Decision tree

Village green iStock 000009004124XSmall 146x219Andrew Plunkett reviews two important tree root subsidence cases that considered the issue of reasonable foreseeability.

The recent decision in Robbins v LB Bexley (“Robbins”) – together with the Court of Appeal ruling in Berent v (1) Family Mosaic Housing (2) Islington (“Berent”) in July this year – offer a useful analysis of the relevant authorities in relation to “reasonably foreseeable” damage.

These judgments relate to property damage to property caused by tree roots, but the notion of “reasonable foreseeability” is a concept which applies to claims in nuisance and negligence generally.

Tree root nuisance and the background to Berent and Robbins

Nuisance is not a tort of “strict liability” any more than negligence – a duty of care only arises in relation to carrying out (or failing to carry out) a particular course of action where it is reasonably foreseeable that another party will, or may be, adversely affected by any such actions or omissions. 

Tree root subsidence claims are generally brought in both nuisance and negligence, and in practice there is little or no distinction between the two. 

A party responsible for maintaining the relevant tree(s) will only owe a duty to a property owner if it is reasonably foreseeable that the tree will, or may, cause damage to the property in question.

Assuming that the risk of damage is reasonably foreseeable, and that the tree owner owes a duty to the property owner, the scope of the tree owner’s duty to act to prevent that damage arising, or minimise the risk of such damage, is also limited to take any actions as are reasonable in the circumstances. If there is a very small risk, and the cost or trouble involved in eliminating that risk would be out of all proportion to the risk to be averted, then it does not fall within the scope of the tree owner’s duty to take such actions.

Thus, for example, in the case of Solloway v Hampshire CA 1981 the claimant’s property was situated in an area where the sub-soil consisted largely of gravel interspersed with the occasional patch or pocket of clay. Clay soil is generally known to be susceptible to subsidence due to the action of tree roots in removing moisture from the ground, causing the clay to shrink and any property on that ground to subside, but there is no such effect (or significant effect) in the case of gravel soil.

The court emphasised that the extent of any risk, and its foreseeable consequences, have to be balanced against the practical measures that can be taken to eliminate or minimise that risk. The Court of Appeal found that the likelihood of the claimant’s house standing on a pocket of clay was only a “…vague possibility, not a real risk…but assuming that there was a real risk or chance, I would say that it is an outside chance and that outside chance has to be balanced against the practical steps which could reasonably have been taken by the defendants to minimise the damage”.

In order to eliminate the risk of damage to properties which happened to be standing on clay pockets, the council would have had to carry out a survey of the land within its area in order to determine which houses were standing on areas of clay and then take appropriate steps with regard to any nearby vegetation. The court considered that this would have been entirely out of proportion to the risk – “…the cost and inconvenience of taking any effective steps to remove or reduce [the risk] would be quite out of proportion to that risk” - and the council were held not to be in breach of duty.

The issue of the steps which ought to be taken in relation to any given risk and the issue of reasonable foreseeability of damage, were stated by the court to be interlinked. Damage to the property in question, due to the relatively rare incidence of patches of clay ground, was held not to be reasonably foreseeable.

Reasonable foreseeability pre-Berent

Solloway represents a relatively rare case where the property in question happened to be situated on a patch of clay.

In cases where the sub-soil in the area is known to be clay-based, with the consequent risk of tree root subsidence, the courts have tended to take the view that those with the relevant expertise, such as local authorities, are (or ought to be) familiar with the risks of tree root subsidence and therefore that there is a risk of damage to properties in the area.

This has, in practice, been found to be sufficient to pass the “reasonable foreseeability” element of nuisance (or negligence). All other things being equal, where a property is situated on clay soil the courts have found the risk of subsidence damage by street trees to be “reasonably foreseeable” by a local authority, with the consequence that a local authority would be held to be under a duty to the property owner in question.

The emphasis in such cases would then shift to whether the local authority (or other tree owner) was in breach of duty in failing to manage the relevant trees appropriately.

Berent v (1) Family Mosaic Housing (2) Islington LBC – first instance

The first-instance decision in Berent was handed down on 25 May 2011. The facts of the case were relatively complex, but the judge was satisfied that trees owned and maintained by the defendants had caused subsidence damage to the claimant’s property due to the action of the tree roots.

However, despite the fact that the property was located in an area where the sub-soil is generally known to be clay-based (within the area of “London clay”), and the trees in question were relatively close to the claimant’s property, Judge Wilcox held that these circumstances were not sufficient to satisfy the test of “reasonable foreseeability” .

The expert evidence on both sides was to the effect that, whilst it was possible to know that there was a risk to one or more properties in the area by reason of the presence of the street trees (and the trees for which the first defendant, a housing authority, was responsible) it was not possible to know which property(ies), if any, might be damaged by tree root subsidence.

Again relying on expert evidence the judge found that there was no way to eliminate the risk of damage to properties in the area entirely except by removing all the street trees. This was an unacceptable response to the level of risk of damage: “…a responsible local authority mindful of its obligations under the Town and Country Planning Acts and the preservation of such amenities as an established treed environment could not reasonably contemplate the desertification of such a neighbourhood by wholesale tree felling”.

Whilst clearly mindful of the issue of whether the defendants had breached their duty, and that the scope of the defendants duty extended only to do what was “reasonable” to avert or minimise any risk of damage in all the circumstances, Judge Wilcox’s chief finding in relation to liability was that, in the particular circumstances of this case, the defendants were not in a position to know that there was a real risk that the trees could cause damage to the claimant’s property until after they had been notified of the damage by the claimants and provided with supporting evidence that the trees were the cause of damage.

Until they were made aware of the “real risk” posed by the trees, damage was not reasonably foreseeable; in the absence of reasonable foreseeability, no duty of care was owed by the defendants to the claimant in nuisance or in negligence; in the absence of a duty of care, there could be no liability.

As the defendants had not been notified of the damage allegedly being caused by the trees until relatively late in the day, after all (or nearly all) the relevant damage to the property had occurred, they were not liable for by far the greater part of that damage.

In legal terms, the significance of this decision lay in the recognition that in order to satisfy the test for reasonable foreseeability it was necessary to show not simply that damage to properties in the area due to tree root subsidence was foreseeable in general terms but that it was necessary that damage to the particular property in question should be foreseeable. In the circumstances of this case, no such damage was foreseeable unless and until the defendants had been notified of the damage and provided with supporting evidence.

Berent – Court of Appeal decision, July 2012

The Court of Appeal upheld the first instance decision. The issue of reasonable foreseeability of damage could not be separated from the related issue as to what it was reasonable to do in the light of the relevant risk. It may be reasonable to take no steps to eliminate a risk which is unlikely to materialise, and which will have relatively small consequences if it does. 

The thinking of the court appears to be that a risk is not a “real” risk, as opposed to a theoretical one, unless and until it is of sufficient magnitude that one ought to take account of by considering whether there are steps that ought reasonably to be taken to eliminate or minimise that risk.

The court noted that there was no assertion in this case that the relevant trees should have been identified as posing a greater risk than others. Nothing was said to the effect that the trees in that area should have been identified as a “hotspot” or problem area. In those circumstances, there was nothing that the defendants ought to have done in terms of tree management over and above the steps that they took with street trees generally.

Damage to the subject property was not “reasonable foreseeable” because there was nothing which ought to have caused the defendants to consider whether further steps should have been taken with regard to managing the relevant trees (prior to notification by the claimants), and therefore there was no duty, let alone any breach of duty, and no liability for damage which occurred before that date.

Lord Justice Tomlinson in his leading judgment also noted that “The social utility of the activity which gives rise to the risk falls to be considered”. The “social utility” of tree lined streets (as was more specifically emphasised in the first instance judgment) was no doubt a factor which the court bore in mind.

Mrs Josephine Robbins v London Borough of Bexley August 2012

Robbins is (so far as I am aware) the first reported decision on tree root nuisance since the Court of Appeal decision in Berent. Although the case was heard prior to Berent, and judgment was prepared in draft by the end of April Mr Justice Edwards-Stuart reserved judgment pending Berent to allow him the opportunity to consider the views of the Court of Appeal. He addressed their findings specifically toward the end of his judgment (from paragraph 168 onward).

The particular interest of Robbins, from the point of view of tree root claims (and, indeed, issues relevant to nuisance and negligence claims in general) is the treatment of “reasonable foreseeability”.

The judge stated that whilst Berent contained a “helpful and illuminating analysis of the relevant authorities”, that judgment makes it clear that “…there are no special principles of law that relate to tree root cases: they are subject to the general law of negligence and nuisance”.

In Robbins the date on which Mrs Robbins’ representatives notified Bexley Council (“Bexley”) that the trees were apparently causing damage to her property is not entirely clear from the recorded judgment but appears to have been in or about March 2004, following the claimant’s discovery of crack damage to her property in September 2003.

However, the judge found that damage to the claimant’s property by the relevant trees was reasonably foreseeable by Bexley long before then, from early 1998 (at the latest). The chief reason for this was that, unlike any other trees in the vicinity, the poplars maintained by the council which the judge identified as the cause of damage in this case had given rise to a number of other claims in the vicinity in the past. In the course of those claims the council had become well aware of the distance that the roots of the poplars extended, and it was reasonably foreseeable that any house in the relevant street with an extension that was within 35m of one of the poplars was at “real risk” from subsidence caused by the poplar roots.

In the light of that knowledge Bexley ought to have taken steps to reduce that risk by carrying out works to the relevant trees (specifically crown reduction on a cyclical basis) from 1998, which the judge found would have prevented the damage. Having failed to take those reasonable steps, Bexley were in breach of duty and were liable to the claimant for the cost of repairs.

Implication of Berent and Robbins

The finding of the court in Robbins is not at odds with that in Berent. Indeed, there are statements in Berent, such as the fact that the absence of any evidence that the relevant trees should have been regarded as a “hotspot” or problem area, which illustrate the differences between the underlying facts in both cases and from which one might reasonably suppose that, on the facts in Robbins, the Court of Appeal are likely to have made the same findings.

The fact that there had been a number of claims in the past in the vicinity of the subject property and in relation to the relevant trees indicates that Mrs Robbins property was located in just the sort of “hotspot” that might have caused a duty of care to arise.

Robbins does emphasise however that the issue of whether or not damage by tree roots is “reasonably foreseeable” depends upon the facts in any particular case. There is no absolute requirement that damage will only be “reasonably foreseeable” once the defendant has been notified of the damage (and provided with supporting evidence) by the claimant. One can envisage various circumstances in which the “real risk” of damage to a particular property may come to the attention of a local authority or other tree owner.

This does not alter the fact however that in many cases of tree root damage there may be no particular distinguishing features which mark out one particular property as being more at risk than other properties in the wider area, and where the local authority (or other tree owner) will not be deemed to have a duty, or a liability, until after notification by the claimant or their representatives.

Whether it is to be regarded as a clarification of the law relating to tree root nuisance or a refinement, the fact that in order to satisfy the test of “reasonable foreseeability” one must establish that damage to the property in question, rather than to the any one/some unspecified properties in the general area, was reasonably foreseeable to the relevant party, represents a shift in tree root law.

The facts of Berent were unusual in that there was a long delay by the claimant’s representatives in notifying the defendants of the damage and the alleged cause of that damage, so the finding that no duty arose until after notification was of particular importance.

Nevertheless, in (almost) every tree root claim there is, of necessity, some delay between identification of the damage and its likely cause, and notification of the defendant(s). Whilst that early, initial damage may in many cases be relatively small, these are losses which occur in almost every claim of tree root nuisance, for which local authority and other insurers may no longer be held responsible post-Berent.

The issue of reasonable foreseeability is of course not restricted to claims for tree root damage, but is of general relevance to claims in nuisance and negligence, as was emphasised in the Court of Appeal decision, which drew its conclusions based on a consideration of “reasonable foreseeability” in nuisance and negligence claims generally.

On a theoretical level one might question the closeness of the link drawn by the Court of Appeal between the issue of whether damage is reasonably foreseeable (and therefore the existence of a duty of care), and the issue of scope of duty and whether the defendant has breached that duty, notwithstanding that there is precedent for this link in case law.

There is clearly some risk of damage to any property within influencing distance of a street (or other) tree, it might be sufficient in considering liability to consider the scope of duty that the perceived risk gives rise to, and to assess whether the tree owner has taken the appropriate steps and has complied with its duties given the level of risk.

On a more general, policy level, the decision in Berent is an indication that the courts are increasingly willing to recognise the value of trees as a social amenity, and to take that into account in assessing how they should be treated.

Finally, it must be noted that the claimant in Berent has appealed to the Supreme Court – the issues it has raised are by no means closed.

Andrew Plunkett is a lawyer at Berrymans Lace Mawer. He can be contacted by This email address is being protected from spambots. You need JavaScript enabled to view it.