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.
Once bids are received, the architect typically reviews the bids, seeks any clarifications required of the bidders, investigates contractor qualifications, ensures all documentation is in order (including "bonding if required), and advises the owner as to the ranking of the bids. If the bids fall in a range acceptable to the owner, the owner and architect discuss the suitability of various bidders and their proposals. The owner is not obligated to accept the lowest bid, and it is customary for other factors including past performance and quality of other work to influence the selection process. However, the project is typically awarded to the general contractor with the lowest bid.
In the event that all of the bids do not satisfy the needs of the owner, whether for financial reasons or otherwise, the owner may choose to reject all bids. The following options become available to the owner:
Once the construction of the project has been awarded to the contractor, the bid documents (e.g., approved construction drawings and technical specifications) may not be altered. The necessary permits (for example, a "building permit) must be achieved from all jurisdictional authorities in order for the construction process to begin. Should design changes be necessary during construction, whether initiated by the contractor, owner, or as discovered by the architect, the architect may issue sketches or written clarifications. The contractor may be required to document "as built" conditions to the owner.
In most instances, nearly every component of a project is supplied and installed by sub-contractors. The general contractor may provide work with its own forces, but it is common for a general contractor to limit its role primarily to managing the construction process and daily activity on a construction site (see also "construction management).
During the construction phase the architect also acts as the owner's agent to review the progress of the work as it relates to pay requests from the Contractor, and to issue site instructions, change orders (or field orders), or other documentation necessary to facilitate the construction process and certify that the project is built to the approved construction drawings.