• Persimmon admitted breach for shallow foundations causing structural movement
• The claimant sought full demolition and rebuild; the court ruled this disproportionate
• The appropriate remedy was underpinning and repair, not reconstruction
• Total provisional damages: £423,243
• The judgment reinforces the principle of proportionality in construction defect damages
In Mallas v Persimmon Homes Ltd, the claimant purchased a newly built four-bedroom home in Reading, which soon developed cracking and movement. Investigations revealed that the trench strip foundations were too shallow for the London clay subsoil, particularly after nearby trees were removed - a classic trigger for ground heave and differential movement.
Persimmon accepted it had breached Clause 1 of the building contract (the duty to carry out works in a proper and workmanlike manner) and its statutory duty under section 1(1) of the Defective Premises Act 1972 (DPA 1972). The central dispute was not about liability, but about what was a reasonable and proportionate remedy.
The claimant advanced two schemes involving complete demolition and rebuild. Persimmon argued instead for a piled raft underpinning solution combined with repairs - a more economical and technically sufficient fix. The claimant justified demolition on three grounds: possible latent defects, a lack of 'as-built' drawings, and alleged poor-quality construction. None of these, the court found, were supported by evidence.
Deputy High Court Judge Alan Bates held that demolition was disproportionate and unreasonable. The court reaffirmed McGlinn v Waltham Contractors [2007] - demolition is an 'extreme course' and only appropriate where the building is unsafe or structurally unsound. Once ground movement was stabilised, the cracking was largely cosmetic. The claimant’s 'known unknowns' were not sufficient. The absence of 'as-built' drawings or hypothetical defects did not justify total reconstruction.
The court noted that opening-up investigations could have provided evidence if structural failure was suspected. The court found the property generally fit for habitation under the test in Vainker v Marbank Construction Ltd [2024]. The only unsafe element was the porch, which sat on particularly shallow foundations requiring support. The court preferred Persimmon’s Scheme 3, which involved piling, underpinning, and localised repairs - a solution described as 'robust and technically appropriate.
The court awarded £385,543 for remedial works and related costs; £27,700 for alternative accommodation; and £10,000 aggravated damages, totalling £423,243 (provisional). Claims for stigma, blinds, and additional surveys were rejected.
1. Proportionality remains central - Even where liability is admitted, the claimant must prove that demolition is reasonable. The cost of cure must be objectively fair between both parties, as articulated in Hudson’s Building & Engineering Contracts.
2. Evidence matters - Courts will not accept speculative arguments about possible defects. If a claimant believes structural failure exists, investigative evidence is required.
3. The DPA 1972 continues to evolve - Following BDW Trading Ltd v URS Corporation Ltd [2025] UKSC 21, the extended 30-year limitation period under the Building Safety Act 2022 means historic defects can still give rise to claims - but proof of unfitness remains essential.
4. Cosmetic damage/structural failure - Visible cracking, without more, is insufficient to establish that a home is uninhabitable or unsafe.1`
For developers and housebuilders, this case underscores the importance of proportionate rectification strategies supported by sound expert evidence. For homeowners, it is a reminder that the courts will not order demolition unless truly necessary. Emotional dissatisfaction or incomplete records are not substitutes for proof.
Mallas v Persimmon Homes Ltd reinforces a pragmatic truth of construction law: the appropriate remedy is the one that fixes the problem - not the one that overcorrects it. By rejecting demolition and favouring a technically sound repair, the TCC reaffirmed that proportionality is not merely a principle of cost, but of fairness and practicality.
Holmes & Hills LLP advises developers, contractors, and homeowners on defective premises disputes, adjudication, and court proceedings. For expert advice, contact our Construction Law Team.
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