Malewski & Anor v London Borough of Ealing

Liability for tree-root subsidence depends on the overall evaluation of the scientific and factual evidence. Relevant considerations include the depth and type of roots, the depth and severity of desiccation, the location and characteristics of the trees, monitoring evidence, remedial works and comparable damage. An apparent absence of damage nearer a tree does not necessarily exclude that tree as the cause, since localised anomalies may occur. Where the evidence establishes that a highway authority’s tree was the sole or predominant cause of subsidence, the authority is liable in nuisance for the resulting damage. A claimant is not subject to a reduction merely because vegetation within the claimant’s ownership was a possible but immaterial cause.

The claimants owned and occupied a semi-detached house adjoining another property. Subsidence damage affected both properties during 1994 to 1996. The damage resulted from desiccation and shrinkage of London Clay beneath the foundations.

Two potential sources were advanced. The first was a mature oak situated in the highway and owned or controlled by the defendant highway authority. The second was vegetation in the front gardens of the claimants’ property and a neighbouring property. The parties relied on engineering and arboricultural evidence, borehole samples, crack monitoring, level surveys and evidence of damage to nearby properties.

The central issue was whether the oak or the other vegetation caused the relevant desiccation and subsidence. The parties agreed the amount of damages if the defendant was liable.

1. Liability. The claimants succeeded. The predominant cause of the desiccation and subsidence was the defendant’s oak tree. The defendant was therefore liable in nuisance.
2. Assessment of causation. The evidence had to be considered together and in the round. The court placed particular weight on the severe desiccation to a depth of 4 metres, the predominance of oak roots at depths between 2 and 2.5 metres, the characteristics of oak rooting, the location of the damage, the crack-monitoring records and the nature of the underpinning.
3. The plum and Leyland cypress trees were less capable of producing deep desiccation. Their removal or substantial reduction in 1995 meant that they could not explain the significant cracking that continued in 1996. The monitoring evidence therefore provided a control indicating that the oak remained the predominant influence.
4. The absence of damage at the part of the properties nearest to the oak did not exclude it as the cause. Desiccation may be affected by localised topographical features, temperature differences, water courses, variations in the water table and leakages. The level surveys did not materially support either side and were set aside for causation purposes.
5. The court adopted the description in Deleware Mansions Ltd v Westminster City Council [2001] 3 WLR 1019 of the relevant damage as impairment of the load-bearing qualities of the sub-soil. The evidence showed that impairment was caused by oak-root desiccation.
6. The parties agreed damages of £55,246, together with interest, and general damages of £1,500 for each claimant. £1,000 plus interest was payable to the claimants in respect of the policy excess they had funded.