From the monthly edition of Court Circular for January 2014 Zurich Municipal

We featured the High Court's judgment in this case in our November 2012 edition.

The claimant, C, owns and resides in one of several semi-detached houses backing on to a park for which the defendant, D, is responsible. Two Hybrid Black Poplar trees in the park stood approximately 30 metres from C’s property.

In 2003 C noticed cracking to parts of her property, including a single-storey extension. In 2006 the cracking worsened. C removed a nearby magnolia tree, and some of D's poplars were severely pruned, which reduced the movement to C's property. C claimed the cost of underpinning and repairing her property, alleging D's trees were responsible for the damage.

Owners of other properties in the road had submitted claims to D regarding subsidence damage allegedly caused by D’s trees from 1996/97.

The High Court held that, by 1998, the roots could have extended up to 35 metres, causing reasonably foreseeable damage to shallow foundations, as used in extensions built in the 1960s and 1970s. D should have foreseen that any extensions in the C’s road falling within approximately 35 metres of D’s trees might suffer subsidence damage from its trees.

The court held that from 1998 to 2005, D should have pruned the trees regularly, given D’s awareness of the foreseeable risk of property damage from their roots, particularly trees within 35 metres of a house. There was no documented evidence of D’s practice between 1998 and 2006 because D had then believed it was not obliged to operate a system to manage the trees in question. From 2006, D's policy was for the trees to be pruned every four years. The judge also said that, had D operated a cyclical pruning policy from 1998, which required its contractors to carry out a 25% crown reduction, the contractors would probably have carried out greater pruning than their 25% remit, and this would have averted the damage. The court therefore held D liable for the damage in 2003 and 2006.

D appealed. It contended, among other things, that even if it had operated and documented a cyclical system of pruning from 1998, damage would still have occurred. D also disputed the judge's findings as to the contractors going beyond their remit with the pruning.

The Court of Appeal held the High Court was entitled to find that, from 1998, damage from D's trees' roots was foreseeable to D. Since then, D had breached its duty to take reasonable steps to prevent its tree roots from damaging C's property. D did not have to operate a specific regime to manage the trees; the trial judge had only considered the possibilities available to D.

The Court upheld the ruling that D was responsible for the damage in 2003 and 2006, for failing to carry out cyclical pruning until 2006.

Regarding causation, the Court held D's breach of duty was in failing to act. The Court held the trial judge was entitled to find that, had a system of cyclical reduction works operated from 1998 onwards, it would have involved greater reduction than the later works orders specified.

The appeal was dismissed.

Comment: From this ruling, local authorities will wish to re-consider the notion of 'reasonable foreseeability' regarding their duty to operate a tree management policy. There should be evidence of maintaining a policy of tree management that is reasonable in the circumstances, as well as records of the history of related claims and the steps taken in response. Resources permitting, they might also consider increased consultation with arboriculturalists regarding maintenance programmes. We have also recently seen the significance of the duty on householders themselves, concerning potential property damage from trees, in Khan v Harrow LBC and Khan, featured in our November 2013 issue. Please click here for full judgment.

Date: 2013-09-03

Expertise: Property Damage

Reasonable foreseeability and private individual owners of domestic property

3 September 2013

1. This morning, Mr Justice Ramsey handed down judgment in Khan and Khan v. (1) London Borough of Harrow; and (2) Helen Sheila Kane, which considered whether tree root subsidence damage was reasonably foreseeable to a private individual owner of a domestic property whose trees caused damage to a neighbouring property.

2. The judgment is required reading for all practitioners handling tree root subsidence claims. It is particularly relevant to insurers claiming against, or defending, private individual owners of domestic properties.

The Facts

3. Mr and Mrs Khan owned a house in Stanmore, Middlesex. Mrs Kane owned the neighbouring property to the right[1] of the Khans' property.

4. There was a Lawson Cypress hedge on Mrs Kane's property about 10.0m high and 0.5m away from the Khans' house. There was also an oak tree on Mrs Kane's property.

The Issues

5. Mrs Kane admitted that her Lawson Cypress hedge and oak tree caused and/or contributed to the damage to the Khans' house.

6. However, Mrs Kane asserted that the damage was not reasonably foreseeable to her as an ordinary private individual owner of a domestic property. She also raised breach of duty, contributory negligence, failure to mitigate and points on quantum.

Reasonable Foreseeability – The Law

7. The Judge considered a number of leading authorities on reasonable foreseeability including the Wagon Mound No. 2.

8. The Judge found that the issue of reasonable foreseeability is not a subjective test depending on the peculiar characteristics of the particular defendant but is an objective test as to what ought to have been known to a reasonable person in the position of the defendant. "In this case, the relevant person is a reasonably prudent landowner."

9. A defendant's lack of subjective knowledge cannot lower the standard. However, a defendant's subjective knowledge can impose a higher standard. The Judge found:

"In my judgment, the purpose of the standard being set by the knowledge imputed to a class of persons is to impose a higher standard on persons in that class. It therefore creates a floor but not a ceiling on the level of knowledge so that subjective knowledge can raise the standard. However, lack of actual knowledge cannot lower the standard or exclude liability which would be imposed based on the standard generally imposed."

Reasonable Foreseeability - The Decision

10. The Judge found on the facts that Mrs Kane did not have actual subjective knowledge about the risk of damage to the Khans' property from her trees.

11. However, on a close analysis of the facts, he found that a reasonably prudent landowner would have been aware of the real risk of damage from the Lawson Cypress hedge but not the oak tree.

12. So, the Judge gave judgment for the Claimant for the damage caused by the Lawson Cypress hedge.


13. This important decision is significant for private individual owners of domestic properties and their insurers.

14. In part, because of the ABI Domestic Subsidence Agreement, cases against private individual owners of domestic properties do not frequently come before the Courts.

15. Further, a misconception has developed that, if a private individual owner of a domestic property can assert that she does not have actual subjective knowledge of the risk of tree root subsidence damage from her trees (or generally), she is then immune from claims against her for such damage caused by her trees.

16. This judgment makes clear that the starting part is the objective test of what would be reasonably foreseeable to a reasonably prudent landowner in the Defendant's position.

17. Thus, liability for tree root subsidence damage can be established against a private individual owner of domestic property despite the individual’s lack of actual subjective knowledge of the risk.

Daniel Crowley of 2 Temple Gardens acted for the successful Claimants instructed by Kennedys.

For further information of a copy of the Judgment please contact the Clerks at 2 Temple Gardens on 020 7822 1200 or This email address is being protected from spambots. You need JavaScript enabled to view it.

[1] The claim against LB Harrow who owned land to the left of the Khans' property was settled before trial.



Kennedy v Bournemouth Borough Council, 17.09.12, Bournemouth County Court

The claimant, C, owned and occupied a property in Bournemouth. The defendant, D, is responsible for a maple tree standing next to the property.

C alleged that in early 2009 the drains to her property became blocked and her garden was flooded. Later that year a survey was carried out showing roots from the tree had encroached into the drains, causing the blockage. C said she cleared the roots on several occasions.

C said that despite repeatedly notifying D of the problem they failed to address her complaints adequately. She therefore sought damages from D, alleging nuisance and negligence. Her claim included reimbursement of the costs of repairing and restoring her property.

C's allegations included that D permitted a tree to be planted which was unsuitable for the area, that they failed to carry out proper measures to protect the surrounding drainage, and failed to prevent the roots from encroaching into the drains to her property.

C also applied for an injunction requiring D to carry out works to prevent to roots from blocking her drains.

D denied liability. They said, among other things, that roots will not damage drains but they can grow into drains through existing cracks caused by other means. D denied the tree constituted a nuisance or a hazard.

The court held that by the spring of 2009 it was reasonably foreseeable to D that the maple tree's roots could cause blockages to the drains to C's property. D was then under a duty to consider what, if anything, would be reasonable to do about this, having regard to the amenity value of the tree and the cost of dealing with the problem.

The court noted that local authorities are responsible for thousands of trees and that expenditure has to be prioritised. Ordering this maple tree to be felled due to a blocked drain would, the court held, be a disproportionate response.

The court held that the roots did not cause cracks in the drains. The owner of a property is primarily responsible for closing gaps in their drains and this would be the most effective way to solve the problem. The claim was dismissed.

Comment: The council defended this claim for damages for root encroachment to drains, citing the recent judgment in Berent v Family Mosaic Housing (Court Circular, September 2012). In that case, the Court of Appeal held that if a tree creates a 'real risk' of property damage, consideration should be given to what action, if any, should be taken to address that risk. It might be appropriate to take no action if the risk of damage is reasonably assessed as very low. In this claim, the court also supported the council defending it from a costs perspective, accepting that, in the current economic climate of strict financial constraints, care must be taken to prioritise expenditure; had it not defended the claim there was the risk of the floodgates being opened to require councils to deal with thousands of trees for which they are responsible.

A Tree Manager’s Perspective by Jake Tibbetts

This is a very important and welcome decision regarding alleged subsidence claims involving trees. This case re-emphasises how the law should be applied, and sets a positive precedent for lower courts (who decide the majority of these claims). It also goes someway towards rebalancing the law’s view on trees and reasonableness between 'neighbours'. As the manager of Islington’s Tree Service, I thought it important to give my perspective on the outcome of this case.

I believe that this case could result in reducing significantly the numbers of subsidence claims and the value of those claims against councils who manage trees in a reasonable manner. Tree owners can now argue that they are not liable for damage that has occurred prior to them being made aware that damage has occurred, solely on the basis of a potential risk. In this case, it was only when the potential risk became a real risk that the liability for damage passed to the tree owners.

This judgement recognises the importance of urban trees and the social benefit that they bring. More importantly it clarifies what foreseeablity actually means. This decision moves the perception away from the position that a tree on clay soil near a building equals a “reasonably foreseeable” risk, as has previously been presumed.

In this case all of the damage (some £200,000) occurred prior to Islington Council being informed that there was damage or that the trees were implicated in that damage. Once Islington Council were presented with evidence, we felled two street trees and also allowed for a tree with a Tree Preservation Order (TPO) on the neighbouring property to be removed. Mature plane trees grow on clay soil in this part of the borough, but we do not have a local history of subsidence cases. The claimants argued that it was reasonably foreseeable that the damage would occur (because there were trees on clay soil near buildings) and therefore we should be found liable for all of the costs.

The trial court found that neither Islington Council nor Family Mosaic (who owned the neighbouring property) could reasonably be expected to foresee that their trees might pose 'a real risk' of causing damage to the property until they had been notified that the property had suffered damage, and reasonable evidence had been provided. Until that point we had satisfied our duty to eliminate or minimise potential nuisance and could therefore not be held liable for prior damage, as we had acted reasonably.

This case does not change the situation for damage that occurs after tree related subsidence has been identified as the cause, or in other words when a potential risk has become a real risk.

How we manage trees was also looked into. The argument that 'pruning does not work' damaged the claimants case as the judge was faced with an interesting dilemma – if pruning does not work, what can a reasonable owner do to manage their trees? This argument promotes the notion that the only way to remove the risk of subsidence is to fell all trees near a property on clay soil! This is a disproportionate and unreasonable response which would result in the “desertification” of the urban environment.

What do tree managers need to do in light of this case? I believe it remains critical that we assess our trees, our claims history, our soils, and from that knowledge identify areas which we consider present “real risk”.

Tree managers must identify areas where they have a number of claims, or “hotspots”, and adopt appropriate management regimes, based around this understanding.

Crucially, the judgment does not go as far as to say that tree owners can simply wait until damage occurs and then maintain implicated trees.

This approach would fail to take account of the real risk that a tree might pose. However, where you have determined that there is low risk, in some areas, it may be appropriate not to prune at all.

The other area that this judgment reinforces for me is that reasonableness between neighbours is a key factor.

At all stages of the claims process, and through the management regimes we set up, tree managers need to be able to demonstrate that they have been reasonable in their approach. If we can do this, as previously mentioned, we should be able to see the number of claims and the amount we pay out for subsidence cases reduce drastically.

Seeing the wood for the trees - Article by Clyde & Co

The Court of Appeal confirms that when assessing whether there is a ‘real risk’ of tree related subsidence damage, one must consider whether the relevant trees present a risk, the nature and extent of which imposed upon the owner a duty to take preventative or remedial action over and above any regime of tree management already in place.

The Court of Appeal on Friday 13 July 2012 handed down its judgment in the matter of Berent v Family Mosaic Housing and London Borough of Islington [2012] EWCA Civ 961, and dismissed the Claimant’s appeal.

The claim was advanced on the misapprehension that mere proximity of trees to a building equated to a reasonably foreseeable risk of damage. Both the trial judge and now the Court of Appeal found that there was no ‘real risk’ of reasonably foreseeable damage from the adjoining trees.

The Trial Judge, His Honour Judge Wilcox sitting at the Technology and Construction Court, dismissed the claim finding that prior to damage occurring to the Claimant’s property, neither Defendant could have appreciated that there was a ‘real risk’ that their trees would cause damage. The Claimant’s interpretation of the test of ‘reasonable foreseeability’ in that where a building is within influencing distance of a tree there was a risk of damage, lead the trial judge to say obiter that:

“[Islington] mindful of its obligation under Town and Country Planning Acts and the preservation of such amenities as a treed environment could not reasonably contemplate the desertification of such a neighbourhood by wholesale tree felling to avoid the risk of damage. Such an approach it seems commended by the Claimant almost gives rise to strict liability” [emphasis added].

The obstacles to the Claimant succeeding on her appeal, required her to show either (i) that the trial judge was wrong to find that Islington had in place a prudent regime of pruning or (ii) that Islington should have had a cyclical pruning policy thereby showing an alternative to wholesale removal or the ‘desertification’ the trial judge referred to. Had she overcome those hurdles, she would still have needed to persuade the Court of Appeal that the judge’s findings on causation were incorrect.

The Claimant had pleaded that the Defendants had failed to ‘pollard, crown or otherwise manage or control the growth’ of the implicated trees. However, the evidence of her arboricultural expert, Mr Kelly (the co-author of a paper entitled “Tree related subsidence: Pruning is not the Answer”), as found by Lord Justice Tomlimson, “did not support the Claimant’s pleaded case insofar as that alleged a failure properly to manage trees by pruning prior” [to the damage occurring]. The expert arboricultural evidence had not identified the implicated trees as posing a greater risk than others, or that they should have been subjected to a regime other than the one adopted, or indeed that pruning would have eliminated or minimised the risk in any event.

The Court of Appeal reiterated that a balance needed to be struck when assessing the reasonably foreseeable ‘real risk’ of damage and the inter- related enquiry of what it is reasonable to do in light of that risk. Ultimately, it may be reasonable to take no steps to eliminate an unlikely risk.

The Court of Appeal again highlighted that a further factor to be balanced in this process is the ‘social utility’ of the act which leads to the risk. Had the Claimant been correct, and that trees which were merely proximate rather than ‘a real risk’ needed to be felled, this would be to ignore the social and amenity value of trees.

What can be taken from this decision?
In this matter the Claimant’s property is situated on a road in which there are 276 trees and approximately 300 properties. The properties are of

a similar age and similar distance from the trees and given the age of the properties, it was likely that the properties had shallow foundations. The difficulty for Islington was to assess which of the properties was likely to be damaged and whether there was ‘a real risk’ of damage being causes to a particular property by a particular tree.

The decision is of considerable importance to local authorities and housing associations managing their tree stocks. It confirms that simple proximity of a tree to a building does not elevate the risk of damage from being a potential to ‘a real risk’ of damage. An assessment needs to be made as to whether there is a ‘real risk’. Factors that should be considered include whether there have been previous claims in the vicinity and any other factor that might mean that a tree poses ‘a real risk’. The importance of frequent and severe pruning of trees identified as ‘a real risk’, prior to damage occurring, is again highlighted. However, where the reasonably foreseeable risk of damage is small, it is reasonable to match a pruning regime to the risk, and in some possible scenarios, not to maintain at all. The social benefit of ‘a treed’ environment was highlighted, in that it would not be reasonable to fell all trees that pose a risk (but not ‘a real risk’) to eliminate or minimise that risk.

Tree owners are advised to assess their stock and focus works on the trees assessed as posing ‘a real risk’

Kal Sandhu of Clyde & Co acted on behalf of Islington in both the trial and the appeal. He was instructed by Zurich Municipal, who supported Islington’s stance that the risk of damage was not reasonably foreseeable.

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