bmtreeconsultancy

Decay Investigations

Identify Hidden Tree Defects Before They Become Hazards

At Black Mountains Tree Consultancy, our decay inspection services are designed to assess the internal structural condition of trees that may appear outwardly healthy but could be hiding serious weaknesses. Internal decay, cavities, or structural defects can pose a significant hazard, especially in highly populated locations such as schools, roadsides, or public parks.

All inspections are carried out by a highly qualified tree inspector with many years of experience in decay analysis, using recognised strength/loss calculation techniques and Visual Tree Assessment (VTA) methodology. Where required, we recommend or oversee additional investigation methods such as climbing inspections or specialist decay detection equipment.

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Hollow tree stump with a measuring tool

Why Decay Investigations Are Important

Internal decay can develop over years without obvious external signs. A tree with advanced internal rot may remain upright until a storm or wind event causes it to fail, sometimes with catastrophic consequences.

Our inspections help to:

  • Detect hidden decay before it leads to failure
  • Support decisions on pruning, bracing or removal
  • Monitor trees of concern over time
  • Provide legal protection through documented due diligence
  • Preserve veteran or significant trees wherever possible
This service is often used to complement routine tree safety surveys or to provide further investigation where concerns are raised about individual trees.
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Close-up of a tree trunk showing internal decay and wood defects being inspected for safety.

What the Investigation Involves

We begin with a thorough visual assessment of the tree, its base, trunk, root flare, crown and canopy, noting signs such as:
  • Fungal fruiting bodies
  • Cavities or hollows
  • Cracks, bulges or sunken areas
  • Unusual crown dieback
Where concerns exist, we may recommend:
  • Mallet sounding (to detect hollow or weak areas)
  • Climbing inspection for closer assessment
  • Decay detection tools such as resistographs or tomographs (via partner labs or contractors)
All findings are summarised in a clear, prioritised report with risk ratings and management recommendations.
Arborist inspecting a tree trunk and branches, checking for health and structural issues.

Who Should Consider a Decay investigation?

This service is particularly valuable for:
  • Landowners with mature or veteran trees
  • Managers of public spaces, schools, or care homes
  • Trees with visible fungi, wounds or cavities
  • Sites with legal duties of care under Occupiers’ Liability Acts
  • Trees with historic value or planning constraints

If you suspect internal decay, early detection could preserve the tree or prevent an incident.

Why Choose Black Mountains?

  • Lantra-accredited inspection by a qualified consultant
  • Thorough, impartial and independent advice
  • Experience with high-risk, protected and veteran trees
  • Practical, clear reporting to support informed action
  • Optional follow-up support and bracing recommendations
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Book Your Decay Investigation Today

We work across all of Wales, the West Midlands, South West England and beyond and can travel nationally for larger or complex cases.

Concerned about a tree’s internal condition?

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FAQ: Decay Investigation

What is a tree decay investigation?
A detailed assessment to identify internal weaknesses such as rot, cavities or fungal decay that could compromise tree safety or stability.
Fungal brackets, reactive growth, cracks, sunken areas, dead bark, or hollow soundings areas are all common indicators – but sometimes there are no outward signs.
We start with a visual inspection, then may use sounding tools, climbing access, or refer for resistograph or tomograph testing.
Yes – while we don’t carry out tomography in-house, we refer to trusted labs and can supervise the process and interpret results.
Not always. It’s only used when decay is suspected higher up in the canopy or above the height at which a visual inspection can be safely carried out.
We’ll provide a written report detailing the findings, risk level, and suggested actions — such as monitoring, bracing, or tree work.
No — but it can often be managed through pruning, bracing, or changes in site use to reduce risk while preserving the tree.
Decay inspections can be a follow-up to a general survey or requested as a standalone service for specific trees of concern.
Yes – and if work is needed, we can support your TPO application with an evidence-based report.
Costs depend on tree size, location, and the level of investigation needed. Contact us for a tailored quote.