Cost calculation
When calculating costs in the building industry, the "costs on the basis of the draft planning " according to DIN 276 costs in building are determined. The cost calculation with the underlying advanced planning offers a more precise cost determination than the cost estimate preceding in the planning process . Your result represents a basis for decision-making about the continuation of the project after the draft planning to the next stage of the approval planning (see service phases according to HOAI ). In construction, an accuracy of ± 20% is typically expected from a cost calculation.
The cost calculation is based on the worked through design drawings and the quantity calculations. If necessary, detailed plans and descriptions of such details are included that cannot be seen from the drawings and the calculation documents. According to DIN 276: 2018-12, the cost calculation must be specified at least up to the 3rd level of the cost breakdown. In DIN 276-1: 2008-12, creation was only required up to the second level.
There are two methodological approaches to implementation:
- Distribution of the costs that were determined in the context of the cost estimate to the cost groups of the second level (components).
- Determination of the "quantities to be built" according to the component catalog. The component “outer walls” of cost group 330 is named as an example. Using cost indicators (e.g. € / m³ or € / m²) from comparable projects, the costs for the new project are calculated and the specific quality standard is taken into account. This procedure is to be agreed separately as part of a planning order and is therefore to be paid for in addition.
The billing of this service is regulated in the fee schedule for architects and engineers (HOAI) in § 15 under description of the service profile of the draft planning: A cost calculation is to be carried out according to DIN 276 or according to the law of housing calculation. As a special service - which are paid for separately - a "cost calculation by setting up quantity structures or component catalog" is provided.
Extract from ÖNORM B 1801-1 with reference to the cost calculation:
- Phase: design phase
- Objective: Specification of costs for the cost estimate and as a cost control
- Basics: Design planning with information about types of use and rooms with information on quantities (e.g. room areas, room contents)
- Structure: planning-oriented - element and execution-oriented - performance group
Individual evidence
- ↑ a b Bernd Kochendörfer, Jens H. Liebchen, Markus G. Viering: Construction project management: Basics and procedures. (Guide of the construction company and the construction industry). 4th edition. Vieweg & Teubner Verlag, 2010, ISBN 978-3-8348-0496-9 .