The Kandy Hillside Plot: A Cut Slope, An Expired Loan, and a Neighbour's Cracking Wall
A client owns an 11-perch plot on a hillside inside the Kandy Municipal Council area. The natural slope across the plot measures about 32°, and a previous owner cut roughly 3 m into it without approval, leaving an unengineered rubble retaining wall 2.4 m high along the lower boundary. Hairline tension cracks have appeared behind that wall since the last monsoon. The client now wants a three-storey house with a basement garage, which requires a further 4.5 m cut and a 6 m high retaining structure. A contractor has already mobilised, no borehole has been sunk, and the client wants the building application lodged next week because the bank's loan approval expires in 60 days. The architect's fee is 4 per cent of an estimated LKR 55 million construction cost, and the client has asked the architect to "use the earlier soil report from the neighbouring site" to save time and money.
1. What must be in place before the architect signs and lodges the building application? Explain the reasoning behind each item rather than listing approvals.
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The architect should treat the neighbouring soil report as background only. On a hillside, residual soil thickness, rockhead and the position of the failure surface can change within a few metres; a report from an adjoining plot cannot support a design for a 4.5 m cut and a 6 m wall. The minimum technical basis is:
- A site-specific geotechnical investigation - at least two or three boreholes taken below the proposed formation level, plus trial pits along the existing wall line, with laboratory shear-strength parameters. This is what allows a slope-stability analysis to be run for both the temporary cut and the permanent condition, including a surcharged, saturated slope.
- A stability analysis and retaining-wall design by a geotechnical and a structural engineer respectively. The existing 2.4 m wall is already showing tension cracks; it cannot be assumed to act as a berm or to survive a 4.5 m cut immediately above or below it.
- NBRO hazard screening. Kandy's hill slopes are mapped for landslide hazard, and the local authority will normally expect the National Building Research Organisation's recommendation where a slope is steep and a cut is proposed. Skipping this is the quickest route to a refusal.
- Drainage and cut-face protection design, because the monsoon, not the excavation, is usually what triggers failure.
Only when these exist can the architect sign drawings that truthfully represent the proposal. The application also needs the structural engineer's certification; the architect's signature does not substitute for it.
2. The client instructs the architect to lodge the drawings anyway and says the contractor will "take care of the slope". How should the architect respond, and what is actually at risk if he complies?
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The architect should refuse, in writing, the same day, and separate the refusal from the client's commercial problem so that it reads as a solution rather than an obstacle. A practical response offers a fast-track: two boreholes can usually be drilled and reported within two to three weeks in Kandy, and the client can request a short loan extension with the geotechnical appointment letter as evidence of progress.
The risks of complying are concrete, not theoretical:
- The application itself becomes a false statement. The architect is the author of the submission. Signing drawings that show a 6 m retaining structure with no design basis misrepresents the proposal to the local authority.
- Disciplinary exposure. The SLIA code of conduct requires competence and regard for public safety; knowingly lodging unsupported drawings is a conduct matter independent of whether anything collapses.
- Criminal and civil exposure if the slope fails. A failure that damages the neighbouring property or injures a worker invites claims in negligence, and the architect's file becomes the evidence. A written record of advice given and declined is the single most valuable document the architect can create at this stage.
- Insurance. Professional indemnity policies commonly exclude unlawful or unapproved works, so the very event the architect most needs cover for may fall outside it.
- The contractor cannot "take care of" a design risk. Temporary works are the contractor's responsibility, but the permanent cut, wall and drainage are the designer's, and the building will outlive the contractor's involvement.
3. Six months later the cut has been made and the neighbour's wall has collapsed after heavy rain. How should responsibility be analysed, and what in the architect's file will matter?
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Responsibility is not a single answer; it is distributed and must be analysed in layers.
- The owner commissioned and paid for the excavation and is the person who physically interfered with the slope. Liability in nuisance and negligence for withdrawing support from a neighbour's land ordinarily attaches to the party who carried out the works.
- The contractor owes duties for the manner of excavation, for temporary support and for following any specified sequence. If the drawings said "excavate in 1.5 m lifts with immediate shoring" and the contractor dug 4.5 m in one pass, that is a contractor failure.
- The architect and engineers are exposed only if the design was deficient or if the advice was not given. The critical question is whether the file shows that the geotechnical and NBRO requirements were raised, in writing, before work started.
The file therefore matters more than the argument. What counts is: a dated letter recommending investigation; the client's written instruction to proceed without it; site instructions on sequencing; the refusal to certify any stage as compliant; and the inspection records. Without those, the architect will be reconstructed as having acquiesced. With them, the architect's position is that a known risk was disclosed and a decision was taken by others. The lesson for practice is that advice declined must be recorded contemporaneously, not reconstructed after a failure.