These apply where ICE or FIDIC (or similar) measurement contracts are used, incorporating a bill of quantities for pricing, as described in Chapter 1
Section 1.2. Where additional work is required, the contractor is paid for it at ‘bill rates’ or, if different work is required, this is paid at similar or agreed rates. Table 3.1 compares this method with the methods which follow.
The advantages are that the contractor can be paid fairly for the amount of work he has to do, and the employer only has to pay for work actually required, without having to pay a premium to the contractor for the risk of undertaking, at his own cost, extra work due to quantity changes. Thus if no major unforeseen conditions are encountered and the employer orders no extra work, the cost of the job to the employer will come very near the original
The use of bills of quantities has been the normal method of payment in standard forms of contract for many years. This method is particularly effective where the employer wishes to control the design, or has the works largely designed before going out to tender. With the works clearly defined, and a fair system of measurement, the contractor’s risks are reduced and pricing may be keen.