Variations - Building Contract Claims - page 316

in one particular. There seems to be no provision for the employer or the
quantity surveyor on his behalf to negotiate on the quoted price. It is either
to be accepted or rejected.
Approximate quantities, defined and undefined provisional sums
The concepts of defined and undefined provisional sums and approximate
quantities were introduced into, what was then, JCT 80, in July 1988. Briefly,
the situation is this 595 . Where work can be described in items in accordance
with SMM7, but accurate quantities cannot be given, an estimate, called
'approximate quantity' must be given. If the work cannot even be described
in accordance with SMM7, it must be listed as a provisional sum. Provi-
sional sums are either defined or undefined. If 'defined', the bills must state
the nature and construction, how and where the work is fixed to the
building and any other work fixed to it, quantities giving an indication of
the scope and extent of the work and any specific limitations. If any of this
information cannot be given, the work is 'undefined'.
Provisional sums for defined work are deemed to have been taken into
account in the contractor's programming and pricing preliminaries. There
will be no adjustment unless measured work in the same circumstances
would be adjusted. If the work is undefined, the contractor is deemed not to
have made any allowance for it in programming and pricing preliminaries.
This addresses a difficulty which contractors have and which is often
misunderstood. The fact is that a contractor will be unable to make any
sensible attempt to programme or price preliminaries to deal with a provi-
sional sum which may be little more than a title and a figure. For example,
'mechanical installation ¼ £10,000' is almost meaningless. It used to be
common, however, for architects to demand that the contractor made
some allowance in his programme for provisional sums of this kind. Setting
aside the difficulty of complying with such a request, the request itself
demonstrates a lack of understanding that the 'bar' on the bar chart is, or
should be, simply the result of a series of complicated calculations taking
into account the way in which the work will be integrated into other work
and the way in which it will be priced. Rules 10.1 to 10.6 usefully set out the
minimum information which the contractor must know before he can plan
and price the effects of the item in question.
The valuation of work for which an approximate quantity is included in the
contract bills is covered by clauses 13.5.1.4 and 13.5.1.5. Where the approxi-
mate quantity is a reasonably accurate forecast, the valuation must be in
accordance with the rates for the approximate quantity. If it is not a reason-
ably accurate forecast, the rates form the basis for the valuation, but the
quantity surveyor is to make a fair allowance for the difference in quantity.
No allowance for either addition to or reduction of preliminaries can be
made under clauses 13.5.1 or 13.5.2 if the valuation relates to an architect's
instruction to expend a provisional sum for defined work.
595 A full description is to be found in General Rules 10.1 to 10.6 of SMM7.