What this means for property owners, developers, and professionals dealing with ground movement and defective construction.
Background
A recent High Court judgment — Mallas v Persimmon Homes Ltd [2025] EWHC 2581 (TCC) — shines a spotlight on the consequences of getting foundation design wrong.
Mr Ioannis Mallas purchased a newly built Persimmon home in Reading in 2015 for £649,495. Within months, cracks began to appear across the walls and ceilings. What at first looked like typical “settlement cracking” turned out to be much more serious.
The home had been built on shallow trench strip foundations over London clay, on land previously occupied by mature trees. When those trees were removed, the ground rehydrated and heaved, causing structural movement.
The Legal Battle
Mallas sued Persimmon for breach of contract and under the Defective Premises Act 1977. Persimmon admitted liability — its design failed to take proper account of the clay soil and historic tree removal — but argued that the problem could be fixed by underpinning, rather than demolishing the property.
Mallas wanted a complete rebuild, claiming that the timber frame might have hidden damage, the developer lacked “as-built” drawings, and the house might contain other undiscovered defects.
The Judgment
Deputy High Court Judge Alan Bates ruled firmly in Persimmon’s favour on the extent of the remedy:
- Underpinning, not demolition, was the appropriate and proportionate solution.
- There was no evidence of damage to the timber frame or other unseen structural failure.
- Missing “as-built” drawings did not make the building unsafe or unrepairable.
- A total rebuild would have been disproportionate and unreasonable.
However, Persimmon was still ordered to pay substantial damages:
💷 £385,543 for remedial works (including underpinning and associated repairs)
💷 £27,700 for alternative accommodation during works
💷 £10,000 for stress and inconvenience
Total: £423,243
Key Legal Points
- “Cost of cure” damages apply only where the remedial approach is reasonable and proportionate.
- Demolition and rebuild will rarely be justified unless the property is dangerous or structurally unsound.
- Developers can breach both contractual warranties and the Defective Premises Act even if the home is still habitable.
- The court reaffirmed that evidence, not speculation, determines the extent of loss.
Tree Law’s Perspective
For anyone dealing with clay soils, tree removal, or foundation movement, this case is a powerful reminder that:
🌳 The relationship between trees and soil is critical — especially on shrinkable clay.
🏗️ Ground investigation and foundation design must account for both existing and historic vegetation.
💬 Claims for subsidence or ground heave often hinge on whether the builder or designer properly understood that risk.
📑 And when things go wrong, proportionate repair — not replacement — is usually the court’s preferred path.
Why It Matters
Tree-related ground movement remains one of the most common and complex sources of property damage. Cases like Mallas v Persimmon show that even large developers can fall foul of basic geotechnical principles.
Whether you’re a homeowner, insurer, or local authority, it reinforces the need for early expert advice — and for design teams to understand the long-term soil–tree–structure dynamics before a spade hits the ground.
Tree Law specialises in resolving disputes where trees, ground conditions, and the law meet — from root-induced subsidence to heave and foundation failure. For tailored legal support, contact our team.
