The document does more work than any other
The employer’s requirements are the only description of the building you are buying. Everything else in a design and build contract is machinery: how payment runs, how time is extended, how disputes are handled. The requirements are the subject matter, and once the contract is executed they are extremely difficult to improve.
That imbalance is not reflected in how the document is usually produced. It is often assembled late, from consultant reports written for a different purpose, and reviewed for completeness rather than for how it will be priced.
They are also the document a funder will read when testing whether the scheme is deliverable at the price, and the document an adjudicator will read first if the parties end up in front of one. It is worth writing for both of those readers as well as for the contractor.
How a contractor reads it
A contractor’s estimator reads the requirements looking for the cheapest compliant answer, and they are entitled to. Where a clause says the finish shall be of high quality, that is not a specification, it is a range, and the price will sit at the bottom of it. Where a clause says the system shall achieve a stated performance measured by a stated method, there is nothing to interpret.
The test to apply to every clause is simple. If two competent contractors could satisfy this wording at materially different cost, the wording is doing nothing. Reading the document that way, before it is issued, is the single highest value hour on the whole appointment.
Four patterns that cost money
The first is aspiration without measurement: quality, robust, appropriate, to the satisfaction of. None of these can be enforced without an argument.
The second is a reference to a drawing that is marked indicative. Indicative drawings are useful and they carry no obligation, so a requirement that relies on one has no content.
The third is a performance requirement with no stated test method. Two parties can both be right about whether it has been met.
The fourth is silence. Anything the requirements do not mention is a matter for the contractor’s proposals, and if the proposals are silent too, it is a variation later.
Requirements and proposals have to be reconciled
The contractor answers your requirements with their proposals, and those two documents will not agree. Some divergences are improvements, some are reductions, and some are neither party noticing. The contract sets out which document takes precedence where they conflict, and the answer varies with the edition in use and with any amendments made to it. [VERIFY: the precedence provision in the JCT design and build edition and amendment set in use.]
What does not vary is the value of doing the reconciliation before signature, document by document, with each divergence recorded as accepted, corrected or priced. It takes days to produce and years to reconstruct.
What a testable requirement looks like
The difference is easiest to see side by side. A clause requiring windows of high acoustic performance is a range, and it will be priced at the bottom of it. A clause requiring a stated acoustic performance measured by a stated method, verified by testing on a stated proportion of installed units, is a specification. Both are one sentence. Only one of them can be enforced.
The same applies to workmanship, where the usual failure is a reference to good industry practice. Practice is not a standard and it is not a document. Naming the standard, and naming what happens when it is not met, converts an argument into an inspection.
It applies most expensively to interfaces. Where two systems meet, the requirements should say which party is responsible for the junction and what the completed junction has to achieve. Design and build transfers design risk, but only for what the requirements described. An interface nobody described is an interface nobody priced.
None of this requires a longer document. It usually produces a shorter one, because a testable clause replaces three aspirational ones and removes the need for the correspondence that used to follow.
What this means for you
Get the requirements reviewed by somebody whose job is to price them adversarially, before they are issued rather than after the tenders return. That review is cheap relative to a single specification argument on site.
If you are already past signature, the reconciliation is still worth doing, because knowing where the divergences are is what turns a later argument into a negotiation. We do that work as part of the employer’s agent appointment.
Where the requirements are already issued and you suspect they are loose, the exercise still has value before tenders return. Clarifications issued during the tender period are considerably cheaper than variations issued after signature, and a tenderer will usually welcome a document that removes ambiguity, because ambiguity carries risk they have to price.