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.
What an arborist looks at
A risk assessment considers the likelihood of failure (defects such as decay, cracks, weak unions, root damage or lean), the likelihood of hitting a target (house, driveway, play area), and the consequences. The ISA Tree Risk Assessment Qualification (TRAQ) is a credential specific to this work; ask whether the assessor holds it.
Common Roanoke Valley findings
- Ash decline from emerald ash borer. The Virginia Department of Forestry runs a cost-share program for treating qualifying ash trees (at least 12 inches in diameter with no more than 30% crown loss).
- Oak decline and oak wilt concerns, where pruning timing matters.
- Construction damage to roots from new driveways, additions or utility trenches.
- Codominant stems with included bark that can split in storms.
Is an arborist worth the cost?
An assessment can save money when the answer is "prune, don't remove," and it gives you documentation if a neighbor's tree or a claim is involved. It is also useful before buying a wooded property.
What you receive
Depending on scope, you may get a verbal opinion during an estimate visit or a written report that identifies the tree, the defects found, the targets, the risk rating and recommended actions with timelines. A written report is worth requesting when a neighbor dispute, insurance question or HOA approval is involved.
Preserving trees during construction
An arborist can mark a tree protection zone before an addition, driveway or utility trench goes in. Fencing that zone and keeping vehicles, spoil piles and trenching out of it is the single most effective way to keep a mature tree alive through construction.
When to book an assessment
- A large tree within striking distance of your house, driveway or play area shows defects.
- After a major storm, if a tree lost large limbs or shifted.
- Before buying a wooded property, or before building near mature trees.
- When neighbors disagree about a tree on the line.
- When an ash tree may be treatable under the DOF cost-share program, which requires an assessment by a DOF forester.
Defects an arborist looks for
| Defect | Why it matters |
|---|---|
| Decay, cavities, fungal conks | Reduce the wood that holds the tree up |
| Cracks and splits | Can lead to sudden failure |
| Codominant stems with included bark | Weak unions that split in wind or ice |
| Root damage or root plate lifting | Whole-tree failure risk |
| Dead branches and hangers | Falling-limb risk over targets |
| Lean, especially new lean | Indicates root or trunk failure |
Options other than removal
Depending on findings, recommendations may include crown cleaning, reduction pruning to reduce weight on a weak limb, cabling or bracing to support a weak union, moving a target (such as a play set) out of range, soil and root-zone care, pest treatment, or monitoring with a follow-up visit. Removal is one option among several.
Credentials worth asking about
ISA Certified Arborist is the broad credential for tree care professionals; the ISA Tree Risk Assessment Qualification (TRAQ) is specific to risk evaluation. Ask which credentials the person assessing your tree holds.
Preparing for the visit
- List the trees you are concerned about and why.
- Note any history: past storm damage, construction near the roots, recent lean.
- Clear access around the base so the trunk flare can be inspected.
- Have your property survey handy if a boundary tree is involved.
After the assessment
Act first on high-risk findings near frequently used areas. Lower-risk items can be scheduled for the dormant season. Keep the written report; it is useful for insurance conversations, HOA approvals and future reassessments.
Ash trees: treat, remove or wait?
Emerald ash borer kills most untreated ash. Healthy, valuable ash can often be protected with treatment, and the Virginia DOF cost-share may pay up to 70% for qualifying trees during the application window. Ash already in heavy decline becomes brittle and is safer to remove sooner rather than later. See our ash and oak disease guide.
Levels of tree risk assessment
| Level | What it involves | Typical use |
|---|---|---|
| Limited visual | A quick look from the ground for obvious defects | Screening many trees, such as along a long driveway |
| Basic | A detailed ground-level inspection of one tree, with simple tools such as a mallet and binoculars | Most residential assessments |
| Advanced | Specialized methods such as aerial inspection, resistance drilling or root excavation | High-value trees or unclear findings |
Levels as described in ISA's tree risk assessment framework (general description).
Trees and real estate
Buyers of wooded lots around Roanoke can ask for an assessment of large trees near the house before closing. Defects found then can be negotiated like any other inspection item, and the report gives you a baseline for later.
Neighbor trees
If a neighbor's tree worries you, an independent assessment gives both parties a neutral starting point. Share the report and discuss options; for trees on public land, contact the locality.
Cabling and bracing
Steel cables high in the crown or rods through weak unions can reduce the chance that a split develops into failure. They need periodic inspection and are not a fix for trees with serious decay. An arborist can tell you whether a tree is a good candidate.
Assessment vs. free estimate
Many tree companies give free removal estimates, and an experienced estimator can often spot obvious problems. A formal risk assessment goes further: it documents defects, targets and risk ratings, and recommends actions with timelines. If the decision is close or the tree is valuable, the formal route is worth it.
Oaks and oak wilt
Oak wilt is a fungal disease spread by sap beetles to fresh wounds and through root grafts between nearby oaks. The VCE guidance we cite advises pruning oaks in November and December where possible, avoiding March through August, and sealing wounds if pruning must happen then. An arborist can help tell oak wilt from other causes of oak decline.
Trees on or near public land and lines
Trees in a VDOT-maintained right-of-way cannot be trimmed or cut without a VDOT land use permit (24VAC30-151), even when the tree seems to belong to your yard. Apply through the local VDOT residency office.
For trees near lines running pole to pole, Appalachian Power customers can request a forestry inspection at 800-956-4237.
Common questions
How much does it cost to have an arborist look at a tree?
Fees vary by company and scope; some include a basic look with an estimate, while formal written risk assessments are billed separately. Ask up front.
Can an arborist save a tree?
Often. Pruning, cabling, treating pests such as emerald ash borer, or correcting soil problems can extend a tree's life.
Do I need an arborist for tree removal?
Not always, but an arborist opinion is valuable for large trees near structures or when you are unsure whether removal is necessary.