What are the designer's obligations in construction?

The duties of a contractor carrying out design are defined by the scope of work as well as express and implied contract terms, statute and professional obligations.

When reviewing design obligations and potential risk, it is also important to distinguish between the different duties in respect of goods and materials, and services and design.

Details will be set out in the contract terms or may be implied by statute, such as the Defective Premises Act 1972 and Sale of Goods Act 1979. However, employers often introduce further wording regarding unacceptable or hazardous materials.

The contract will usually specify the standard of work required, but if it does not then the works are to be carried out with appropriate skill and care. This is expressed in JCT contracts, for example, as carrying out the works in a 'proper and workmanlike manner'.

When it comes to services and design, the two common duties for a designer, found in most forms of contract, are as follows.

• Reasonable skill and care: to discharge their duty the designer is to act in accordance with the usual practice and professional standards that apply at the time that the design was carried out.

• Fitness for purpose: this is an absolute obligation to achieve a specified result or outcome that imposes a higher standard than reasonable skill and care, and may not be covered by professional indemnity insurance (PII) policies.

Sometimes it is difficult to work out which duty applies. For example, if the scope of the obligation is expressly confirmed to be performing the duties of a designer exercising the appropriate degree of skill and care – which is sometimes expressed as the same standard as an architect or professional – the party carrying out design could be held to the higher fitness-for-purpose standard.

This is because English law imposes a fitness-for-purpose obligation where a non-professional (e.g. a non-architect) has committed to undertaking an activity to the standard of a professional (i.e. an architect).

Even where the obligation is to use reasonable skill and care, it can be necessary specifically to disclaim particular expertise and to tell a client that they need to seek specialist advice elsewhere.

In the context of fire safety, the case of LDC (Portfolio One) Limited v (1) George Downing Construction Ltd and (2) European Sheeting Ltd [2022] EWHC 3356 (TCC) also confirmed that a strict obligation to comply with statutory requirements, including Building Regulations, is not superseded by an obligation to exercise reasonable skill and care.

Case law confirms that even where contracts require 'reasonable skill and care', a competing provision can impose a responsibility that the materials, service or design must be 'fit for purpose'.

That happened in MT Højgaard AS v E.ON Climate and Renewables UK Robin Rigg East Ltd & Anor [2017] UKSC 59, where the contractor found itself responsible for design defects due to wording described in the judgment as being 'tucked away' in a technical document.

This was despite the fact that the contractor had met its obligations to work with reasonable skill and care, and had complied with relevant industry codes.

NEC contracts impose a fitness-for-purpose obligation as default unless option X15, requiring reasonable skill and care, is selected.

In any event, the works information or scope should still be checked to see whether fitness for purpose obligations are imposed in respect of any aspects of design.

• confirmation that the contractor takes responsibility for any design in employer design documents, such as the employer's requirements in JCT contracts
• a lack of provision for time or money remedies for design errors, even if those errors are in documents that were not produced by the contractor, or for discrepancies between the contractor's design and any higher standards in the employer's design
• amendments to wording that the skill and care to be exercised must be the same as that expected of an architect or professional designer; the standard of a building contractor is higher than a general obligation to complete the works with reasonable skill and care and denotes fitness for purpose
• fitness-for-purpose obligations and life-cycle guarantees hidden in the employer's requirements or technical specification documents, which may take precedence over the skill and care obligation in the contract terms, as was the position in MT Højgaard.

Practical tips for managing these common pitfalls include:

• checking whether the contract confirms that the design liability standard requires reasonable skill and care
• avoiding the requirement for fitness for purpose being imposed by the back door, carefully checking specification requirements and technical documents as well as the contract terms
• considering the ability to pass obligations down the contractual line – for example, to design consultants or subcontractors – and recourse to any novated design team where accepting responsibility for employer design
• understanding PII policy requirements and what can and cannot be claimed
• following the golden thread approach of maintaining a comprehensive and consistent record when undertaking design and construction activities, as this will help ensure that the design and as-built condition is clear and documented.

It is possible to manage design risk if contracts and accompanying documentation are carefully reviewed to understand the liabilities to which the parties are signing up, and the design process is then monitored through to completion.