specter displays numerous dimensions per component - but which of these are suitable for AV work steps? This article provides an overview of useful assignments and explains how error messages in AV can be avoided and understood.

In this article we will show you:

Which dimensions are suitable for structural and finishing work
Examples of walls, floor slabs, beams, and ceilings
Typical sources of error in assignment
Meaning of AV error messages
Practical recommendations for improving data quality

1. Which dimension for which work step?

In structural work:
The dimensions for the component are entered in the AV. [Einführungsvideo]

Example 1: Wall formwork

Recommended dimension: Gross side area × 2 or outer surface area
Why: Openings (windows, doors) should be included or deducted. End formwork can be included optionally. Create wall-dependent tasks separately if necessary.
Note: Openings that are not explicitly modeled or floor-to-ceiling windows can lead to incorrect areas—check in CAD.

Example 2: Volume of a wall / floor slab / beam / blinding layer

Recommended dimension: Net volume
Why: The actual volume to be concreted is recorded correctly. Openings are deducted. No VOB-compliant billing.

Example 3: Volume of a non-modeled blinding layer

Recommended dimension: Base area × height of the SKS
Why: Volume is calculated using base area × height.
Note: Select result in m³, target size ME = m³.

Example 4: Reinforcing a slab

Recommended Dimension: Volume × Reinforcement Ratio Factor
Reason: The reinforcement ratio indicates the steel weight (kg) per cubic meter of concrete.
Typical reference values (kg/m³):

Component	Typical reinforcement ratio(kg/m³)	Usual range (kg/m³)
Floor slab	85	65 – 105
Foundation (footing)	85	70 – 100
Wall	100	80 – 120
Ceiling	95	80 – 110
Beam	130	100 – 160
Column	140	120 – 160

The tabular data corresponds to the standard values commonly used in practice from “Worksheet 13: Reinforcement of reinforced concrete structures according to DIN 1045-1” published by the Institute for Reinforced Concrete (Institut für Stahlbetonbewehrung e.V.).

Under construction:

By default, specter is used for LEAN planning. For this type of planning, it is recommended to use the standard values for a LEAN area. This means that the cost values for the finishing work are converted to square meters. This is standard practice, with the caveat that different cost values are assumed depending on the type of building (e.g., office or student residence).

For this standard case, it is therefore always advisable to select the gross floor area as the dimension.

If the components for the interior work are explicitly modeled, the same procedure is followed as for the components in the shell construction.

2. Typical sources of error in assignment

Use of gross values for tasks where openings are to be omitted
Incorrect assignment of volume instead of area
Use of projected floor space for complex objects

Restrictions:

Quantity determination in specter: only fixed dimensions can be selected, multiplied by a factor
Complex geometries: edge formwork, beams → approximation via factors necessary
Manual workaround possible, but time-consuming

3. Meaning of AV error messages

Error after saving a task:
“Some components do not have the specified dimension...” → Dimension missing or component not modeled correctly
Error after saving the calculation:
“Some components in the object groups do not have the necessary dimensions...” → Dimension for component empty or not available