The regulatory definition
Belgian public procurement rules define the summary bill of quantities as the document, specific to works contracts, that divides the works into distinct items and states, for each, the quantity or the manner in which its price is to be determined. The definition is regulatory rather than customary.
Three elements deserve noting in that definition. They concern the nature of the document, its object and its scope.
Division is the primary function. The bill breaks the works into elemental units. That division is not neutral: it determines what contractors will price.
The quantity is not always given. The definition allows for a method of determination instead, which opens the way to items whose price is calculated otherwise than by multiplying a rate by a fixed quantity.
The document belongs to the contract. It is not an internal working paper but a contractual element, binding on the parties.
What the bill actually serves
Four functions combine, and they concern different parties. The bill serves in turn to price, compare, execute and settle.
Making tenders comparable. That is the central function. All contractors price the same list, in the same order, with the same quantities. Without it, comparison would bear on different scopes.
Serving as the basis for payment. Interim valuations rest on the items of the bill and on quantities actually executed, covered in the article on variations and interim valuations.
Serving as the basis for changes. Work added during construction attaches to the bill, and its price is discussed from the rates it contains.
Documenting the scope. The bill states what is included in the contract. What does not appear in it is, in principle, not due.
What the bill is not
Three common confusions deserve clearing. They concern the bill, the quotation and the specification.
The bill is not an estimate. An estimate assesses a probable cost. A bill describes a scope and quantities. One can prepare a bill without knowing a single price.
The bill is not the specification. The specification describes the works and sets the requirements. The bill divides and quantifies them. The two documents must correspond, which is the subject of the article on matching specification and measurement.
The summary bill is not the detailed measurement. The first is the contract document, the second is the calculation that produced the quantities. That distinction is covered in the article on summary and detailed measurement.
| Function of the bill | For whom | At what stage |
|---|---|---|
| Pricing | Tenderer | Tender submission |
| Comparing | Contracting authority | Analysis of tenders |
| Executing | Contractor and supervision | During the works |
| Settling | Both parties | Final account |
Who prepares and who checks
The division of roles is a source of frequent misunderstanding. It is fixed by contract rather than by custom.
The designer prepares the bill as part of their appointment, consistently with the particular specification they draft.
The tenderer checks it. This is not optional: Belgian public procurement rules require the tenderer to report errors discovered, under conditions covered in the article on who bears the risk of a quantity error.
The client bears the economic consequences. An incomplete bill translates into additional works, with an unfavourable balance of power since competition no longer applies.
Why the quality of the bill governs everything
A poor bill cannot be repaired later, and three effects compound. They touch comparability of tenders, execution and the final account.
Comparison of tenders becomes misleading. If an item is missing, contractors interpret it differently: some absorb it elsewhere, others omit it. The price gap then no longer measures competitiveness.
The balance of power shifts during construction. Omitted work will be carried out, but at a price negotiated without competition.
Cost control becomes difficult. Without a reliable basis for comparison, distinguishing an overrun from a change of brief requires reconstruction work.
The articles in this branch
The article on item, quantity and unit describes the structure of a line. The measurement conventions are set out there.
The article on provisional and lump-sum quantities covers the allocation of quantity risk. The allocation of risk is explained there regime by regime.
The article on summary and detailed measurement distinguishes the two documents and their functions. The distinction between the two documents is drawn there.
This article reflects rules and professional practice at the date of checking and serves as orientation. It does not constitute legal advice and does not replace assessment of the individual case.