If you own property in British Columbia, there is a good chance you will need an arborist report at some point. Whether you are applying for a tree removal permit, planning a renovation, dealing with a neighbour dispute, or responding to storm damage, arborist reports are the professional documents that municipalities, insurers, and courts rely on to make decisions about trees.
Understanding what goes into these reports, how to read the key sections, and what the recommendations actually mean will help you make informed decisions and avoid costly mistakes.
What an Arborist Report Contains
A professional arborist report is a structured document that records the findings of a qualified arborist's assessment. While formats vary between practitioners, most reports include the following core components.
- Tree inventory. Species identification, measurements (DBH, height, crown spread), location mapping, and age estimates for each tree assessed
- Health assessment. Observations on crown density, foliage colour, evidence of disease or pest damage, structural defects, and overall vigour
- Risk rating. A structured evaluation of the likelihood of failure and the potential consequences, using standardized methodology
- Recommendations. Specific actions such as retain, remove, monitor, prune, or further investigate
- Photographs and site plan. Visual documentation of the trees and their relationship to structures, utilities, and property boundaries
- Arborist credentials. The assessor's ISA number, TRAQ qualification, and professional liability information
Types of Arborist Reports
Not all arborist reports serve the same purpose. The type of report you need depends on your situation.
Tree Risk Assessment
A risk assessment evaluates the probability of a tree or tree part failing and the potential consequences if it does. These reports use the ISA's Tree Risk Assessment methodology (TRAQ) to assign a risk rating of Low, Moderate, High, or Extreme. Risk assessments are commonly requested after storm events, when a tree appears to be declining, or when a property owner has concerns about safety.
Tree Inventory and Management Plan
An inventory catalogs all significant trees on a property, documenting species, size, health, and condition. Management plans build on inventories by providing a multi-year schedule of recommended maintenance. These are common for strata properties, parks, commercial developments, and institutional campuses.
Pre-Construction Assessment
Required for most development permits in BC, pre-construction reports assess the impact of proposed construction on existing trees. They identify which trees can be retained, which will need to be removed, and what protection measures (TPZs, root pruning, monitoring) are required during construction.
Tree Preservation Plan
Often part of a development permit application, preservation plans detail exactly how retained trees will be protected during construction. They specify TPZ fencing locations, excavation restrictions, monitoring schedules, and remediation measures if damage occurs.
How to Read Risk Ratings
The risk rating is often the most important part of a report for property owners. Understanding what the ratings mean helps you prioritize actions and make sound decisions.
- Low risk. No significant defects or hazards. Normal maintenance only. Most healthy urban trees fall into this category
- Moderate risk. Some defects or conditions that could lead to failure under certain circumstances. Monitoring or mitigation recommended
- High risk. Significant probability of failure with potential for serious consequences. Action is recommended within a defined timeframe
- Extreme risk. Failure is imminent or has already begun. Immediate action required, which may include restricting access to the area
Important context. Risk is always relative to the target. A tree with significant decay overhanging an empty field has different risk implications than the same tree over a busy playground. Risk ratings consider both the likelihood of failure and the consequences if it occurs.
Understanding Report Recommendations
Arborist reports typically conclude with specific recommendations for each tree. Understanding what these terms mean in practice will help you plan and budget accordingly.
Retain
"Retain" means the tree is in acceptable condition and should be preserved. This does not mean the tree requires no maintenance. Retained trees should still be monitored periodically, and routine pruning may be recommended to maintain structural integrity and clearances.
Remove
"Remove" is recommended when a tree poses an unacceptable risk, is in irreversible decline, is dead, or conflicts with approved development plans. Removal recommendations typically include a timeframe (immediate, within 6 months, within 1 year) that reflects the urgency of the situation.
Monitor
"Monitor" indicates that the arborist has identified a condition that warrants ongoing observation but does not currently require intervention. Monitoring recommendations typically specify the frequency (annually, semi-annually) and what the arborist is watching for. This is common for trees with early-stage decay, minor structural defects, or conditions that may improve or worsen over time.
How Reports Are Used
Municipal Permits
Most BC municipalities require arborist reports for tree removal permits and development applications. The report provides the professional justification that the municipality needs to approve or deny the request. Reports that follow recognized standards (ISA BMP) and are prepared by qualified arborists (ISA Certified, TRAQ Qualified) carry the most weight.
Insurance Claims
After storm damage or tree failure, insurance companies rely on arborist reports to assess causation, evaluate property damage, and determine coverage. A well-documented report with photographs, risk analysis, and professional opinion can significantly strengthen your claim.
Legal Disputes
Arborist reports serve as expert evidence in legal disputes involving trees, including neighbour disputes, liability claims, and property damage cases. Courts give significant weight to reports prepared using standardized methodology by credentialed professionals. A defensible report follows a consistent, documented methodology and avoids subjective language.
What Makes a Report Defensible
Not all arborist reports are created equal. A defensible report is one that would hold up to scrutiny by other professionals, municipal reviewers, or courts.
- Prepared by an ISA Certified Arborist, ideally with TRAQ qualification for risk assessments
- Uses standardized methodology (ISA BMP for Tree Risk Assessment, ANSI A300 standards)
- Includes detailed observations, not just conclusions. The data should support the recommendations
- Contains clear photographs, accurate measurements, and a site plan
- Acknowledges limitations (e.g., "assessment limited to visual inspection; internal decay cannot be ruled out without advanced testing")
How to Choose a Qualified Arborist for Your Report
The quality of your arborist report depends directly on the qualifications and experience of the arborist who prepares it. Look for current ISA Certified Arborist credentials, TRAQ qualification (especially for risk assessments), familiarity with your local municipality's requirements, professional liability insurance, and a track record of preparing reports that are accepted by municipalities and hold up in legal settings.
Ask for a sample report before engaging an arborist for the first time. This gives you insight into their level of detail, communication clarity, and professional standards. A good arborist report should be understandable to a layperson while meeting the technical standards expected by professionals and regulators.
Need a Professional Arborist Report?
Our TRAQ-qualified arborists prepare defensible reports accepted by municipalities and insurers across BC.
Call (778) 583-8986