Measurement & tickets
Take-off to REB 23.003: basics, formulas and digital capture
What REB 23.003 governs, why the calculation matters more than the result, and how take-off data is exchanged via DA11 and X31.
What does REB 23.003 govern?
REB 23.003 is the German rule for formula-based quantity determination in construction. It sets out which formulas quantities are calculated with from take-off data – and in what form that calculation is documented.
Its practical core is not the mathematics. It is traceability: on a public contract a quantity is not a number but a claim that has to be evidenced. REB prescribes what that evidence looks like.
Why the calculation matters more than the result
Anyone who can only produce the final total at an audit ends up in a discussion. Anyone who can show the formula with its input values is finished.
An example: an area of 128.50 m² can come from a rectangle, from several part-areas with deductions, or from a station take-off. The result is identical, the evidential value is not. The auditor wants to see how you arrived at the figure – particularly where recesses were deducted.
Which is why the decisive question to put to any software is not “does it calculate REB?” but “does the calculation stay attached to the item?”.
The common formulas
REB 23.003 contains a whole series of formulas. In road construction and Tiefbau you mainly meet these in daily work:
| Application | What for |
|---|---|
| Rectangular and triangular areas | patches, part-areas, simple break-ups |
| Areas with deductions | paved areas with recesses, manholes, tree pits |
| Station take-off | carriageways, trenches – area and volume across stations |
| Body calculations | excavation, backfill, frost protection layer |
The station take-off is the most important form in civil engineering: widths or cross-sections are recorded at regular intervals (stations) along an axis, and area and volume follow from them. For a trench or a carriageway that is the natural way to measure.
A worked example
Take a carriageway area recorded at three stations:
| Station | Width |
|---|---|
| 0+000 | 3.10 m |
| 0+020 | 3.40 m |
| 0+040 | 3.20 m |
Between two stations the area is formed from the mean width and the spacing:
- Section 1: (3.10 + 3.40) ÷ 2 × 20 = 65.00 m²
- Section 2: (3.40 + 3.20) ÷ 2 × 20 = 66.00 m²
- Total: 131.00 m²
These three lines are precisely the evidence. They stand like this – with stations, widths and subtotals – on the take-off sheet, and they have to do so in the system too.
From sheet to system: DA11 and X31
Take-off data is exchanged between programs through two formats:
| Format | Purpose |
|---|---|
| DA11 | take-off data in the classic GAEB data exchange |
| X31 | the same job in the XML version |
It becomes relevant as soon as a design office, a surveyor or the client processes the data further. Anyone calculating purely internally manages without – anyone doing Straßenbau for public clients tends not to.
The step everybody underestimates: the input
Every take-off program calculates reliably once someone has entered the values. That is exactly where the effort sits: a crew leader measures on the road and writes on paper; in the office somebody types the same figures a second time.
That second pass is not only time, it is also the most common source of error. A transposed digit while typing is invisible – the formula calculates with it without complaint.
How to avoid the typing without giving up the paper is described in Digitising handwritten site sheets .
What makes a good take-off sheet
Independently of any software:
- List stations or part-areas individually, not just the total.
- Name the deductions, do not merely deduct them – “less manhole 1.20 × 1.20”.
- Date and signature, because the sheet is the evidence.
- Item number from the contract, not your internal one.
- One sheet per call-off or construction section, so the assignment stays unambiguous.
These five points decide more about a smooth audit than the choice of program does.
Frequently asked
Do I have to know the formulas by heart? No. You have to be able to recognise whether the formula applied fits the situation – and for that it has to be visible.
What if we calculate differently from the program? Then you correct it. A calculation you cannot change is not a calculation, it is a result.
Does REB apply to very small quantities too? For a patch of three square metres the simple area is as a rule enough. Formula-based determination becomes mandatory where the contract provides for it – a look at the contract conditions is worth it.
Where do I find the rule in full? The REB procedural descriptions are issued through the responsible federal and state bodies. For daily work the implementation in the program is usually enough – for a dispute the wording should be to hand.
Second example: excavation across stations
Areas are the easy case. In Tiefbau it is mostly about volume, and there the benefit of the station take-off shows more clearly.
A pipe trench recorded at four stations. Width and depth are written down:
| Station | Width | Depth | Cross-section |
|---|---|---|---|
| 0+000 | 0.80 m | 1.40 m | 1.12 m² |
| 0+015 | 0.80 m | 1.60 m | 1.28 m² |
| 0+030 | 0.80 m | 1.75 m | 1.40 m² |
| 0+045 | 0.80 m | 1.55 m | 1.24 m² |
Between two stations the mean of the two cross-sections is formed and multiplied by the spacing:
- Section 1: (1.12 + 1.28) ÷ 2 × 15 = 18.00 m³
- Section 2: (1.28 + 1.40) ÷ 2 × 15 = 20.10 m³
- Section 3: (1.40 + 1.24) ÷ 2 × 15 = 19.80 m³
- Total: 57.90 m³
The value of this breakdown lies not in the result but in the fact that every intermediate line is checkable. If a depth is questioned, that concerns one section – not the whole quantity.
Anatomy of a take-off sheet fit for checking
Whether you work on paper or digitally, the same entries belong on the sheet:
| Area | Content | Why |
|---|---|---|
| Header | client, contract, call-off, date | Without assignment the quantity is worthless |
| Header | item number from the contract bill of quantities | The language of the audit |
| Lines | stations or part-areas individually | Checkability per section |
| Lines | deductions named, not merely deducted | “less manhole 1.20 × 1.20” |
| Footer | subtotals and final quantity | Traceability of the addition |
| Footer | name and signature | The evidential character |
The most common shortcoming is the fourth point. A deduction without a description looks like an arithmetic error at the audit, and clearing it up costs more time than the description would have.
DA11 and X31 in practice
The data exchange sounds more technical than it is. Two situations where it is genuinely needed:
A design office has surveyed. The take-off data arrives as a DA11 or X31 file and has to go into your billing. Without an interface you retype the stations – with everything that means in terms of errors.
The client demands the take-off data. Some authorities want not only the invoice but the take-off file, so they can recalculate it in their own system. Then the format is not a convenience but a precondition.
If neither case occurs with you, you do not need the interface – and should not pay for it either. If in doubt, ask your largest client before you select on that basis.
Common calculation errors
| Error | How it arises | How it is noticed |
|---|---|---|
| Part-area captured twice | two sheets for the same section | quantity exceeds the area on the ground |
| Forgotten deduction | manhole or tree pit overlooked | auditor measures it again |
| Wrong unit | m² instead of m³ for excavation | the amount is out by orders of magnitude |
| Stations mixed up | recorded in the wrong order | implausible progression of the cross-sections |
| Transposed digit while typing | second capture in the office | as a rule not noticed at all |
The last one is the most expensive, precisely because it stays invisible. A transposition downwards is never objected to by the client.
Joint take-off with the client
The VOB knows the joint take-off: client and contractor establish the quantities together. Where it is agreed, you should insist on it – it is the most effective protection against later discussions.
What a joint take-off means in practice:
| Step | Who | Result |
|---|---|---|
| Arrange the appointment | you | in good time before the work is covered up |
| Measure together | both | each side with its own notes |
| Sign the sheet | both | quantity established by agreement |
| Note discrepancies | both | name the disputed points instead of glossing over them |
The second point is why this belongs here: work that will no longer be visible later has to be measured before it is covered. A backfilled trench cannot be re-measured. Anyone who misses the appointment depends on their own Zettel – and on the client accepting it.
If no joint take-off comes about, the rule is: measure, document, photograph, send the result. A take-off that has gone unchallenged is worth considerably more than a figure that first appears with the invoice.
In summary
REB 23.003 is less a calculation rule than an evidence rule. The formulas are craft; the value lies in the calculation being open to inspection. Anyone capturing take-off digitally should therefore first check whether the calculation is preserved – and only afterwards how fast the input is.
How Levora implements that is on the page about take-off to REB 23.003 . Which file from the tender supplies the items is settled in the article GAEB X81, X83, X84, X89 .
Calculate on your own take-off sheet
Bring a sheet where the check has snagged once before. Whether the calculation holds shows up fastest on that.
Request a demo