Anyone dealing with a German planning practice for the first time quickly hears terms such as "service phase 5", "fee zone III" or "cost group 400". Behind them sits a manageable system: HOAI, the German fee scale for architects and engineers, divides a construction project into nine steps, assigns each step a share of the fee and relates that fee to the construction costs, which DIN 276, the German standard for construction cost classification, structures into cost groups. This guide explains the connections without prior knowledge, from the first idea to billing. It does not replace legal or fee advice.
The nine service phases: how a project runs
The service phases (Leistungsphasen, LPH) are the sections of a design commission. HOAI names them officially; in everyday practice shorter names have become common. Both forms sit side by side here.
| LPH | Official name (German) | Everyday name | What happens there |
|---|---|---|---|
| 1 | Grundlagenermittlung (basic evaluation) | Basics | Clarify the task, look at the site, record needs and framework conditions. |
| 2 | Vorplanung (preliminary design) | Preliminary design | First concepts and options, coordination with the client, cost estimate. |
| 3 | Entwurfsplanung (design) | Design | The worked-through design with all specialist designers, cost calculation. |
| 4 | Genehmigungsplanung (approval planning) | Permit application | Documents for the building permit, coordination with the authority. |
| 5 | Ausführungsplanung (execution planning) | Working drawings | Detailed drawings that the building is actually built from. |
| 6 | Vorbereitung der Vergabe (preparation of contract award) | Tendering | Bills of quantities with quantities, the basis of the bids. |
| 7 | Mitwirkung bei der Vergabe (assisting the award process) | Award | Check and compare bids, award proposal, placing the order. |
| 8 | Objektüberwachung, Bauüberwachung und Dokumentation (construction supervision and documentation) | Site supervision | Supervise the site, track dates and costs, identify defects, acceptance, check invoices. |
| 9 | Objektbetreuung (post-completion support) | Post-completion support | After acceptance: inspection before the warranty period ends, follow up on defects. |
The order is no accident: each phase builds on the result of the previous one. The cost estimate from the preliminary design becomes the cost calculation in the design phase, the execution planning delivers the quantities for tendering, and site supervision checks whether what was tendered is what gets built. How phases 6 and 7 run in detail is described in GAEB tendering: from AVA to award; documentation in phase 8 is covered in Site diary duty: content and evidence.
Fee per phase: chargeable costs, fee zone, fee table
The fee of a planning practice is not an hourly rate but an amount that results from four quantities.
First, the chargeable costs (anrechenbare Kosten): the portion of construction costs the fee relates to. For buildings these are mainly the costs of the structural works (cost group 300) and, in part, the technical systems (cost group 400). The cost calculation from the design phase is decisive, or the cost estimate as a fallback.
Second, the fee zone (Honorarzone): it grades how demanding the design is. For buildings the zones range from I (very low requirements) to V (very high requirements); building services has three zones.
Third, the fee table (Honorartafel): for each service profile, that is buildings and interiors, open spaces, engineering structures, traffic facilities, structural design and building services, HOAI provides a table with reference points of chargeable costs and, per fee zone, a range from the base fee rate to the upper fee rate. If the costs fall between two reference points, the fee is interpolated linearly (§ 13 HOAI). Since HOAI 2021 these values are an orientation; the fee is agreed in text form.
Fourth, the percentage per service phase. The total fee is distributed across the phases in fixed shares. For buildings these are:
- LPH 1 basic evaluation: 2 percent
- LPH 2 preliminary design: 7 percent
- LPH 3 design: 15 percent
- LPH 4 approval planning: 3 percent
- LPH 5 execution planning: 25 percent
- LPH 6 preparation of contract award: 10 percent
- LPH 7 assisting the award process: 4 percent
- LPH 8 construction supervision: 32 percent
- LPH 9 post-completion support: 2 percent
Other service profiles use other shares; structural design only has phases 1 to 6. If a practice is commissioned with only some of the phases, it is entitled only to the corresponding share. The full calculation path with a worked example is explained in Calculate HOAI fees: zones, rates, phases; an orientation value for buildings is provided by the HOAI fee calculator.
Conversion surcharge and special services
Two items are often added to the table fee.
The conversion or modernization surcharge (Umbauzuschlag) compensates for the extra effort that arises when designing and building within existing fabric: what exists has to be surveyed, checked and incorporated into the design. HOAI 2021 provides in § 6 para. 2 for a surcharge of up to 33 percent, the level of which the contracting parties agree. No fixed rate is prescribed.
Special services (Besondere Leistungen) are services beyond the basic services of a service profile, for example a deeper condition survey, additional options, funding documents or special documentation. They are agreed separately and usually paid as a flat rate or by time, separate from the table fee. Ancillary costs, for example for travel or reproductions, are billed as a flat percentage or itemized (§ 14 HOAI).
Cost groups under DIN 276: 100 to 800
DIN 276 structures the costs of a construction project into eight cost groups. They are the shared language of clients, designers and contractors, and they determine which costs are chargeable for the fee.
- 100 Site: land value, incidental land costs, clearing.
- 200 Preparatory measures: preparing the site, access and services, temporary measures, contaminated sites.
- 300 Building, structural works: everything structural from the ground slab to the roof tile: excavation, foundations, external and internal walls, floors, roofs, built-in elements.
- 400 Building, technical systems: everything technical from the tap to the plant: drainage and water, heat supply, ventilation, power, telecommunications, conveying systems, use-specific systems, building automation.
- 500 Outdoor facilities and open spaces: ground surfaces, paved surfaces, structures and technical systems outdoors, water surfaces, planting and seeding areas.
- 600 Furnishings and artworks: movable and special furnishings, IT equipment, art.
- 700 Incidental construction costs: client tasks, architect and engineer services, surveys and consulting, general incidental costs.
- 800 Financing: financing costs and interest on borrowed capital.
Cost groups 300 and 400 are the core: they describe the building itself and form the chargeable costs for buildings. For landscape architects cost group 500 takes center stage, for building services engineers the subgroups 410 to 480, which are assigned to the eight system groups of HOAI.
What this means for billing
The four quantities and the surcharges form a chain that runs through the whole project: the cost calculation sets the chargeable costs, fee zone and fee table give the total fee, the percentage per phase distributes it, and with each completed or partly delivered phase the practice can issue an interim invoice. The final invoice consolidates all phases, surcharges, special services and ancillary costs and deducts the interim payments already made.
The documentation from site supervision belongs in the same chain: inspection reports, the site diary, defect lists and the acceptance report prove which service was delivered when. If the commission changes along the way, for example through additional design or a conversion within the conversion, a follow-up commission is needed so that the invoice matches the contract.
What Structify can do
Structify maps this chain in the project as far as calculating and documenting are concerned: fees under HOAI 2021 with Section 13 interpolation for the service profiles buildings and interiors, open spaces, engineering structures, traffic facilities, structural design and building services; percentages per service phase; conversion surcharge as a percentage the practice sets; special services as a flat rate or by time; ancillary costs as a flat rate or itemized; interim and final invoices from the project. Cost states under DIN 276 accompany the project from the cost estimate to the production costs. The documentation of site supervision, that is site inspection, site diary and defects, sits in the same project as the HOAI fee. What this looks like per practice and role is shown on the pages For whom.
What Structify does not take on: the decision which fee zone applies, which service has been commissioned and how a contract is to be read. That remains a professional and, where needed, legal assessment.
Frequently asked questions
Does a practice have to take on all nine service phases?
No. The commission can cover individual phases or parts of them, for example only the design up to the permit or only site supervision. The fee then follows the percentages of the commissioned phases.
Are the HOAI fee tables binding?
Not since HOAI 2021: the table values serve as orientation, and the fee is agreed in text form. If there is no agreement, the base fee rate is deemed agreed for basic services.
What is the difference between cost group 300 and 400?
Cost group 300 covers the structural works, roughly everything from the ground slab to the roof tile. Cost group 400 covers the technical systems, from the tap to the ventilation or heating plant.
How high is the conversion surcharge?
HOAI 2021 names an upper limit of 33 percent in § 6 para. 2; the actual level is agreed by the contracting parties depending on the effort within the existing fabric. There is no fixed rate.
Conclusion
A construction project runs in nine service phases whose fee results from chargeable costs, fee zone, fee table and the percentage per phase; conversion surcharge, special services and ancillary costs come on top. The cost groups of DIN 276 are the shared language of everyone involved. Anyone who knows this chain understands every interim invoice and can check it.