Design and build procurement route

Key takeaways:

The Design and Build (D&B) procurement route is a project delivery method where a single contractor is responsible for both design and construction. This approach streamlines project management, often leading to faster completion and better cost certainty. It is the most commonly used procurement method in the UK, accounting for over 50% of projects. While D&B offers a single point of responsibility, it can limit client control over design details. It is ideal for projects where speed, efficiency, and cost control are priorities, but may not suit those requiring highly customised design input.

[edit] What is the design and build procurement route?

Design and build can be seen as giving a single point of responsibility for delivering the entire project. Some clients, however, consider it is only appropriate for simple projects, where design quality is not the main consideration.

The traditional procurement route was historically the most commonly used procurement route, but there has been an increasing trend for contractors to take a more significant role in setting up projects, making appointments and managing the entire project process. This began with the introduction of design and build, which became popular in the 1980s.

The Procurement Trends Report, published by Ryder Levett Bucknall (RLB) in 2024, found that 67% of projects now use design and build forms of contract, the highest proportion recorded since RLB's survey began. This builds on the trend identified in RLB's March 2022 survey, in which design and build accounted for 54% of projects, and confirms design and build as by far the most commonly-used procurement route in the UK.

The employer gives potential contractors their 'employer's requirements' setting out what they need from the project, and the contractors respond with 'contractor's proposals', which include a price for the works.

The contractor can either be appointed to carry out all of the design work, or if the client wishes to have greater influence over the design, a concept design and outline (or performance) specification can be prepared by a consultant employed by the client, and then the contractor is appointed to complete the design and carry out the construction.

Design and build contracts can be awarded on a fixed price, lump sum basis, but price certainty is then dependent on not making any subsequent changes as these could prove to be expensive (as prices charged by the contractor for those changes will not be subject to competition).

It is very important therefore that the client gives a great deal of consideration to the preparation of the employer's requirements, and if they have not appointed their own design team, they may wish to appoint independent client advisers to help them do this. Similarly, if any designers appointed by the client are novated or switched to work for the contractor, the client may then wish to appoint independent client advisers to review contractor's design proposals, administer the contract and monitor works on site.

There are two main types of design and build:

In the single-stage process the contractor is appointed under a single agreement to undertake the design and then construct the works. Single-stage tendering is used when all the information necessary to calculate a realistic price is available when tendering commences.

In a two-stage process the contractor is first selected on the basis of a fee, preliminaries, overheads and profit. They then work with the design team (who may be employed either by the contractor or by the client at this stage) to develop the design, on the basis of which a fixed price is negotiated for the second stage; construction, when the design team may be novated to the contractor if the contractor does not already employ them.

The design and build procurement route should be used:

Where there is a need to make an early start on site – as design and construction can overlap.
Where the client wishes to minimise their risk – as they have no responsibility for design.
For technically complex projects which can benefit from the contractor's expertise in the design stage.
Where the employer does not want to retain full control over the design development.
Where the client wishes to have a single point of responsibility.

Advantages of the design and build procurement route include:

Disadvantages of the design and build procurement route include:

The client may find it hard to prepare a sufficiently comprehensive brief to ensure the design meets their requirements.
The client has to commit to a concept design early in the project development.
Variations from the original brief can be difficult and expensive to arrange.
It can be difficult to compare tenders and determine if they offer value for money.
Ease of fabrication, speed and low cost may be prioritised by the contractor above aesthetic quality.