Some problems of billing


Apart from excavation by dredging or for cuttings; the CESMM distinguishes only between excavation for foundations and general excavation (listed in that order). However, the more logical order should be adopted of billing general excavation to a stated level (the final surface for that item) followed by excavation for foundations below the final surface for the general excavation.
This can result in items referenced E400 in accordance with CESMM, preceding those referenced E300; but these references should not be changed.
If the general excavation has to be taken down to two different levels, that is to a stepped formation, then under the CESMM method it is billed as one item to the lower of the two final surface levels. If an attempt is made to bill it as two excavation items banded horizontally, one below the other, sundry complications occur which are best avoided as they can cause confusion. Nor should it be taken as two separate items, the depth of each being measured from ground surface, because it is not excavated in this manner when the areas are adjacent.
Rock excavation has to be itemized separately from other materials, the volume of rock being measured independently. Usually neither the quantity nor the depths at which rock will be encountered will be accurately known; but the quantity should be estimated on the basis of the geophysical data available.
The latter must be supplied to tenderers to permit them to make their own judgement as to the depth and extent of rock likely to be encountered.
The definition of rock presents difficulties, but it must be stated in the preamble to the bills of quantities. Geophysical data may occasionally permit a given rock to be defined, but in most cases rock is probably best defined according to the method of excavation. Unfortunately methods for removal can vary greatly, but for specification purposes three methods can be distinguished:
use of explosives;
use of hydraulic hammers or compressed air-operated tools;
use of mechanical rippers (in open excavations).
It is usual to combine the first two methods to define rock by defining them as Rock is material requiring to be loosened or broken up in situ by use of  explosives or hydraulically operated rock hammers or compressed air-operated rock breaking equipment before being removed. From the contractors point of view this is not entirely satisfactory since it would exclude payment for rock he can get out with a suitably powerful digger able to cope with hard bands, albeit with difficulty and at a slow rate, involving substantial extra cost. Hence mechanical ripping forms a third category which may warrant separate measurement where hard bands of material are encountered that cannot be broken up by scrapers or the normal bucket excavator, but do not qualify as rock.

Measurement of rock excavated for valuation is not easy; it is best done by a member of the resident engineers staff and the contractors staff viewing the excavation together in order to agree on the rock volume.

Working space

Contractors often claim payment for additional excavation to provide working space, despite the fact that most contracts and methods of measurement clearly state that only the volume vertically above the limits of foundations will be measured for payment. Therefore if some exterior tanking or rendering to a basement is required, it is advisable to repeat in the item for this that the contractor must allow in his rates for any working space he requires.


Trench excavation for pipelines is covered piecemeal in Classes I, K and L of the standard method (Class J covers provision of fittings and valves). Trench excavation to pipe invert level is included in the supply, laying and jointing of pipes per linear metre in Class I. Excavation below that for bedding is included in the supply and placing of bedding material, also per linear metre, in Class L. Extra excavation for manholes is included in the rates for manhole construction in Class K. Rock is an extra item payable per cubic metre in Class L. All pipework excavation items include backfilling.
Excavation of joint holes is not specifically mentioned so needs to be specified as included in the rates.
If the standard method of measurement is not used, it can prove simpler to take excavation (including backfilling) separately from pipe supply and laying.
The maximum and average depth of trench, including any depth required for bedding, is stated for any given length of pipeline and is taken for payment per linear metre. Excavation for joint holes should be stated as not measured but included in the rate for trench excavation. The drawings should show the standard trench widths taken for payment, and the depth of any bedding. Rock is paid for as an extra over per cubic metre within the payment limits, the rate to include for overbreak and backfilling thereof. Bedding, haunching and surrounding are measured per linear metre for supply and placing.

Thrust blocks for pipelines have to be constructed against vertically cut undisturbed ground. It avoids argument if items for thrust blocks to dimensions shown on the drawings are followed by an extra-over item for trimming sides of excavation adjacent to thrust blocks to the vertical, including any backfilling between a thrust block and the vertical excavated face with concrete.
Under the CESMM thrust blocks are measured per cubic metre inclusive of concrete, formwork, reinforcement, etc. For large pipes requiring major blocks it may be better to deviate from the standard method by treating these blocks as structures in their own right.

Earthwork construction

Earthwork construction is measured as the net volume as placed. The source of the filling should be stated. All information available about the nature of the proposed fill material should be supplied to tenderers so they can make their own estimate of the bulking factor of loose filling, its weight per unit volume loose and when compacted, etc. When the filling is to be obtained from a borrow pit, information concerning the extent and characteristics of the borrow pit material and its location should be provided in the tender documents.
If specified material for filling is to be obtained from selected material from a borrow pit, the removal or set aside of unsuitable material from the borrow pit has to be included in the rate for filling. It may also be necessary to include re-handling of the unsuitable material in order to put it back into the borrow pit.
It is impracticable to measure the unsuitable material because some may be worked around and left in situ. Hence it is important to define what the rates for placing filling obtained from a borrow pit are to cover. Failure to include any necessary double-handling of unsuitable material can result in a large claim for extra payment from the contractor. It is advisable to give separate items for stripping overburden from the borrow pit, and an item for reinstatement of the borrow pit. The specification should set out all the requirements needed for reinstatement which it should then be possible to bill as a lump sum item for pricing. One point to note is that when suitable material has to be taken from a borrow pit, it may be helpful to specify instances of unsuitable material also.


Concrete in situ is measured in the CESMM as two operations: (i) supply according to various quality grades; and (ii) the placing of concrete according to its location in beams, columns, slabs, etc. This suits the modern practice in the UK and similar developed countries where widespread use is made of ready-mix concrete delivered to site. The totals of concrete in the various grades must therefore sum the same as the relevant placing items per grade.

If the CESMM is not used, the supply and placing of concrete can be itemized together, the grade of concrete being stated. This reduces the number of items in the bill and simplifies measurement for valuation.
If holes in flat slabs have to be left open for some other contractor, such as a separate plant contractor, then the bill should include items for the supply and fixing of temporary covers to them to prevent accidents.


The standard method (CESMM) measures brickwork per m2, the thickness being stated. It does not classify brickwork according to height above ground, nor separate out cavity walling in brickwork. It is therefore simpler to adopt non-CESMM billing, that is, measuring external brick walling from footings to d.p.c. level; and thereafter in one- or two-storey heights; separating cavity wall brickwork (including provision of wall ties) from solid brickwork; and either including provision of facing bricks and fair-face jointing in the cavity walling, or allowing this as an extra over. The specification must set out in detail what is required in respect of type of bricks and blocks to be used, and wall ties, surface finish and type of joint, etc. The bill item descriptions should also repeat what is to be included in the price quoted. Where ventilators to walls are required, these can be itemized inclusive of building in. Masonry or precast concrete cladding needs to be billed separately, and angle supports, cramps and dowels (often of stainless steel) should be included or itemized separately.
Other items separately billed will be d.p.cs, lintols, brick arches, etc.

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