The periodic certification of design by design consultants is a common method in the ‘design and construct’ procurement market to ensure that the design is proceeding in accordance with the project brief and that construction work is in turn being carried out to that design intent. While this appears to be a straight forward concept, this article considers some of the issues around design certification on projects involving performance based design specifications.

Many design and construct procurement arrangements have the effect of ending any existing contractual relationship between the Principal and the consultants and creating new contractual relationships between the consultants and the Contractor (whether by entering new agreements or novating existing agreements). With the Contractor being the new ‘master’ of the consultants, the Contractor now directs the design consultants in the design development of the project and assumes all design obligations to the Principal under the design and construct contract. While the design obligations are ultimately held by the Contractor, the design work is carried out by the design consultants for the Contractor. With the Principal losing direct access to the consultants, design certification to the Principal becomes an important deliverable of the Contractor. 

All design and construct projects are different and have varying requirements, but commonly each design consultant will progressively certify that, among other things, their design satisfies the project brief, all required inspections and approvals have been carried out/given and all construction work (relating to their discipline) has been carried out in accordance with the design intent of their designs.

Performance based design specifications are sometimes prepared by design consultants for parts of the work forming their initial design. This may be because a particular subcontractor is in a better position to be aware of market solutions and methods that can more cost effectively satisfy the performance which the design consultant wants to achieve or for other commercial reasons. Where performance based design specifications are prepared by design consultants, the key design input is still provided by the design consultant but elements of the design solution rely on the design input of and resolution by the Contractor’s relevant subcontractor.

Where the Contractor’s subcontractors are performing such design functions, the question of who will certify that aspect of the design becomes an issue. From a Principal’s perspective, it would be ideal if the design consultant not only reviewed the designs produced by any of the Contractor’s subcontractors but also certified that those designs are in accordance with the project brief and all laws etc. In reality and not surprisingly however, design consultants are generally unwilling to certify the design work of others. It is generally accepted that design consultants will review shop drawings produced by the Contractor’s subcontractors and approve those drawings as having been prepared in accordance with the design intent of the designs produced by the design consultant (in effect, ensuring the co-ordination of work but not certifying the compliance of the design work of the Contractor’s subcontractors).

Where there are performance based design specifications, if the design consultant does not certify the design work of the Contractor’s subcontractors in relation to their discipline, this exposes a gap for the Principal in the design certification regime, which needs to be filled by the subcontractor itself providing a similar design certificate for their work. In this scenario, what becomes important to a Principal is ensuring that the right entities are certifying the right parts of the design and that there are no gaps in the overall certification of the constituent parts.

The gap issue is obviously of greatest significance in those areas of consultancy discipline which create performance based design specifications requiring a specialist subcontractor of the Contractor to provide a solution based design. The extent of the issue probably correlates closely to the extent to which the design consultants prepare performance based design specifications for their disciplines.

A full and complete design certification regime is important for a Principal because of the reliance that is placed on the certificate and the purposes upon which it is used. It is generally accepted in the design and construct market that such design certificates are procured by the Contractor from the design consultants (and subcontractors where relevant) and provided to the Principal with each claim for payment, at practical completion and at the final claim for payment. The design certificates state and record that in the certifier’s (design consultant or subcontractor if relevant) opinion, the design is compliant and any constructed works are compliant with the design (other than any exceptions stated in the design certificate). In effect, the certificates are provided at the payment ‘gateways’ at a time when it is necessary to consider design compliance of both documentation and construction.

It is however, important to remember that any design certification regime is complementary to and should not replace the market accepted design and construct warranty that should be given by the Contractor to the Principal that the works upon practical completion shall be fit for their intended or stated purpose. Nor does the design certification regime affect the Contractor’s liability for the design provided by its design consultants or subcontractors (subject to any effects such certification has on relevant proportionate liability legislation).

Principals should draw from this article that the design certification regime on projects involving performance based design specifications may require more due consideration, while Contractors should expect that on these projects their design consultants may be asked to provide more involved design certification either in addition to, or combined with, design certification from the Contractor’s subcontractors.