Where an architect or engineer specifies a new product on a manufacturer advice and it proves unsuitable, is the designer liable?

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Where an architect or engineer specifies an unfamiliar product after receiving a manufacturer's advice, and the product later proves unsuitable, is the designer liable to the client?

Untried materials, the duty to warn and forming a view

Specifying a novel product a manufacturer recommends can leave the designer exposed if it fails. Whether the architect or engineer is liable turns on whether it warned the client and formed its own view of the product.

Quick answer

Yes, potentially: a designer may specify a new or untried product, but it must warn the client specifically, obtain express approval, and either satisfy itself of the product suitability or advise the client to take specialist advice; specifying a novel product silently, on a manufacturer assurance, exposes the designer to a negligence claim if it fails

An architect or engineer can be liable to the client if a new product it specifies proves unsuitable, but liability turns on whether the client was warned. Using an untried material is not in itself negligent, because the industry must be able to progress, but a designer venturing into untried materials should warn the client specifically and obtain express approval. Nor can a designer escape by pleading ignorance of the product: part of its expertise is to gather information about materials it does not know and to form a view, and if it cannot form a reliable judgment it must tell the client and advise it to take other advice. Relying silently on a manufacturer's assurance, and specifying a novel product that then fails, exposes the designer to a negligence claim. Warn, obtain approval, and either satisfy yourself or send the client for specialist advice.

Untried materialNot negligent in itself; the industry must be able to progress
But warnWarn the client specifically and obtain express approval
IgnoranceNo defence; the designer must form a view or advise other advice
Manufacturer assuranceNot enough on its own; use your own expertise
Failure to warnExposes the designer to a negligence claim
Section 1

The problem

An architect or engineer, pressed by planning, environmental or budget constraints, specifies a new product a manufacturer says will meet the requirement. The product has no track record. It later proves unsuitable and the works fail. Is the architect or engineer liable to the client for the loss, having relied on the manufacturer, or does the risk of a novel product fall elsewhere?

Section 2

Untried materials

Using an untried material is not, in itself, negligent. If designers could never venture beyond the tried and tested, the industry would never progress. But that freedom comes with a condition. A designer that ventures into untried or little-tried materials would be wise to warn the client specifically of what it is doing and to obtain the client's express approval. That was the guidance in Victoria University of Manchester v Hugh Wilson, where an architect's use of a cladding that later failed left it liable for a defective design.

Section 3

Ignorance is no defence

A designer cannot escape liability by pleading ignorance of the product. In Richard Roberts Holdings Ltd v Douglas Smith Stimson Partnership an architect designed a scheme that included a tank lining, which failed; the architect said it had no knowledge of linings and that the client knew it. The court held the architect liable. Part of an architect's expertise is to investigate unfamiliar materials and reach an independent professional conclusion; if it cannot form a reliable judgment, it must tell the client so and advise it to take other advice. Silence, followed by a failure, is negligence.

Section 4

The duty in short

The duty comes to this. A designer may specify a new or untried product, but it must not do so silently. It should warn the client that the product is untried, obtain the client's express approval, and either satisfy itself of the product's suitability using its own expertise or, where it cannot, advise the client to take specialist advice. A designer that specifies a novel product without warning the client, and the product then fails, is exposed to a claim in negligence.

Section 5

Practical steps

1

Treat a new or untried product as a decision to share with the client, not one to take alone.

2

Warn the client specifically that the product is new or untried, and obtain express approval before specifying it.

3

Do not rely on the manufacturer's assurance alone. Use your own expertise to gather information and form a view.

4

If you cannot form a reliable judgment about the product, say so and advise the client to take specialist advice.

5

Record the warning and the approval. The claim usually turns on whether the client was told.

6

As a client, treat a proposal to use a novel product as a point to probe, and record your decision.

Section 6

Authorities

AuthorityCitationWhat it decides
Victoria University of Manchester v Hugh Wilson(1984)An architect using untried materials should warn the client specifically and obtain express approval; a defective design leaves it liable
Richard Roberts Holdings Ltd v Douglas Smith Stimson Partnership(1988)An architect must investigate unfamiliar materials and reach a professional conclusion, or advise the client to take other advice; ignorance is no defence
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Note
This page states the position on the authorities named, as at 13 July 2026. A designer liability for a specified product always depends on the appointment and the facts. This material is provided for educational and professional development purposes only and does not constitute legal advice. Always consult qualified professionals before acting. SCCSI and its contributors accept no liability for reliance on this material.