Highlighting the line of duty on building designs

Engineers have a duty to act with reasonable skill and care, but that doesn’t necessarily mean their designs are fit for purpose under the law, says CNS Consult’s Vincent Fogarty, who summarises designers’ legal obligations

UK law provides that, in the absence of any written terms and conditions to the contrary, a professional designer has a duty to act with reasonable skill and care. This duty is implied in all contracts for service by virtue of the Supply of Goods and Services Act 1982.

There is a common-law test for negligence, which states that a professional person is not negligent if they carry out their work to the same standard as another reasonably competent member of their profession would have done.

The Bolam Test1 established that, where special skill and competence are involved, it is not necessary for the professional consultant to possess the highest skill, provided their views or actions accord with those of a responsible body of opinion of that profession. So if a consultant can show they acted in accordance with the usual practice and professional standards for their particular business, current at the time the design was carried out, they will escape liability.

Fitness for purpose

A fitness-for-purpose obligation imposes a higher duty because it is an absolute obligation to achieve a specified result, a breach of which does not require proof of negligence. This duty stems from the Sale of Goods Act 1979, which imposes implied terms on any seller acting in the course of business that the goods supplied will be of satisfactory quality and – where the purchaser makes known any particular purpose – are reasonably fit for their intended use. In construction, for example, this means a contractor is effectively guaranteeing that the components and finished building will be fit for their intended purpose.

The distinction between these two levels of responsibility is important because professional indemnity insurance will cover the holder only in the event of a claim arising out of their professional negligence – for example, a failure to exercise reasonable skill and care. This leaves the designer uninsured against a claim for breach of a fitness-for-purpose obligation.

Without using the phrase ‘fitness for purpose’, absolute obligations may still be imposed. A common way for this to be achieved is to insert a requirement for the consultant to warrant that the completed works shall comply with the employer’s requirements and/or any performance specification. Such wording commonly follows a reasonable skill and care obligation, which may lull a consultant into a false sense of security. For example, an amended clause may read ‘the skill, care and diligence to be expected of a properly qualified and competent architect or engineer’.

Duty to warn and Grenfell

The Grenfell fault question is subject to an ongoing police investigation, but it could be reduced to who possessed the awareness of the fire risk associated with the cladding, and who ought to have had that awareness and an obligation to warn? If a party did recognise an error, there could be a duty to warn.2

English law is void of a general duty to warn, but circumstances may arise in which such a duty exists. There may be a duty of care in tort to warn a third party of a known danger, and – where there is a contract – a duty to warn may extend to dangers of which a party ought to have been aware, particularly where a potential threat to the wellbeing of people is extant, as in Cleightonhills v Bembridge Marine3, when Akenhead J said: ‘An obligation to ascertain or check whether designs or works are safe for human beings, his or her tortious duty of care may extend to warning or advising about inherent dangers of which he or she should have been aware.’

This obiter may prove to be relevant in the context of Grenfell and may determine who ought to have had a duty to warn on design decisions that were, perhaps, erroneously made.


  1. Bolam v Friern Hospital Management Committee [1957]
  2. Building a Safer Future, December 2017, Dame Judith Hackitt, Cm 9551, Summary of the report, Interim report. The review has not been charged with investigating the specific circumstances at Grenfell.
  3. Cleightonhills v Bembridge Marine Ltd & Others. [2012]

Vincent Fogarty is a director at CNS Consult