Variations - Building Contract Claims - page 317

Under clause 13.5.5, if the contractor's compliance with an architect's
instruction to expend a provisional sum
. for undefined work; or
. for defined work to the extent the instruction is different from the descrip-
tion in the contract bills; or
. the execution of work for which an inaccurate approximate quantity is in
the contract bills
substantially changes the conditions under which other work is carried out,
the other work is to be treated as though it was the subject of an architect's
instruction. This clause simply brings this kind of item under the same rules
as variations to measured work. The differences simply highlight the extent
of the contractor's knowledge about the kind of work and the amount at the
time the contract was made.
Performance specified work
Performance specified work is dealt with under clause 42. It was introduced
by JCT Amendment 12 in July 1993. Because, by specifying performance ,it
covers the design and installation or construction of work, the valuation
provisions in respect of this work differ from other traditional work. Clause
13.5.6 deals with the position.
The valuation of performance specified work must include addition or
omission of the work involved in preparation of drawings and other docu-
ments. It seems that the quantity surveyor has discretion to value the design
element alone in instances where the work itself is not carried out. Vari-
ations to the work are to be valued by using rates consistent with rates in the
contract bills for work of a similar character after making allowance for
changes in the conditions or the quantity in the bills or in the Contractor's
Statement. In the absence of similar rates, the quantity surveyor must make
a fair valuation.
Work omitted is valued in accordance with the rates in the contract bills
or in the analysis. Addition to or deduction from preliminaries must be
taken into account in the valuation. If daywork is the basis of the valuation,
the normal daywork clauses 13.5.4.1 and 13.5.4.2 will apply.
Clause 13.5.6.6 provides that if variations to performance specified work
or compliance with instructions to carry out such work, to the extent that it
differs from information provided in the contract bills, substantially
changes the conditions under which other work is carried out, the other
work is to be treated as though it was the subject of an architect's instruction
requiring a variation.
There is nothing of particular significance here and it is a fairly
standard treatment in line with the valuation of measured work and
provisional sum work noted above. Although the quantity surveyor must
exercise his duties within the parameters set down, he is given considerable
scope.