The six checks
They address different defects and none replaces the others. The checks accumulate rather than substitute for one another.
The coverage check. Does every work described in the technical clauses find an item.
The reverse check. Does every item refer to an identifiable requirement.
The unit check. Does each item carry a unit suited to what drives its cost.
The rule check. Is the measurement rule stated or referred to, notably for items by area.
The geometric consistency check. Are the quantities compatible with each other and with the drawings.
The readability check. Would a third party understand each item without further explanation.
| Check | What it catches | Order |
|---|---|---|
| Geometric consistency | Quantities incompatible with the drawings | First |
| Completeness of items | Missing works | Second |
| Units and measurement rules | Unsuitable units | Third |
| Scope of items | Areas assigned to nobody | Fourth |
| Consistency of clauses | Contradictions between documents | Fifth |
| Overall read-through | Remaining ambiguities | Last |
The order in which to run them
It is not indifferent.
Start with coverage, since a missing work invalidates everything that follows.
Continue with the reverse check, which reveals orphan items, often inherited from an earlier project.
Then address unit and rule, which condition comparability.
Finish with geometric consistency and readability, which are quality rather than completeness checks.
Reversing this order wastes time, since you check the consistency of items that are about to disappear.
The geometric consistency check
This is the one that catches the costliest errors. It concerns consistency between items and quantities.
Some quantities are linked to each other by the geometry of the project. A floor area, a ceiling area and a skirting perimeter stand in verifiable relationships.
A discrepancy between linked quantities signals an error, either of measurement or of reading the project.
This check does not require recalculating the measurement, only verifying that the orders of magnitude hold together.
It catches data-entry errors in particular, which are frequent and invisible on a line-by-line reading.
What a check does not detect
Three limits to know.
A design error. If the project itself is inconsistent, the schedule will reflect it faithfully.
An unsuitable requirement. A correctly quantified work may be technically inappropriate.
A price assumption. The schedule carries no prices; checking it says nothing about the amount to expect.
These three limits justify distinguishing checking from estimating, covered from the budget angle in the guide on construction costs.
The output to produce
Three documents, more useful than a mere read-through. They record the check and serve in a dispute.
The list of corrections made, dated, documenting the work.
The list of points left open, with the decision awaited from the client.
The note of assumptions, setting out the measurement positions adopted where the project does not decide.
The third document is the most valuable in any later dispute, since it shows what was known and what was not at the time of tender.
What this means for a professional
Four rules.
Check before issue, a later correction requiring every contractor to be re-approached.
Run the six checks in order, coverage first.
Document the measurement assumptions, rather than keeping them in your head.
Distinguish corrections from queries, the former for the checker, the latter for the client.
This article sets out a method of professional orientation. It reproduces no content from normative documents.