Additional construction costs are an element of total construction costs that are essential to build a building. Like the pure construction costs, additional construction costs are among the production costs of a building.1 The components of additional construction costs are recorded both in DIN 276 under the main group 700 and in section 8 of the Second Calculation Regulation. In terms of content the two definitions are roughly the same. Additional construction costs essentially include the following items:
A further definition of additional construction costs can be found in section 22 of the Immobilienwertermittlungsverordnung (ImmoWertV – German Property Valuation Ordinance). This stipulates that in calculating the fair value in line with the asset value method, the “typically incurred additional construction costs, especially the cost of planning, construction execution, regulatory reviews and approvals” must be taken into account. Experience values are therefore included in the calculation of fair value in line with this definition. These can be found, for example, in the 2000 Building Replacement Costs (NHK 2000). This method therefore differs from that in line with DIN and the Second Calculation Regulation, in which the costs actually incurred are calculated.
Additional construction costs differ depending on location and time. Furthermore, their amount depends on the respective type of building and features. They are usually expressed as a percentage of the construction costs.3 The literature publishes average experience values of between 8% and 22% of construction costs for this.4