Design-build projects involve general contractors providing project budgets based on a conceptual design provided by the owner. The general contractor's scope of work includes the development of the construction documents (drawings and specifications) necessary for construction.
Design costs for design-build projects are generally lower than traditional design-bid-build delivery methods. Additionally, value engineering can be built into the project from the initial design phase. Due to the lower cost of design-build construction documents, the contractor and/or design professionals generally retain ownership rights to the documents, and they are therefore not portable (cannot be sent for bid by other general contractors).
The design-bid-build method of project delivery involves the owner working directly with an architect and/or project engineer(s) to develop a full set of construction drawings and specifications. Bids are then solicited from several general contractors, and the project is award on the basis of several factors, including cost, reputation, projected schedule, experience, and proposed subcontractors.
The design costs of the design-bid-build method are typically higher than design-build, however the owner retains ownership of the construction plans.
DBB with construction management
Similar to design-bid-build, an owner may elect to hire a construction manager / general contractor (CMGC) either after the construction documents are completed, or often while the documents are still being developed. The CMGC agrees to construct the project for the costs of the project, plus a negotiated fee, generally on a percentage basis.
The CMGC will solicit bids from subcontractors as completed documents are available, thus allowing the construction team to be fully in place sooner and allowing for faster construction starts.
Integrated project delivery (IPD)
Integrated project delivery is a method in which the interests of the primary team members are aligned to ensure maximum performance and coordination.
According to the American Institute of Architects (AIA), "Integrated Project Delivery (IPD) leverages early contributions of knowledge and expertise through the utilization of new technologies, allowing all team members to better realize their highest potentials while expanding the value they provide throughout the project lifecycle."