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procurement guide - design & build (d&b)


A contractor is selected, normally in competition, to Design and Build the project. Tenders are invited on the basis of an "Employer's Requirements" document prepared normally by the client or his consultants.   The Employers Requirements set out the project needs in terms specification, function and performance of the building required and if applicable will also define planning and any other restrictions.

The contractor responds with a set of “Contractor’s Proposals” upon which the tender bids are assessed. Assuming the Contractors Proposals fulfill the employer’s requirements, the lowest bid is often accepted, but this may not be the case because subjective consideration of the overall design and quality of the proposals may be important than cost alone.

Once appointed the contractor employs and is therefore responsible for the design team.

It should be noted that under a JCT form of Design and Build contract, the Employer, unless he/she appoints somebody else, becomes the “Employer’s Agent”.   In the JCT contract this person is assumed to be non-technical and could be the only named party apart from the Contractor – there is often no quantity surveyor, unless the contract is modified.   In most cases the client would be advised to retain the services of his own consultants including a quantity surveyor to protect his interests and act on his behalf.

In many cases nowadays and particularly where the project is of a complex nature or facing difficult town planning procedures, the client often appoints a design team to negotiate planning, prepare preliminary designs and specifications and a detailed design brief before seeking Design and Build proposals from contractors – this is referred to by clients as "Develop then Design and Build”, or by contractors colloquially as “Design and Dump”.  

Develop then Design and Build ensures that the client gets a design that works for him and the risk of the final design and construction works is assumed by the contractor.  In some instances and where the employer agrees or requires it, the initial design team can be novated to the contractor.


  • Establishes a fixed lump sum price, subject only to client's required changes
  • Leaves responsibility with the contractor for organising and programming the design team's activities. The client is therefore not responsible for extensions of time in the event that design information is not produced on time.
  • Variations (known as Changes) are normally pre-agreed and the client has the opportunity to instruct or otherwise, knowing the full consequences in terms of cost and time.
  • The risk for unforeseen circumstances lies with the contractor.
  • Gives single point responsibility


Provides the client with arguably a less sophisticated building in terms of design detailing than would be the case with other forms of procurement

Gives less control over the work in total and of the costs of any variations required

Can be difficult in certain instances to precisely define the standards and quality of design required

Depending on the risks imposed on the contractor at tender stage can result in a higher contract value than would otherwise be the case


Appropriate where the client requires a firm lump sum price and where the required standards and quality can be easily defined before tenders are sought.

For more control over quality and cost, this procurement route can be used in a "Develop then Design and Build" form where the client's design team initially negotiates and obtains planning permission, prepares outline designs, specifications and a detailed brief for the Employer’s Requirements, particularly where more   complex buildings are required under this procurement method.  In some cases the employer’s design team is required to be novated to the contractor after obtaining planning permission.

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