SIA 103-K (2018) – Calculation Aid for Civil Engineering Fees
The SIA 103-K (2018) is a calculation aid published by the Swiss Society of Engineers and Architects (SIA). It serves as a supplementary document to the regulation SIA 103 (Ordnung für Leistungen und Honorare der Bauingenieure und Bauingenieurinnen). Officially titled Kalkulationshilfe zur Ordnung SIA 103, this 2018 edition replaced the previous 2014 version and has been valid since November 1, 2018. It provides a non-binding framework for estimating the time required and the resulting fees for civil engineering services in Switzerland.
The scope of this document covers the calculation of professional fees based on two primary methods: effective time expenditure and construction costs. It applies to civil engineering projects ranging from strategic planning and preliminary studies to implementation and operation. The document defines specific calculation variables, including qualification categories (A to G), levels of experience (1 to 3), and various project-specific factors such as the degree of difficulty and the team factor. It is designed for use in individual contracts, general planning mandates, or planning consortiums.
Structured into distinct articles, the document details the mathematical formulas used to predict hours required for a project. It specifically addresses requirements from the Swiss Competition Commission (WEKO) regarding the separation of mandatory regulations and statistical calculation aids to ensure compliance with antitrust laws.
Fee Calculation Based on Effective Time Expenditure
Under Article 6, fees can be agreed upon based on the actual time spent by personnel. This method is recommended for services where the scope is difficult to estimate at the outset, such as overall management, site supervision, and specialized services like expert reports or heritage conservation.
- Qualification Categories: Employees are classified into seven categories (A to G) based on their function, such as Projektleiter (Category A) or Zeichner (Category G).
- Experience Levels: Within each category, levels 1 to 3 reflect education and years of experience. Level 3 typically requires a tertiary degree and at least 5 years of experience.
- Calculation Basis: The fee is derived from the total sum of hours (Tt) multiplied by the average hourly rate (h), as defined by the formula H = Tt x h.
Fee Calculation Based on Construction Costs
Article 7 outlines the method for estimating fees relative to construction costs. This approach uses statistical data to predict the required time (Tp) based on the cost of the structural elements managed by the engineer.
- Aufwandbestimmende Baukosten (Ba): Relevant construction costs including excavation, support structures, and waterproofing, excluding VAT and financing costs.
- Schwierigkeitsgrad (n): A factor ranging typically between 0.8 and 1.2, representing the complexity of the task, risks, and required specialized knowledge.
- Team Factor (i): Accounts for the specific composition and efficiency of the deployed team.
- Adjustment Factor (r): Used to reflect local conditions, organizational influences, or specific processing efforts like working in groundwater or complex building forms.
Phase Distribution and Weighting
The document provides a standard percentage distribution (q) of the total time expenditure across the various partial phases of a project.
- Phase 31 (Vorprojekt): 8% of the total effort.
- Phase 32 (Bauprojekt): 22% of the total effort.
- Phase 51 (Ausführungsprojekt): 18% of the effort, with a 30% surcharge for structural design elements.
- Phase 52 (Ausführung): 37% of the total effort, covering general and technical site management.
Frequently Asked Questions
What is the standard value for the degree of difficulty (n)?
Unless otherwise agreed, the standard value for the degree of difficulty (n) is 1.0, though it typically ranges between 0.8 and 1.2 based on project complexity.
Which construction costs are excluded from the calculation of Ba?
Costs such as value-added tax (VAT), land acquisition, financing costs, public fees, insurance, and the engineer's own fees are excluded from the relevant construction costs (Ba).
How is the experience level 3 defined for staff classification?
Level 3 applies to employees with a completed secondary or tertiary education and at least 5 years of experience, or staff without such degrees who have at least 10 years of experience in the function.
Does the SIA 103-K provide binding hourly rates?
No, the SIA 103-K does not provide binding hourly rates; the rates (h) must be offered by the engineer and agreed upon between the parties in the contract.
How are fees handled for the repetition of identical buildings?
For the first building, the full fee is due. For subsequent identical buildings, the document recommends remuneration based on the effective time spent.
What is the team factor (i)?
The team factor (i) is used to multiply the estimated median time to calculate the project-specific predicted time, reflecting the specific deviation and quality of the team's composition.
