Deep Excavation Next to a Neighbour's Boundary Wall
A four-storey mixed-use building is being built in Kandy with a basement 3.2 m deep. The site boundary is a shared wall with a 60-year-old two-storey house. Three weeks after excavation, the neighbour reports diagonal cracks 4–8 mm wide in the rear wall and a sticking door. The neighbour's lawyer sends a letter alleging trespass, nuisance and loss of support, and demands that all work stop. No pre-construction condition survey was done. The contract is a lump-sum building contract with bills of quantities; the architect is the contract administrator and has no structural engineer on the team. The contractor says the cracks are pre-existing and refuses to pay for a survey. The employer wants the basement finished on programme and asks the architect to 'write a letter protecting us'.
1. What legal basis, if any, does the neighbour have, and what is the architect's proper role?
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The neighbour's claim rests on three overlapping bases. First, the right of support: land and buildings have a right not to be deprived of natural support by excavation on adjoining land, and the excavating owner must take reasonable steps to avoid damage. Second, nuisance: vibration, settlement and dust can amount to unreasonable interference with use and enjoyment. Third, negligence: the contractor owes a duty to take reasonable care to avoid foreseeable damage. The Party Wall Ordinance may also apply to the shared boundary wall; whether it does depends on the wall's status and the local authority area, so this must be checked rather than assumed. Trespass is a weaker claim unless the excavation or scaffolding actually entered the neighbour's land. The architect's position is not that of a lawyer or structural engineer: the architect should not give a legal opinion, but must act on the contract and coordinate the investigation. The letter should not 'protect' the employer by denying the cracks without evidence; that could later be used against the employer.
2. What immediate and investigative steps should the architect take?
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Immediate steps: (1) advise the employer in writing that the allegations are serious and that work in the affected zone should be suspended until a structural engineer has inspected; (2) appoint an independent structural engineer to carry out a condition survey of the neighbour's property and the excavation support; (3) ask the contractor for its method statement, temporary works design, monitoring records and insurance details; (4) photograph and record the cracks jointly with the neighbour, if possible; (5) check whether the contract requires the contractor to indemnify the employer for damage to adjoining property and whether notice to insurers is required; (6) respond to the lawyer without admitting liability, stating that the matter is being investigated. The reasoning is that early evidence preserves the employer's position and may show whether the cracking is pre-existing. It also meets the employer's legitimate need for a response without the architect exceeding professional competence.
3. How should responsibility be allocated, and what should the architect record for the contract?
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Responsibility should be allocated on the facts, not by writing a protective letter. If the contractor failed to use reasonable care, failed to support the excavation, or ignored monitoring, the contractor bears the cost under its indemnity and insurance. If the employer's design or instructions caused the problem, the employer bears it. The architect's role is to administer the contract: issue instructions, assess whether a variation or suspension is required, and record time and cost effects. Any settlement with the neighbour should be handled by the employer's lawyer and insurer. The architect should also review the absence of a pre-construction survey: this is a lesson for the next project, because without a baseline it is difficult to prove causation. The employer should not be told that a letter can eliminate liability; liability follows the evidence.