Ordering criteria side by side
The standard expressly provides for costs to be ordered by further criteria. These criteria sit alongside the cost groups rather than replacing them.
| Ordering criterion | What it is needed for |
|---|---|
| Cost groups by element | comparability with benchmarks, cost control across stages |
| Procurement packages and trades | tendering, award, accounting |
| Execution types | comparing options, material decisions |
| Construction phases and sections | control where delivery is phased |
| Types of measure in existing buildings | showing strip-out, disposal, repair and new work separately |
The last row is particularly useful in existing buildings. Since partial demolition and repair are allocated under the standard to the cost group whose element they affect, they spread across the whole of cost group 300. An additional ordering criterion makes them visible again as a block without abandoning the element structure.
What happens when the leading ordering changes
From the pre-tender estimate onwards the standard additionally orders by procurement package, and the tender sum follows that ordering. The change is substantively unavoidable, because what is procured is what a contractor executes.
It has two consequences, both of which argue against a complete switch. Both concern tasks that still have to be performed after procurement.
| Consequence | Why it arises |
|---|---|
| Cost control breaks off | trades and element groups are not congruent; case law has held that schedules by trade and updates by cost group yield no comparability beyond the bare total |
| Chargeable costs become harder to derive | chargeability attaches to cost groups; a purely trade-based schedule does not permit determination without an allocation |
The workable answer is to retain the cost group structure as leading and carry procurement packages in parallel. The system is covered in the article on trade-oriented cost structure.
Why the standard permits the switch nonetheless
The standard expressly allows a cost determination to be structured on an execution basis, that is by trade or procurement package rather than by element. This is no contradiction but a response to particular project situations.
Modernisation is named in particular. In existing buildings the element structure is frequently less informative than the trade structure, because whole elements are not created; individual measures are carried out on existing ones.
Trade-oriented structuring is permissible so long as chargeable costs can still be properly determined from it. That qualification is the real condition and belongs in the agreement.
Model-based methods
Where design proceeds with a building information model, what changes is not the structure but the origin of the quantities. Model elements are linked to cost groups, quantities are taken across and priced with benchmarks or unit rates.
The benefit lies less in speed than in traceability: every quantity remains attributable to a model element, and a design change acts directly on the cost determination. Cost determination thus becomes an analysis of the model rather than a schedule of its own.
The limits lie in the level of detail of the model, which varies considerably between design phases and between disciplines. The system and its preconditions are covered in the article on BIM-based cost determination.
Reference units as the silent precondition
Every cost group has a reference unit in which quantities are measured. It is the precondition for an item being comparable at all, and it is the thing most frequently omitted in practice.
The difference shows when two projects are compared, and it decides whether the comparison explains anything at all. Without the reference unit any comparison is a ranking without an explanation.
| Figure | What it permits |
|---|---|
| amount per cost group | establishing that one is more expensive |
| amount per reference unit, e.g. per m² external wall, per m² roof, per m³ excavation | establishing why |
A recommendation follows for cost determination that costs little and achieves much: alongside the amount per cost group, carry the corresponding quantity. Only then does a later deviation reveal whether quantity or unit rate was the cause, and that is exactly the distinction cost control requires.
What makes the difference in practice
Four requirements follow from the foregoing, applying regardless of project size and tools. None of them presupposes any particular software.
| # | Requirement | Why |
|---|---|---|
| 1 | Fix a leading ordering | keep it across all stages, normally the cost group structure |
| 2 | Carry additional ordering criteria in parallel | switching instead of adding loses comparability |
| 3 | Show quantities and unit rates separately | so that variances stay attributable |
| 4 | Record the allocation rules | a decision that exists only in the preparer's head survives neither a change of staff nor an audit |
What the standard does not cover
DIN 276 captures the costs of the construction project, that is the investment. Costs arising after handover are the subject of a separate standard.
The separation is clean but creates a gap in the basis for decisions, because many design decisions shift costs between investment and operation. How the relevant standards relate to one another is covered in DIN 276, DIN 277 and DIN 18960 compared.
This article reflects the position at the date of checking and serves professional orientation. It does not constitute legal advice and does not replace assessment of the individual case.