poor / Dead). This standardized data allows a property owner or attorney to sort and filter trees by any parameter — finding all Fair-condition oaks over 20" DBH, for instance — without re-reading narrative text. The inventory also records the target(s) each tree might affect, which becomes critical in Section 4.

Tree #7: Quercus agrifolia (coast live oak), DBH 24", height 42', crown spread 38', Condition: Fair. Lean: 8° toward northeast. Target: single-family residence entry driveway, 15' from trunk. Tag #7 placed on northeast face at 4.5' above grade.

Visual Assessment Findings

This is where the arborist's expertise is most visible — literally. A TRAQ Level 2 inspection examines the crown for dead branches, thinning, pest damage, and abnormal growth; the trunk for cavities, fungal bodies, borer activity, and mechanical damage; the root collar (the zone at the base of the trunk where it meets the soil) for tissue compression, girdling roots, and wood decay; the root zone for soil disturbance, shearing, or compaction; and the overall lean and structural architecture for asymmetric loading or prior failure points. The inspector documents findings photographically — ISA and ANSI standards govern what must be imaged and from what distance/angle. For a developer or property manager, this section answers the question: "What exactly did the inspector see, and why does it matter?" Every defect is linked to a potential failure mechanism.

Tree #22 (valley oak, 31" DBH): large cavity on south face at 8' height, extending 14" vertically, depth estimated >3" into sound wood. Adjacent bark pressure crease indicates long-standing mechanical stress. Fungal fruiting body (Ganoderma applanatus) observed at base — indicative of internal wood decay. Risk elevated despite superficially acceptable crown vigor.

Target Zone Analysis

Risk is not just about the tree — it's about what the tree can hit. The target zone is the area that would be affected if the identified part of the tree failed and fell. TRAQ classifies this by the occupancy and use of the area: a tree directly over a frequently-used driveway or playground carries more risk than the same tree over open lawn, because the likelihood of impact is higher. The report defines the target for each tree or group, noting whether it's a structure (house, shed), a travel path (driveway, sidewalk), a recreation area, or a managed landscape. This is often the most misunderstood section by non-experts — they assume a "large tree" always means high risk, when in fact a 60-foot oak over open grass may warrant a Low rating precisely because the target is unoccupied.

Tree #11 (black walnut, 19" DBH): target zone includes the primary single-vehicle driveway (estimated vehicle passage 2–4 times daily) and the front entry walkway. Occupancy class: Moderate-frequency. Same species and DBH over the adjacent wildflower meadow would register Low due to negligible target occupancy.

The Risk Matrix

TRAQ's four-step methodology converts observations into a rating. Three factors are combined: Likelihood of Failure (how probable is it that this part of the tree will fail within the inspection interval — Unlikely / Possible / Likely / Imminent); Likelihood of Impact (will the failing part actually strike the target — Unlikely / Possible / Likely); and Consequences (what happens if impact occurs — negligible / minor / significant / severe). Multiply these three ratings and you get a Risk Rating: Low, Moderate, High, or Extreme. The report presents this as a matrix and applies it to each tree or identified target. For attorneys, the matrix provides the analytical framework — not just a conclusion — making the rating defensible in cross-examination. For property owners, it explains why one tree gets a "High" while a larger one nearby gets "Moderate."

The matrix below shows how the three TRAQ factors combine into a Risk Rating. Each cell's color corresponds to the resulting rating.

Likelihood of Failure →		Unlikely	Possible	Likely	Imminent
Likelihood of Impact ↑
	Consequences: Significant Likelihood of Impact: Likely	Moderate	High	High	Extreme
	Consequences: Minor Likelihood of Impact: Likely	Low	Moderate	High	Extreme
Consequences: Negligible Likelihood of Impact: Likely	Low	Low	Moderate	High
Consequences: Severe Likelihood of Impact: Likely	High	High	Extreme	Extreme
Consequences: Significant Likelihood of Impact: Possible	Low	Moderate	High	Extreme
Consequences: Minor Likelihood of Impact: Possible	Low	Low	Moderate	High
Consequences: Significant Likelihood of Impact: Unlikely	Low	Low	Moderate	High

Low Moderate High Extreme

Tree #31 (coast live oak, 22" DBH): Failure likelihood: Possible (decay column in lower trunk, 40% cross-section affected). Likelihood of impact: Likely (primary target is the occupied carport directly beneath). Consequences: Significant (structural damage to vehicle, potential occupant injury). Risk Rating: High. Mitigation required within 90 days.

Mitigation Options

The arborist's job is to identify options, not to sell work. Mitigation options are presented as independent choices, ranked by effectiveness: reduction or removal of the failing part (crown reduction, target limb removal); cabling or bracing to add mechanical support to a structurally weak union; target removal (relocating a playset or patio from under the tree's fall zone); health treatments (fertilization, pest management — though these do not reduce structural risk); increased monitoring intervals (re-inspection every 6, 12, or 24 months); or removal when no viable mitigation exists. The report makes clear that these are independent recommendations and that the client decides. This section is what separates an independent consulting arborist from a tree company — no work is being sold, no crew is being dispatched.

Tree #31 (High rating): Two viable paths presented. Option A — 30% crown reduction to reduce sail area and remove two target branches, estimated cost $800–$1,200 by licensed contractor (not performed by this firm). Option B — target removal: relocate parked vehicle to street parking. If Option B is chosen, re-inspection interval extended from 90 days to 12 months. Option A preferred; Option B acceptable given budget constraints.

Limitations and Re-Inspection

No inspection is complete without acknowledging what wasn't examined and why. Standard limiting conditions include: trees not accessible (locked gate, dense vegetation), root zones covered by paving or structures that cannot be excavated, conditions that existed at the time of inspection and may have changed since, and inspections that do not include internal wood decay testing (resistograph, sonic tomography) unless specifically contracted. The re-inspection section recommends a cadence based on risk rating: Extreme risk trees may need re-inspection in 30–60 days; High risk in 90 days; Moderate risk annually; Low risk on a 3–5 year cycle. Property managers and developers should understand that a report is a snapshot, not a permanent license — conditions change, and a fresh inspection is required after major weather events, construction activity, or changes to target occupancy.

Tree #9 (Monterey pine, 34" DBH): root zone partially obscured by decomposed granite landscape. Extent of root plate heave or soil saturation unknown. Internal wood condition not assessed (resistograph not included in scope). Re-inspection recommended in 6 months or following major storm event. If re-inspection reveals progression, full resistograph analysis and/or removal recommendation will follow.

Appendices

The appendices are the supporting evidence that make the report stand up to scrutiny. They typically include: a photo log with each image cross-referenced to a specific tree number and finding in the body; a site sketch or aerial image with tree tags and target zones marked; references to the standards governing the inspection (ISA TRAQ Best Management Practices, ANSI A300 Part 1: Pruning, ANSI Z133.1 safety standards); and the arborist's CV and credential copies, including the ISA certification number. For litigation support matters, the appendix also includes a statement of qualifications and any prior testimony history. An attorney reviewing a declaration will go straight to the appendices to verify the inspector's credentials and the photographic evidence — the body text is the argument, the appendices are the proof.

Photo Appendix A, Page 12: Tree #22 — trunk cavity, south face at 8' height. Scale reference (6" ruler) visible in frame. Camera: Nikon D850, 85mm lens, f/8, natural light. Cross-reference: Visual Assessment Findings, Section 3, para. 4. Photo confirms extent of cavity noted in body text.

Anatomy of a Tree Risk Assessment Report