Design and build contract is contract where contractor is responsible for design as well as construction of the project. Client is only interested in the output of the project, and full responsibility of delivering such type of contracts lies with the contractor. these type of contracts are useful to a promoter who wishes to delegate the whole process of design and construction, or for whom gaining the output of a project
is of more importance than the details of design. They also suit promoters who would not expect to be involved in construction work, such as health or education authorities.
Design and build contracts can offer a price advantage because the contractor can reduce his costs by using easy-to-construct, standard, or previously used designs which suit his usual methods of construction and existing plant.
Disadvantage of design and build contracts is that client lose control over the designs for which they are paying and may thus not get works wholly to their liking. Such contracts should only be used where there is little risk of the promoter’s requirements changing during construction.
Since the contractor is taking on more risks including those of design and buildability, prices will usually be higher than for a measurement contract. Any attempt to achieve a short completion time for a project by use of such conditions may also lead to increased prices and possible overruns of time, as not all of the processes of design and construction can overlap.