Practical Law

It is commonly thought that homeowners are not liable for damage caused by the roots of trees on their property, because they lack the necessary degree of foresight. However this is no longer correct. In a decision of some significance, Ramsey J in Khan and Khan v Harrow Council and Sheila Kane has held that homeowners can be liable to neighbours for damage caused by tree root encroachment, even if they were personally not aware of the risk of damage.

The facts in Khan v Kane

In July 2001, Mr and Mrs Khan bought a house in Stanmore, Middlesex. Next door lived Mrs Kane. In the garden of Mrs Kane’s property was an oak tree ten metres from the Khans’ house and a ten-metre tall cypress hedge on the boundary only half a metre away.

In 2006, the Khans noticed cracks to their property. They contacted insurers who carried out initial monitoring. In July 2007, they produced a report identifying the cypress hedge as potentially being a significant factor. The report recommended that the cypress hedge be cut back so as to leave five meters clearance. This report was not seen by Mrs Kane. She first became aware that vegetation on her property might be causing damage in June 2009 when she received a letter from the Khans’ solicitors. The letter recommended that the cypress hedge be removed. Mrs Kane did this without delay.

After further monitoring the Khans’ solicitors wrote saying they believed that the oak tree was also a cause of the damage. This was also removed after the necessary permission was obtained from the local authority (it was a protected tree).

The Khans subsequently sued Mrs Kane for the damage to their house which occurred before Mrs Kane was told that such damage was being caused.

The judgment

The Khans argued that the risk of damage from the cypress hedge and oak tree was reasonably foreseeable to Mrs Kane before 2006, and that she should have taken pre-emptive preventative steps. Mrs Kane denied that she knew there was any risk of damage.

Ramsey J found for the Khans. He:

• Accepted that Mrs Kane actually did not know of the risk, but held the reasonably prudent landowner in the position of Mrs Kane should have been aware of the risk of damage caused by vegetation on her land. This awareness was not just a general awareness of tree root damage, which could be obtained through the media, but also the particular features of the trees in question.
• Held that the size and proximity of the cypress hedge to the Khans’ house was sufficient to put Mrs Kane on notice of a real risk of subsidence damage, rather than the mere possibility of such damage. However, he did not think that there was any particular feature of the oak tree that would have put Mrs Kane on notice that it presented a real risk of damage.
• Found that Mrs Kane was in breach of her duty in failing to remove the cypress hedge. He reduced the Khans’ damages by 15% because they were contributory negligent in not warning Mrs Kane.

Potential consequences of the judgment

While Ramsey J was at pains to confine the judgment to its facts, I believe his decision may have wider effect.

In practice, neighbour-neighbour tree root subsidence claims are not brought where the respective insurers are signatories of the ABI Domestic Tree Root Agreement (DTRA). However, the Khan v Kane judgment opens the door to claims against homeowners where the insurer is not a signatory, or where the homeowner is not insured. Moreover, there is no reason why councils and housing associations (who are often defendants in tree-root subsidence claims) cannot bring contribution proceedings against the residential homeowner. Insurers will now need to consider whether premiums should increase.

Ramsey J expressly stated that it was important that the standard imposed on landowners was not that of the reasonably prudent arboriculturalist, but it is difficult to see how a landowner can discharge his or her duty without that specialist knowledge. He held that as the cypress hedge was so close to the property, Mrs Kane ought to have appreciated the risk of damage. But what if they were slightly further away? Or slightly less imposing? What if the oak tree was slightly nearer? How is one supposed to make the judgment about whether vegetation poses a risk? To avoid the risk of liability the only safe course may be for the landowner to instruct a specialist.

Was the judgment correct?

Mrs Kane was found liable because she failed to appreciate that the cypress hedge was the source of a real risk of damage to the Khans’ house.

Is this correct? That finding relies upon the size and proximity of the cypress hedge as the reason for there being a real risk of damage. However, this issue was specifically considered (at first instance) by HHJ Wilcox in Berent v Family Mosaic Housing Association and London Borough of Islington. He said that:

“An attempt by the Arboriculturist Association to develop a computerised model capable of assessing the future risk of subsequent damage to buildings was abandoned because it was demonstrated as being impossible to predict. The study involved eminent mathematicians, computer experts and arboriculturists.”

On the facts of Berent (upheld by the Court of Appeal), the local authority was not put on notice of the risk of damage from tall poplar trees standing only 12 metres from the property. It is difficult to see why Mrs Kane should be in a worse position than a local council.

The problem is that to appreciate there is a risk, one must know something about the water-uptake characteristics, spread pattern and depth of the roots in question. Without that, then the risk of damage is only a mere possibility (which would not result in liability). It is difficult to understand why Mrs Kane was deemed to know any of the characteristics of a cypress hedge.

To illustrate this point, at trial Mrs Kane’s arboricultural expert initially did not believe that the cypress hedge even materially contributed to the damage. If a highly qualified person can think this (and presumably would not have advised that any works needed doing to the hedge), it is fair to ask why Mrs Kane should have appreciated there was such a risk.

The effect of Khan v Kane is that landowners must now be aware that they are potentially liable for damage caused by their trees, even if they themselves do not think there is any risk.

Muhammed acted for the London Borough of Harrow, the claim against which settled before trial.