These 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. D&B 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.
Adisadvantage to some promoters is that they 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 promoters 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.