Lead Consulting and HOAI: An Overview of Service Phases, Contracts, and Fees

The HOAI is a statutory regulation that defines the basis for the compensation of architectural and engineering services in Germany. It provides binding guidelines on which services are considered basic services, how they are structured, and what fees may be charged for typical planning tasks.

Brief Definition and Legal Framework

The HOAI specifies:

• Service categories (e.g., building, structural system, technical systems)
• Service phases (Phases 1–9)
• Basis for calculating fees
• Basic services vs. special services
• Scopes of application and legal requirements

Since the 2019 ECJ ruling, minimum and maximum rates are no longer binding. However, the HOAI continues to serve as a structural and qualitative framework of reference to which planning partners refer.

Significance for Architects, Engineers, and General Planners

The HOAI is particularly relevant for Lead Consulters because it:

• clearly defines the planning structure and responsibilities,
• describes the services provided by the individual disciplines,
• enables a comparable and transparent calculation of fees,
• establishes consistent communication between the client and the planners.

The HOAI thus provides the regulatory framework on the basis of which diverse planning services can be combined into an integrated overall package.

The HOAI divides planning services into nine phases. During the Lead Consulting  phase, these are synchronized between architecture, building services, structural engineering, fire protection, and other disciplines—a key advantage of integrated planning.

HOAI Phases 1–9 Explained Briefly (with a Focus on Integrated Planning)

1. Preliminary Planning (Phase 1) – Clarification of requirements, definition of objectives, analysis of framework conditions.
2. Preliminary Planning (LP 2) – Development of initial concepts, comparison of alternatives, cost estimation.
3. Design Planning (LP 3) – Refinement of the planning concept; functional and technical solutions.
4. Permit Planning (LP 4) – Preparation of all documents required for permits.
5. Construction Planning (Phase 5) – Detailed, construction-ready planning for all trades.
6. Preparation for Contracting (Phase 6) – Bills of quantities and specifications, tender documents.
7. Assistance with the Bidding Process (Phase 7) – Evaluation of bids, recommendations for awarding contracts.
8. Project Supervision (Phase 8) – Construction supervision, quality assurance, and coordination of construction work.
9. Project Support (Phase 9) – Documentation, warranty tracking, and optimizations.

Specialized Disciplines in Lead Consulting

Lead Consulting combines HOAI service phases from several specialized fields:

• Building/Architecture
• Structural Engineering / Structural Analysis
• Technical Building Systems (TGA) – HVAC, Electrical, Plumbing, Building Automation
• Outdoor facilities or transportation facilities (if required)
• Fire protection, BIM management, process and media planning (if agreed upon as special services)

This coordinated integration is particularly crucial in industrial, pharmaceutical, or logistics projects, as technical processes and building structures are closely interlinked.

The fee for Lead Consulting is typically composed of the fees for the relevant HOAI service categories (e.g., building, structural engineering, building services). It is based on:

• billable costs
• fee zones
• Percentage rates per service phase
• agreed-upon special services (e.g., BIM, simulations)

In this way, the HOAI establishes a transparent basis that is understandable to building owners.

Lead Consulting Contract vs. Individual Planner Contract

In a Lead Consulting contract, the services of all specialized trades are bundled into a single contract.
Advantages:

• a single point of contact for all planning disciplines
• coordinated scopes of work
• lower interface risks
• clear responsibilities

In contrast, with individual planning contracts, the client must manage multiple contracts in parallel—which involves greater coordination efforts and more coordination risks.

2019 ECJ Ruling and Current Practice

Since the ECJ ruling, the fee rates set forth in the HOAI are no longer binding.
In practice, this means:

• greater flexibility in fee agreements
• The HOAI continues to serve as a guideline and quality framework
• A combination of HOAI principles and project-specific service models

Lead Consulters , in particular, are using this flexibility to define package solutions that go beyond traditional HOAI services.