Design-build (DB) is the most common construction delivery approach in the private construction sector, where a construction firm is solely responsible for both the design and execution of a construction project simultaneously, normally on a fixed price lump sum basis. The design-builder, typically an experienced GC or architect, maintains a full team of design and contracting professionals and collaborates with the client/owner to design and spec the building. The design-build contract between the client and GC gives the design-builder complete control over construction projects.
In a design-bid-build (DBB) arrangement, the project owner contracts an architect to produce a conceptual design, bid documents and specs. General contractors are then invited to bid on the project, with the winner awarded a separate construction contract. The GC is responsible for recruiting, managing, and compensating all subcontractors through open bidding. Since the design is finalized without collaboration with the GC, this approach tends to lead to costly reworks and delays.
Under the construction manager at risk (CMAR) approach, a developer engages and consults a development manager to provide cost feedback during the design process, who then usually acts as the general contractor. A guaranteed maximum price contract is negotiated based on the as-yet-completed design to include the construction manager’s estimate of the remaining design features and the construction work. CMAR allows for good cost estimating at the planning stage and faster transition from design to implementation, but typically at the cost of transparency.
The delivery method chosen depends on the developer's project strategy, degree of involvement, control over, and accountability for the construction process. Regardless of the method, the developer retains overall responsibility for the project.
