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Tree risk: likelihood × consequence

Risk is not danger. A dead tree in a field is not risky; the same tree over a bedroom is. The whole method is two questions — how likely is failure, and what is underneath — and the answer is a tier, not a number.

Pre-filled with a realistic job. Change any input and the figure updates as you type — nothing is sent anywhere, and Print gives you a clean sheet without the buttons.

Monitorlikelihood 2 × consequence 3 = 6

Mitigate the target or the defect; re-inspect within a year.

  • LikelihoodPossible
  • ConsequenceSignificant
  • Matrix score6
  • Assessed2026-09-04

Observed defects

Pre-filled with the defects a walk-around should check. Edit them to match this tree, then print.

The matrix

Likelihood ↓ / Consequence →NegligibleMinorSignificantSevere
ImprobableSoundSoundSoundMonitor
PossibleSoundSoundMonitorMonitor
ProbableSoundMonitorRemoveRemove
ImminentMonitorRemoveRemoveRemove

Note what the table does: a severe target on its own does not produce a removal, and a probable failure over nothing does not either. Both sides have to be loaded. That is the discipline the matrix enforces on an anxious walk-around.

Mitigation works on either axis

Because risk is a product, you can lower it from either side. Reduce the likelihood by pruning end weight, installing a support system, or correcting a structural defect. Or reduce the consequence: move the parking space, relocate the play equipment, fence off the drop zone.

Sound

Moving the target is the cheapest mitigation available and the one most often overlooked. A swing set relocated twenty feet can take a tree from Remove to Monitor for nothing.

Print it and keep it

A dated assessment is a document, and documents matter twice: insurers frequently treat a known hazardous tree as a maintenance failure, and most tree ordinances require the hazard to be evidenced before an exempt removal. The print button gives you a clean sheet with the defect list you edited and today's date on it.

Drop zone

This form is a structured way to think, not a qualified assessment. Where the tier is Remove, or where there is any doubt, the next step is a qualified arborist on site — see how to verify one.

Sources

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