Construction management is the moment when architecture ceases to be a drawing and begins to become a reality. HOAI Service Phase 8 describes precisely this transition: It encompasses site supervision and overall construction management—that is, the phase during which the architect is present on the construction site, ensuring quality, controlling costs, and coordinating schedules. Anyone who underestimates this service phase risks not only defects in the structure but also significant legal and financial consequences for all parties involved.

• What HOAI Service Phase 8 encompasses in terms of legal requirements and scope, and how it differs from other service phases
• Which basic and special services are included in project supervision
• How on-site supervision, construction management, and specialized construction management are related and differ
• What obligations the architect has during construction supervision and the extent of their liability
• How quality assurance, schedule monitoring, and cost control work in practice
• What role acceptance, notices of defects, and documentation play in Service Phase 8
• How the fee for Service Phase 8 is calculated and what percentage it represents of the total fee
• What typical errors and misunderstandings arise in construction supervision and how to avoid them

What is HOAI Service Phase 8? Definition and Classification

The Fee Schedule for Architects and Engineers (HOAI) divides the services involved in building design into nine service phases. HOAI Service Phase 8 is officially designated “Construction Supervision and Documentation” and is thus the most comprehensive and, in practice, the most demanding of all service phases. It begins immediately after the construction contract is awarded—that is, upon completion of Service Phase 7—and ends with the formal acceptance of the structure and the final documentation. Its core task is to monitor the execution of the construction project to ensure compliance with the approved plans, the agreed-upon quality standards, and the relevant technical regulations.

The HOAI distinguishes within each service phase between basic services and special services. Basic services are those activities considered indispensable for the proper fulfillment of the planning contract and are covered by the agreed-upon fee. Special services go beyond this and must be commissioned and remunerated separately. This distinction is particularly significant for Service Phase 8 because the scope of construction supervision varies greatly in practice, and the boundary between basic services and additional services can be the subject of legal disputes in the event of a conflict.

Within the system of nine service phases, Service Phase 8 occupies a special position: It is the only phase that takes place entirely on the construction site and depends directly on the quality of the preceding planning phases. Errors in the construction planning (Service Phase 5) or gaps in the bidding process (Service Phases 6 and 7) become apparent in Service Phase 8 and must be addressed there. At the same time, it is the phase in which the groundwork is laid for Service Phase 9 (project supervision), because careful documentation and a properly conducted acceptance form the basis for subsequent warranty claims.

Basic Services of Project Supervision: What the Architect Is Required to Provide

The basic services for HOAI Service Phase 8 are detailed in the HOAI service description. They primarily involve monitoring the construction of the project to ensure compliance with the building permit, the construction drawings, and the specifications. The architect verifies whether the contractors are adhering to the agreed-upon materials, construction methods, and construction details. This may sound self-evident, but in practice it is a complex, ongoing task because dozens of decisions are made daily on a construction site that influence the final result.

Quality assurance includes verifying the dimensional accuracy of the structure—that is, checking whether dimensions, center distances, elevation marks, and slope specifications match the plans. Deviations detected early can still be corrected; conversely, dimensional errors discovered late may require costly demolition work or lead to permanent limitations on usability. Another core service is monitoring the construction of structural systems of low complexity to ensure they comply with the structural stability analysis. For complex structural systems, however, a separate inspection engineer or structural engineer must be engaged, whose services are commissioned independently.

The coordination of the technical specialists involved in project supervision is another basic service. In a modern construction project, numerous specialist planners work alongside the architect: structural engineers, engineers specializing in building services (heating, ventilation, plumbing, electrical), specialist site managers for specific trades, and, if necessary, experts in fire protection or building physics. In Service Phase 8, the architect assumes the role of coordinating construction manager, overseeing the interfaces between these parties and ensuring that design changes made by a specialist planner do not lead to conflicts with other trades.

Cost control and schedule monitoring are also part of the basic services. The architect compares the actual costs incurred with the cost estimate from Service Phase 6 and immediately informs the client if any deviations become apparent. The same applies to the schedule: Delays in individual trades can block subsequent work and trigger contractual penalties. The architect must identify and communicate these risks early on, even if he or she is not a contracting party to the contractors.

Acceptance and Defect Management

One of the most important basic services of HOAI Service Phase 8 is participation in the acceptance of the construction work. Acceptance is a central legal concept in German construction law: it marks the moment when the client acknowledges the contractor’s work as being in accordance with the contract. Upon acceptance, the burden of proof for defects shifts from the contractor to the client, and the warranty periods begin to run. The architect prepares for the acceptance, oversees the process, and prepares an acceptance report documenting any identified defects and reservations.

Prior to acceptance, the architect is obligated to inspect the structure for apparent defects and to notify the contractor of them. Defects that would have been apparent during a thorough inspection but were not reported can later be asserted only under more stringent conditions. The notice of defects must be submitted in writing and must set a reasonable deadline for rectification. The architect then verifies whether the defects have actually been remedied and documents the result. This task requires that the architect be familiar with the technical requirements of the relevant trades and be able to assess whether the corrective work was performed properly.

Overall Construction Management, Construction Management, and Specialized Construction Management: Who Is Responsible for What?

In practice, the terms “overall construction management,” “construction management,” and “specialized construction management” are often used interchangeably, even though they describe different levels of responsibility. Overall construction management is the highest level of coordination, which the architect assumes as the general planner. It encompasses the overall coordination of all specialist planners and specialist construction managers, monitoring compliance with schedules and budgets at the project level, and communication with the client. Overall construction management is a basic service under HOAI Service Phase 8, to the extent that it is required within this framework.

On-site construction management, on the other hand, refers to the physical presence at the construction site, the regular monitoring of ongoing construction work, and direct communication with the foremen and site managers of the contracting firms. It is also a basic service, but its scope depends on the complexity of the project and the progress of construction. The architect does not have to be permanently present on the construction site, but must be present frequently enough to identify defects in a timely manner. How often this occurs depends on the progress of construction: During critical phases—such as when pouring concrete slabs, installing waterproofing, or assembling complex facade elements—close monitoring is required.

Specialized construction supervision is carried out by the respective specialist designers for their respective trades. The specialized construction supervisor for heating, ventilation, and plumbing monitors the execution of the building services to ensure compliance with their technical designs, while the structural engineer monitors the execution of the structural work. These specialist construction management roles are not services provided by the architect but rather separate engagements of the respective specialist planners. The architect coordinates them but is not responsible for the technical details unless he or she has personally undertaken the specialist planning.

Liability and Duties of Care in HOAI Service Phase 8

From a liability perspective, HOAI Service Phase 8 is the riskiest phase for the architect. Errors in construction supervision can directly lead to construction defects that are costly to remedy and for which the architect is jointly and severally liable alongside the contractor. Joint and several liability means that the client can claim full compensation for the damage from any one of the parties involved without having to concern themselves with the internal allocation of responsibility. The architect against whom a claim is made must then, if necessary, seek recourse against the contractor.

The scope of the architect’s supervision obligation has been clarified by extensive case law. As a general rule, the architect is not required to supervise every single action, but must establish a system of control suitable for detecting defects in a timely manner. For simple, routine work carried out by experienced specialized contractors, random spot checks are sufficient. For difficult, error-prone, or safety-critical work, more intensive supervision is required. If the architect knows or should know that a contractor is experiencing difficulties or has made mistakes in the past, the architect must increase the frequency of inspections accordingly.

Particular care is required for concealed work: these are components that are no longer visible after completion, such as waterproofing under floor slabs, reinforcement before concrete pouring, or thermal insulation behind cladding. If the architect fails to inspect these works before they are concealed, he loses the opportunity to identify defects. Case law is strict in this regard: Anyone who fails to inspect concealed work in a timely manner cannot claim, in the event of damage, that they were unaware of the defect. For this reason, it is good practice to systematically document concealed work before it is covered, using photographs, measurement sketches, and notes in the inspection reports.

Documentation: The Underestimated Foundation of Construction Supervision

In HOAI Service Phase 8, documentation is not merely a formal obligation but a central tool for quality assurance and legal protection. The architect maintains a construction log in which key events on the construction site are recorded: weather conditions, the number of workers per trade, construction progress, special occurrences, instructions given, and defects identified. In the event of a dispute, the construction log serves as important evidence demonstrating when the architect was on site, what he inspected, and what measures he took.

In addition to the daily construction log, photographic documentation, minutes of construction meetings, written instructions to contractors, and quantity survey reviews are part of the documentation for Service Phase 8. Minutes of construction meetings are particularly important because they record decisions and agreements that were made verbally. What is not documented in writing often does not exist in the event of a dispute. The architect should therefore insist that all essential agreements be confirmed in writing, even if this is sometimes perceived as bureaucratic in the day-to-day routine of a construction site.

The final documentation at the end of Service Phase 8 comprises a compilation of all as-built drawings—that is, the plans that reflect the actual condition of the structure as completed (so-called as-built drawings or “as-built” documentation). These documents are essential for the operation and future maintenance of the building. If they are missing, the building owner will incur significant additional costs during later renovation work or in the event of damage. The compilation of as-built documentation is a core service of HOAI Service Phase 8, even though the preparation of the as-built drawings themselves is often performed by the contractors.

Fee for Service Phase 8: Weighting and Calculation

The HOAI allocates a fee share of 32 percent of the total fee for building design to Service Phase 8. This is by far the highest percentage of all nine service phases and reflects the actual effort involved: Construction supervision ties up significant personnel resources over a long period of time and requires a continuous presence on the construction site as well as intensive communication with all parties involved. By comparison: Conceptual design (Service Phase 3) receives 15 percent, and detailed design (Service Phase 5) receives 25 percent.

The fee for Service Phase 8 is calculated according to the general rules of the HOAI: The basis consists of the billable costs of the construction project, the fee zone (which reflects the project’s level of difficulty), and the agreed-upon fee rate within the minimum and maximum rates specified in the HOAI tables. The billable costs essentially correspond to the costs of cost groups 300 (building, structural works) and 400 (building, technical systems), although cost group 400 is only applied at a certain percentage unless the architect also handles the specialized planning for the building’s technical systems.

In practice, the issue of fees for Service Phase 8 is often a source of misunderstanding. Some clients assume that the architect is obligated to make an unlimited number of site visits as part of the agreed-upon flat-rate fee. This is incorrect: The scope of construction supervision is determined by what is necessary for the proper fulfillment of the basic services. Services that go beyond this scope—such as particularly intensive monitoring due to quality issues with a contractor or the supervision of substantial additional work—may be compensated separately as special services.

Common Errors and Misunderstandings in Construction Supervision

One of the most common errors in the practical application of HOAI Service Phase 8 is the unclear delineation of responsibilities between the architect, technical construction managers, and the site manager of the contracting company. If it is not specified in writing from the outset who performs which inspections and who is to be notified in the event of deviations, gaps arise that no one wants to fill in the event of damage. A clear communication structure, agreed upon at the start of construction and communicated to all parties involved, is not a bureaucratic exercise but a practical necessity.

Another common misunderstanding concerns the architect’s authority to issue instructions to the contractors. The architect is not a contractual partner of the contractors but rather an agent of the client. The architect may issue instructions, but only within the framework of the construction contract concluded between the client and the contractors. If the architect orders work that goes beyond the contractually agreed scope, the contractors will have claims for additional compensation against the building owner. The architect must therefore always verify whether an instruction is covered by the existing contract and inform the building owner if additional costs might arise.

Finally, the importance of formal acceptance is often underestimated in practice. Some building owners begin using a building without having carried out a formal acceptance because the move-in date is approaching or because minor remaining work is still pending. This is problematic from a legal standpoint: Implied acceptance—that is, tacit acknowledgment of the work’s completion through commencement of use—can result in known defects being deemed approved and warranty periods beginning without all defects having been documented. In such situations, the architect should insist on a formal acceptance with a complete report, even if this entails additional organizational effort.

Service Phase 8 as a Litmus Test for Planning Quality

HOAI Service Phase 8 is far more than an administrative task accompanying construction. It is the moment when it becomes clear whether the preceding planning was complete, coordinated, and ready for execution. Incomplete construction drawings, unclear scope of work descriptions, or unresolved interface conflicts between trades become immediately apparent on the construction site and create a need for clarification that costs time and money. Careful planning during Service Phases 1 through 7 is therefore the best preparation for a smooth Service Phase 8.

For the architect, Service Phase 8 entails a special responsibility: he stands between the client, whose interests he represents, and the contractors, whose work he supervises. This dual role requires expertise, assertiveness, and communication skills in equal measure. Anyone who lacks authority on the construction site, fails to identify technical defects, or is unable to resolve conflicts constructively will fail in service phase 8, regardless of how well the preceding planning was done.

The 32 percent fee weighting that the HOAI assigns to Service Phase 8 is no coincidence. It reflects decades of experience with the actual effort involved and the true significance of construction supervision. Anyone who carries out this phase carefully, with proper documentation, and with expertise not only delivers a building with few defects to the client but also provides a solid foundation for operation, maintenance, and, if necessary, future renovations. That is the true value of HOAI Service Phase 8: It ensures not only the quality of the structure but also the long-term benefit of the entire planning process.