Design–bid–build

Design–bid–build (or design/bid/build, and abbreviated D–B–B or D/B/B accordingly), also known as Design–tender (or "design/tender") traditional method or hardbid, is a project delivery method in which the agency or owner contracts with separate entities for the design and construction of a project.

Design–bid–build is the traditional method for project delivery and differs in several substantial aspects from design–build.

There are three main sequential phases to the design–bid–build delivery method:

In this phase the owner retains an architect (or consulting engineer for infrastructure works) to design and produce bid documents, including construction drawings and technical specifications, on which various general contractors will in turn bid to construct the project. For building projects, the architect will work with the owner to identify the owner's needs, develop a written program documenting those needs and then produce a conceptual and/or schematic design. This early design is then developed, and the architect will usually bring in other design professionals including mechanical, electrical, and plumbing engineers (MEP engineers), a fire protection engineer, structural engineer, sometimes a civil engineer and often a landscape architect to help complete the construction drawings and technical specifications. The finished bid documents are coordinated by the architect and owner for issuance to general contractors during the bid phase.

Design fees are typically between 5-10% of the total project cost.

Bidding can be "open", in which any qualified bidder may participate, or "select", in which a limited number of pre-selected contractors are invited to bid.

The various general contractors bidding on the project obtain copies of the bid (or tender) documents, and then put them out to multiple subcontractors for bids on sub-components of the project. Sub-components include items such as the concrete work, structural steel frame, electrical systems, HVAC, and landscaping. Questions may arise during the bid (or tender) period, and the architect will typically issue clarifications or corrections to the bid documents in the form of addenda. From these elements, the contractor compiles a complete bid (or "tender price") for submission by the establish closing date and time (i.e., bid date). Bids can be based on the quantities of materials in the completed construction (e.g., as in the UK with bills of quantities), the operations needed to build it (e.g., as in operational bills), or simply as a lump sum cost; however, these bid requirements are elucidated within the bid documents.

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