Charlton & Anor v Northern Structural Services Ltd

A structural engineer advising on building movement must investigate the nature of the subsoil, foundations and existing damage sufficiently to assess risks from tree-related desiccation and rehydration. Where mature trees have caused desiccation, immediate removal may create a foreseeable risk of clay heave. Reasonable advice may require phased pruning, height reduction and root curtailment, supported by appropriate specialist advice. A failure to identify and explain that risk may cause liability for subsequent structural damage and diminution in value. A diminution claim may be valued at a later date where that date is reasonable, the loss remains directly linked to the breach, and the delay is not attributable to a failure to mitigate.

Mr and Mrs Charlton claimed damages from Northern Structural Services Ltd for negligent structural engineering advice given when they were buying a house. The defendant advised that historic cracking was caused by cavity tie corrosion and recommended removing large trees near the property. The claimants removed the trees, after which further cracking and structural movement developed. They alleged that the advice failed to identify clay subsoil, the risk of rehydration and clay heave, and the need for a gradual tree-management programme.

The court determined breach of duty, causation, the appropriate valuation date for diminution in value, and the recoverability of associated expenditure and general damages.

1. Liability. Judgment was entered for the claimants. The court found that the cracking and structural movement between 2000 and 2002 resulted from rehydration and heave of clay previously desiccated by mature Leylandii trees.
2. Scope of duty. The engineer’s instructions required investigation of the historic movement, the proximity and effect of trees and roots, and the future risk to the structure. Reasonable skill and care required investigation of the subsoil, its moisture condition, the possibility of shrinkage or swelling, and the foundation depth. The engineer’s assumption that the subsoil was non-shrinkable, without trial holes or supporting evidence, was negligent.
3. Tree-removal advice. Advising immediate removal of all large trees without investigating ground conditions was inappropriate. The safer course was a phased programme of pruning, lopping, height reduction and root curtailment, with arboricultural advice, to reduce water extraction gradually and avoid rapid rehydration and clay heave.
4. Subsequent inspections. On later visits the engineer failed to recognise the significance of fresh cracking, wet subsoil and tree-root evidence, and failed to identify the continuing risk of clay rehydration damage. Those failures also fell below the required standard.
5. Causation and loss. The claimants had relied on the advice and established that a gradual tree-management programme would have avoided the cracking and resulting stigma. The diminution in value could reasonably be assessed using 2007 values because the prolonged uncertainty was materially linked to the defendant’s negligent advice and denials of liability. The court awarded £20,000 for diminution in value, £1,000 for crack repairs, £2,882.71 for unnecessary tree-removal equipment, £1,411.38 for pre-litigation expert fees, and £5,000 for inconvenience and distress. Drainage replacement costs were not recoverable.
6. Order. Judgment was entered for £29,294.09. Interest and costs were to be agreed, with directions for written submissions if agreement was not reached within 14 days.