Potential heads of claim - Building Contract Claims - page 93

costs should be ascertained, because the true costs resulting from a delay
will usually follow the delay itself. The few weeks at the beginning and end
of a contract will be characterised by a build-up then a reduction respect-
ively of site-related costs.
Therefore, if a contract is prolonged for a period of 6 weeks, which the
contractor can establish is a direct result of some clause 26 matters, the
6 weeks may be made up of several delaying occurrences taking place at
differing times during the contract period. The task of identifying each
delay and its monetary consequences is not always easy, but it must at
least be attempted. Many architects will agree to take a representative slice
of the appropriate number of weeks prolongation from somewhere in the
middle of the contract period. This seems, at first sight, to be a reasonably
good empirical method of establishing appropriate costs, but it is not an
ascertainment in the proper sense and it is difficult to substantiate if chal-
lenged. In practice, if both employer advised by the architect and quantity
surveyor and the contractor find that or some other approximate system is
acceptable, there is nothing more to be said.
6.2.2 Disruption
Disruption is usually claimed separately from prolongation. It may be
present with or without prolongation. Disruption has always been very
difficult to establish with any precision and even more difficult to ascertain
in monetary terms. Traditionally, a contractor's claim for disruption has
relied both for substantiation of the fact of disruption and the ascertainment
of its costs on the comparison of anticipated against actual labour costs. This
bald approach does not bear consideration and it has been roundly con-
demned 282 . There may be many reasons for the actual costs of labour being
greater than the contractor anticipated other than reasons for which the
employer or the architect are responsible.
Commonly, disruption amounts to delays in non-critical parts of a project,
but not to the extent that those parts become critical in programming terms.
For example, the task of fitting external balcony railings on the front of a
hotel project may not be critical. The contractor may have anticipated and
priced for it to take 3 weeks during a 5-week available time slot. Therefore, if
the work is delayed by one of the clause 26 matters so that it takes 4 instead
of 3 weeks, there will be no resultant prolongation of the contract period, but
the contractor will no doubt incur additional costs. That is a relatively
simple example and, provided the contractor has kept proper records,
there should be little difficulty in identifying the costs involved. Other
instances are more complex.
The classic method of evaluating disruption is to compare the value to the
contractor of the work done per man during a period of no disruption with
the value per man doing the disrupted period and then to apply the ratio to
282 London Borough of Merton v. Stanley Hugh Leach Ltd (1985) 32 BLR 51.