When undertaking construction, renovation, demolition, or building life-extension projects—such as office buildings or industrial facilities—it is essential to engage specialized contractors. No single procurement strategy suits all projects. Today, a variety of PDMs are available, enabling clients to select the most appropriate strategy based on their specific requirements and overall project objectives.

A construction project is typically divided into two primary phases: 1) the design phase, where the building is conceptualized and planned, and 2) the construction phase, where the physical work is carried out.

When considering PDMs, differences arise based on how contractors are appointed during the design and construction phases, and how the project is carried forward through each stage.

The Design-Bid-Build (DBB) method is a procurement approach in which the design and construction phases are contracted separately. Typically, the client first engages an architectural or design firm to develop the project plans. Once the design is finalized, the construction work is tendered out to a contractor through a competitive bidding process.

Advantages:

・The design is developed by a specialized design firm, allowing for greater emphasis on aesthetics, functionality, and performance.

・Competitive bidding enables cost comparison among multiple contractors, helping the client select the most suitable construction company.

Considerations:

・Since the contractor is not involved during the design phase, their practical insights and construction expertise cannot be incorporated early on. This may result in discrepancies between the estimated design cost and actual construction bids.

・Designers are not financially accountable for construction costs, which can lead to overdesign or specifications that exceed the client’s budget or needs. Careful coordination is required to ensure the design remains cost-effective and aligned with project goals.

The Design-Build (DB) method is an integrated project delivery approach in which both design and construction services are contracted to a single entity. Depending on the project scope and strategy, the client may engage the DB contractor from the conceptual design phase, or alternatively, commission a design firm for the basic design and then engage a construction company for detailed design and execution.

Advantages:

・The contractor’s technical expertise and construction know-how can be incorporated from the early design stages, enabling more practical, cost-effective, and high-quality solutions.

・Early involvement and streamlined coordination between design and construction teams can significantly reduce the overall project timeline.

・Cost fluctuations are minimized, as the contractor is responsible for both design and construction, allowing for better cost control and predictability.

Considerations:

・Since the entire process is managed by a single entity, clients cannot solicit competitive bids for the construction phase, limiting opportunities for cost savings through price competition.

・The client must have sufficient technical capability or engage a third-party consultant to monitor quality and compliance with project standards.

The roles and responsibilities of design firms and contractors vary depending on the chosen PDM. This section explores the critical factors to consider when selecting the most appropriate method for the specific project.

In construction projects, selecting the right PDM should reflect the client’s overall policy, financial capacity, and scheduling needs.

For example, if the client prioritizes design quality, building performance, or wishes to delegate design work to a design firm, the DBB method is worth considering.

On the other hand, if avoiding budget overruns and delays is a key concern, methods such as DB or Early Contractor Involvement (ECI) can help reduce those risks. These approaches allow for early input on procurement and construction planning during the design phase, making it easier to manage costs and shorten the overall project duration.

It’s also important to select a PDM that suits the nature of the project and the characteristics of the building to be constructed.

For example, the DB method allows construction expertise to be incorporated into the design, which can result in higher construction quality and precision. However, since the contractor also bears cost-related risks during the design phase, there’s a possibility that the design may lean too much toward construction efficiency—potentially compromising the intended aesthetics, functionality, or performance.

Therefore, for public buildings, specialized facilities, or projects where design quality is critical—or when working with contractors who have limited experience—the DBB method, where design is commissioned to a design firm, should also be considered.

PDMs in construction have become increasingly diverse to reflect the varying policies and priorities of clients. Each method has its own strengths and limitations, so it’s essential to clearly define the project’s characteristics and strategic priorities before choosing the most suitable approach.