Hazard tree assessment

A hazard assessment is worth scheduling when the answer to "does this tree need to come down" is not obvious, when there is liability or insurance context, or when the tree is large enough that removal would be a significant expense.

The situations where assessment beats jumping straight to removal: after a major storm where the tree may have shifted but is not visibly failing; after a neighbor's tree failed and you want to know about your own; when you notice a change in a tree (lean that was not there before, cracks at the base, fungal conks, soil heaving on one side); when you are buying or selling a property and a large tree is part of the inspection conversation; when a contractor has quoted removal but you want a second opinion; and when liability is real (the tree is positioned to hit a neighbor's structure, vehicle, or a public sidewalk).

The situations where assessment is overkill: trees clearly past the point of preservation (advanced visible decay, severe structural failure, dead crown), trees with a clearly mitigable issue (single dead limb that needs removal), and small enough trees that the assessment cost is disproportionate to the work cost.

A good arborist will tell you on the phone whether your tree needs an assessment or can be quoted directly for the appropriate work.

The legal standard for tree liability in most US jurisdictions hinges on whether the owner "knew or should have known" the tree was a hazard. A written assessment from an ISA-certified arborist establishes the knowledge baseline either way:

If the assessment recommends removal and you do nothing, and the tree fails: you knew, and you have liability exposure for the failure.

If the assessment recommends preservation with a re-assessment interval, you follow the recommendation, and the tree fails between intervals: you took reasonable action, and your liability exposure is meaningfully lower.

If the assessment recommends mitigation (cabling, target reduction) and you complete it, and the tree fails despite the work: you took reasonable action, and you have documentation supporting that.

Without a written assessment, the liability question becomes a fact dispute about what you "should have known" — which is usually decided against the property owner when visible warning signs (conks, lean, recent change) were present and unaddressed.

This is why assessments are particularly worth commissioning when a tree is positioned to hit a neighbor's property, a public sidewalk, or a structure not your own. The assessment fee is small relative to the liability exposure if a tree fails on someone else's structure or vehicle.

A standalone hazard assessment typically takes 30-60 minutes on-site plus 1-3 business days for the written report. The cost is modest relative to a removal and is sometimes credited back toward the work if you proceed with the recommended action through the same arborist.

The credit-back arrangement varies. Some arborists credit the full assessment fee against subsequent work. Some credit a portion. Some treat the assessment as a separate professional service not eligible for credit. Ask up front so the financial picture is clear.

Multi-tree assessments (whole-property surveys for larger lots) usually price more efficiently per tree than single-tree assessments. If you have several trees of concern, ask for a property walkthrough rather than individual assessments.

For real-estate transaction context (buyer or seller commissioning the assessment as part of a sale), the assessment is paid up front by whichever party requested it, and the report is shared between the parties as part of the transaction documentation.