Most businesses can tell you when the boiler was last serviced, when the fire alarm was last tested, and when the lift was last certified. Ask when the mature beech at the edge of the car park was last inspected by someone qualified to assess it, and the answer is usually a pause.

Trees occupy an odd position in commercial risk management. They are conspicuous, they are often the most valuable landscape feature on a site, and they are almost never on the maintenance schedule. Then a limb comes down on a parked car, or a whole tree fails across a footpath, and the question of who was responsible for knowing it was going to happen becomes a very expensive one.

The duty is not optional and it is not passive

If your business occupies land with trees on it, you owe a duty of care under the Occupiers’ Liability Act 1957 to anyone lawfully on that land, and a lesser but real duty under the 1984 Act even to trespassers. Where a tree overhangs a road or footpath, the Highways Act 1980 gives the highway authority powers to compel action and to recover costs.

The important word in all of this is reasonable. The law does not require that trees never fail. Trees are living structures and some proportion of them will shed limbs regardless of what anyone does. What the law asks is whether the occupier had a reasonable system in place for identifying foreseeable risk, and whether that system was actually followed.

Courts have consistently framed the test around inspection. Not around outcome, and not around whether the defect was obvious in hindsight, but around whether a landowner had arranged for someone competent to look at the trees at sensible intervals, and whether that person would have spotted the problem. Where a business can produce records showing a periodic inspection regime by a suitably qualified person, the defence is strong even when a tree has failed. Where there are no records at all, the position is weak even when the failure was genuinely unforeseeable.

The absence of a paper trail is, in practice, the liability. This is why arboricultural contractors such as Red Oak Tree Care are increasingly asked for written condition surveys rather than a verbal quote to take a tree down. A quote is a commercial document. A survey is evidence.

What a defensible regime actually looks like

The National Tree Safety Group, whose guidance is widely treated as the reference point in this area, sets out an approach based on proportionality rather than blanket inspection. The core idea is straightforward. Assess trees according to the likelihood that a failure would hit somebody.

A tree in the middle of a fenced field poses a negligible risk to people regardless of its condition. The same tree, in the same condition, standing beside a school gate or a busy loading bay, requires a different level of attention. Zoning a site by target occupancy is the first step, and it is the step that keeps the cost of the whole exercise proportionate.

For most commercial sites, a workable regime looks like this. An informal walkover by a member of staff who has been briefed on the obvious warning signs, carried out a few times a year and particularly after severe weather. A formal inspection by a qualified arboriculturalist at intervals determined by the risk zoning, typically somewhere between one and five years. A written record of both, retained.

The warning signs a non specialist can be trained to spot are not subtle. Fungal fruiting bodies at the base or on the stem. Cracks or splits in major limbs. Cavities and decay pockets. Soil heaving or lifting on one side of the root plate. Sudden leaf loss out of season. A distinct lean that was not there last year. None of these confirms a tree is dangerous. All of them justify a call to someone who can tell you.

The insurance dimension people forget

There is a second financial exposure that has nothing to do with falling branches.

Across much of southern England, and particularly on the shrinkable clay soils that run through Surrey and the surrounding counties, tree roots are implicated in a significant share of subsidence claims. Clay expands when wet and contracts when dry. A large tree drawing moisture from beneath a shallow foundation during a dry summer can cause differential movement in a building, and the resulting cracking is expensive to remediate.

Where a claim is made against a neighbouring landowner whose tree is alleged to be the cause, the question of whether that landowner knew, or ought to have known, about the risk becomes central. Insurers examine tree management records. A business that has been actively managing its trees, with crown reductions carried out at appropriate intervals and documented, is in a materially better position than one that has left everything to grow unchecked for twenty years.

The inverse problem also exists. Remove a mature tree that has been drying out clay soil for decades, and the ground can rehydrate and heave, lifting foundations upward. This is why the reflexive answer to a tree near a building is not always to fell it, and why the decision should not be made by whoever happens to be holding the chainsaw.

Development sites and the cost of finding out late

For anyone acquiring or developing commercial property, trees carry a distinct category of risk that surfaces at exactly the wrong point in the transaction.

Tree Preservation Orders and conservation area designations restrict what can be done to trees regardless of who owns the land. A protected tree standing where the access road needs to go is a planning problem, a programme problem, and occasionally a deal breaker. Breaching a preservation order is a criminal offence, and sentencing takes account of any financial benefit the offender obtained, which means the calculation that it might be cheaper to fell the tree and pay the fine has been closed off deliberately.

BS 5837, the British Standard covering trees in relation to design, demolition and construction, sets out how an arboricultural impact assessment should be produced and how root protection areas should be calculated. Planning authorities expect to see it. Commissioning that work at the feasibility stage, before the design is fixed, costs a fraction of redesigning around a constraint discovered at planning committee.

Where businesses go wrong

Three failures account for most of the exposure.

The first is treating tree work as a grounds maintenance line item to be awarded on price. The gap in competence between a certificated arboriculturalist and a two person outfit with a chainsaw and a van is enormous, and it is invisible until something goes wrong. Ask for NPTC or equivalent certification covering the specific operations involved, and ask for the public liability certificate rather than accepting an assurance.

The second is failing to keep records. An inspection that happened but was not written down provides no protection whatsoever in a claim.

The third is reacting rather than planning. Emergency tree work carried out after a storm, at short notice, in poor conditions, costs several times what the same work would have cost as a scheduled operation, and it happens at the moment when every contractor in the region is fully booked.

A modest suggestion

Trees are assets. They raise property values, they contribute to biodiversity commitments that increasingly appear in reporting frameworks, and they do things for the experience of a workplace that no amount of interior design achieves. They are also structures that can kill people, and the law treats them accordingly.

Put them on the risk register. Establish who is responsible for them. Get a qualified survey of anything large enough to hurt someone. Keep the paperwork. The cost of doing all of that, for a typical commercial site, is smaller than most organisations spend annually on the coffee machine.