Big trees near homes make people nervous, especially after a storm brings down a neighbor's oak. But many large trees are perfectly sound, and removing a healthy shade tree costs money and takes decades to replace. A risk assessment replaces guesswork with a structured evaluation.
What an assessor looks at
- Targets: what the tree or a part of it would hit if it failed, such as the house, driveway, play area or power line, and how often people are there.
- Site: soil, slope, drainage, recent construction or grading, and exposure to wind.
- Roots and root flare: decay, fungal fruiting bodies, girdling roots, severed roots, soil heaving.
- Trunk: cavities, cracks, seams, cankers, lean.
- Branch structure: co-dominant stems with included bark, overextended limbs, deadwood, hangers.
- Crown: dieback, density and signs of pests or disease.
Levels of assessment
A basic assessment is a detailed visual inspection from the ground. If it finds something that needs more information, such as possible internal decay, an advanced assessment may use tools such as a mallet, probe, resistance drill, or aerial inspection by a climber.
Options other than removal
- Removing deadwood or a single defective limb.
- Reducing the length or weight of overextended limbs.
- Installing cabling or bracing to support weak unions.
- Moving the target (relocating a play set or parking spot).
- Monitoring the tree with periodic re-inspection.
Who should do it
Ask for an ISA Certified Arborist, and if you want a formal risk assessment, ask whether the arborist holds the ISA Tree Risk Assessment Qualification (TRAQ). Expect a written summary of findings and recommendations.
When to get one
- Before buying a property with large trees close to the house.
- After a storm, if a tree has a new lean, cracks or exposed roots.
- Before construction near trees you want to keep.
- When a neighbor has raised concerns about your tree.
- If you see mushrooms or conks at the base of a large tree.
Neighbor trees
If a neighbor's tree worries you, a written assessment can be a calmer starting point for a conversation than a demand. Rules on overhanging branches and liability vary; for disputes, consult an attorney.
What you get
A useful assessment identifies each tree assessed, describes defects and their location, names the targets that could be affected, rates the likelihood of failure and the consequences, and recommends options: no action, monitoring, pruning, cabling or removal, with a suggested timeframe. Ask for the findings in writing with photos. For trees near Smith Mountain Lake, a written assessment can support an application to remove dead, dying or diseased vegetation under Appalachian Power's shoreline rules; see our Smith Mountain Lake page.
After the assessment
Use the report to prioritize. Address high-risk trees over occupied areas first, schedule pruning in the right season, and recheck trees you are monitoring after major storms. Our remove or trim guide and storm prep checklist complement an assessment.
Questions to ask the assessor
- Are you an ISA Certified Arborist, and do you hold the Tree Risk Assessment Qualification?
- Which trees will you assess, and at what level of detail?
- Will the report include photos and recommended timeframes?
- Do you also sell the work you recommend, and will you price alternatives?
Use our free quote form to request an assessment.