The precondition
A bill of quantities presupposes that the scheme is fully designed and that an unambiguous schedule of quantities exists. Where that condition is absent, the problem is not the bill but the timing of the tender.
That precondition is stricter than it sounds. It means detailed design must be advanced far enough for every item to be described and its quantity measured. Where that is not so, provisional items, daywork and gaps arise, that is precisely the elements the VOB/A restricts.
The link to design is therefore direct: a bill of quantities cannot be better than the detailed design it rests on. The relevant work phase is covered in the article on work phases 4 and 5.
The structure
A bill of quantities is hierarchical. The depth depends on project size; the principle does not.
| Level | Content |
|---|---|
| Preliminaries | general particulars about the project and execution |
| Lot or procurement package | the unit being procured |
| Section | division by element or construction phase |
| Item | the individually priced work |
Every item carries an Ordnungszahl, a unique reference number. It stays unchanged throughout the project and serves as the reference in tender, order, measurement and final account.
The item number is no formality. Changing it during the project breaks the links between tender and account, and the verifiability of the invoice suffers. Supplementary items therefore receive new numbers rather than existing ones being renumbered.
Structuring by procurement package also acts on cost planning, since from the pre-tender estimate onwards it governs the ordering of cost determination. The system is covered in the article on trade-oriented cost structure.
What belongs in the preliminaries
The preliminaries contain what applies to several or all items and should therefore not be repeated in each. Four contents belong there in every case.
| Content | What belongs there |
|---|---|
| Particulars about the site | condition of the ground, access routes and their restrictions, existing installations, storage areas; section 0 of the relevant ATV lists what must be stated |
| The equivalence clause | where technical specifications are referred to, equivalent ones count as admitted even without an express addition; its absence is a procurement defect |
| The applicable edition of the standards | which edition of the VOB/C applies, because the ATV are revised at multi-year intervals |
| Divergent measurement rules | where section 5 rules are to be departed from, for instance for model-based measurement, it must be agreed here |
A note on the limit: preliminaries may supplement items but not replace them. Material characteristics determining the price of an item belong in the item, not in a general preamble.
How an item is built
An item has three components, each with its own function. Only one of them is the governing contract text.
| Component | Content | Function |
|---|---|---|
| The short text | names the work in one line | orientation; it appears in price comparisons and analyses |
| The long text | type, execution, material, dimensions, requirements, conditions of execution | the governing contract text |
| The quantity with its unit | how much is measured and in what unit | the unit must correspond to the measurement rule of the relevant ATV |
The third line contains the commonest error. The unit of measurement follows the ATV, not convenience. Tendering a wall by square metre where the ATV provides for volume creates an item whose measurement becomes contentious. The system is covered in the article on reading the ATV.
What does not belong in the long text
Three contents are regularly included in item texts and do not belong there. All three lengthen the text without improving the scope of work.
| Content | Why it does not belong in the item text |
|---|---|
| Incidental services under the VOB/C | they are owed in any event; repeating them lengthens the text and suggests that other incidental services are not owed |
| Product names without an equivalence reservation | they restrict competition and are open to challenge under procurement law |
| Risk transfers | they breach the prohibition on unusual risk and either produce risk premiums or are ineffective |
Item types and their limits
Alongside normal items, practice knows further types, and the VOB/A expressly restricts two of them. Both concern work whose extent is open at tender.
| Type | Permissibility |
|---|---|
| Normal item | default |
| Alternative item | permissible where a genuine choice exists |
| Supplementary item | permissible, adds to a base item |
| Provisional item | as a rule not to be included |
| Attached daywork | only to the extent strictly necessary |
The last two rows share one rationale. Both move price formation out of competition and into construction, impairing comparability.
A checking question follows for every provisional item: why is execution open. Where the answer is that design is incomplete, the problem lies not in the bill of quantities but in the design.
Data exchange
Bills of quantities are exchanged in structured form between programs. A standardised procedure defines phases covering the route from preparation through tendering to final account.
The benefit lies in avoiding re-entry and in automated tender checking. It presupposes that the structure of the bill meets the requirements of the exchange format, particularly on item numbering. The article on GAEB data exchange covers the phases.
Related articles
This article reflects the position of the standards at the date of checking and serves professional orientation. It does not constitute legal advice and does not replace assessment of the individual case.