Other chapters usually do not mention the existence of professional consultants, referring to only employer and contractor. In most respects consultants exercise their normal skills which do not need further discussion. This chapter highlights special features of their relationships and dealings when acting in a design and build scheme. Apart from the distinction between designers and quantity surveyors, the most fundamental one is between consultants working for the contractor and those working for the employer, and in this contractual pattern they do work for one or the other. A lesser distinction is between consultants directly on the staff of the employer and contractor, that is 'in-house', and those engaged from outside on a contract basis, and so properly 'consultants'. All types of designers, for present purposes, are included.