For most works of any size there should be separate bills for obviously separate parts of the project. This clarifies the location of work under bill items, makes it possible to cost structures separately, and may be needed if completion of certain parts of the work is required by some stated earlier time. Within each bill the items will be classified into different types of work, always taken in the same order in all bills.
The standard method lists 26 classes of work labelled A–Z; Class Abeing for general items (more commonly known as ‘Preliminaries’); Class B is for site investigation including sampling and laboratory testing; Class C for geotechnical processes, such as grouting and construction of diaphragm walls; Class D for demolition and site clearance. Thereafter there follow classes for the common constructional operations – earthworks, concrete, pipework, etc. – through to Class Y which is for sewer and water main renovations. The final Class Z is for ‘Simple building works incidental to civil engineering works’ and covers carpentry and joinery, doors and windows, surface finishes and services, etc.
Not all the 24 classes of construction work, B–Y, will normally be used on most projects, and a problem is that if the project includes a large building, the items under Class Z may be numerous and so need sub-classification. There may also be some difficulty in deciding where to bill certain types of work to achieve a logical order, since some work which would normally be considered part of the finishing building trades, such as painting, is in the civil engineering classes of work.
For UK jobs the standard method of classification is normally used because there are computer programs available to aid billing which are based on the A–Z classification. For overseas work a non-CESMM method of billing is used, which allows the classes of work adopted to follow the logical building order.
Number of items. Some civil engineering bills of quantities contain upwards of a thousand items because many different types of operations over many different structures are involved. Where possible, an effort should be made to keep the number of items to no more than they need be. This helps to reduce the work involved in measurement throughout the contract; but departures from the standard method may make the estimator’s task more difficult and so should be kept to the minimum necessary.
The question of how detailed the billing should be depends on the nature and size of the works. What is to be measured for payment can vary widely.
For instance, in a contract for the construction of a dam, some minor gauge house might be billed as a single lump sum item; the drawings and specification providing all details of what is required. Often where there are repetitive structures, such as access chambers to valves on a pipeline, these too can be billed complete by number.
In civil engineering it is quite common to bill items, such as standard doors simply by number, the specification describing what is required including the frame, priming and painting, and the type of door furniture required. If a special door is required, such as for the front entrance, again this is shown on the drawings and specified in detail; so the item in the bill appears as ‘Front entrance door…1 No.…’.
Where methods of measurement depart from the ICE standard method, this must be made clear in the bill. Although the standard method permits the description of an individual item to make clear it is not measured according to the standard method, it is better to group such items together. Either they can be grouped under some appropriate sub-heading, or it may be decided that certain types of work throughout the bills are not to be measured according to the standard method. When this policy is adopted, a statement must appear in the preamble to the bills of quantities (see below) saying such as ‘Painting of metalwork is not measured separately and is to be included in the rate for supply and fixing of metalwork’. To prevent errors, a sub-heading before metalwork items should repeat this briefly, for example, ‘Following items including painting’.