Design-build focuses on combining the design, permit, and construction schedules in order to streamline the traditional design-bid-build environment. This does not shorten the time it takes to complete the individual tasks of creating construction documents (working drawings and specifications), acquiring building and other permits, or actually constructing the building. Instead, a design-build firm will strive to bring together design and construction professionals in a collaborative environment to complete these tasks in an overlapping like fashion i.e. construction has begun while the building is still being designed.

Typically the hallmark of a Design/Build project is that one organization is responsible for both design and construction of the project.

Benefits of Design-Build
It is important to note that the design-build method, while not focused on saving the owner construction costs, nonetheless often saves the owner money on the overall project. Providing an earlier owner occupancy date usually yields considerable overall value to the project and may make seemingly unfeasible projects into genuine opportunities.

The compression is an important aspect of the implementation of this system. Other potential attributes include:
    Enhanced communication between the service provider and the client,
    Increased accountability by the service provider,
    Single source project delivery, and
    A value based project feedback system

Enhanced Communication
Because the design parameters of a project are being developed along with the budgetary goals – construction methodologies and budget conditions being weighed simutaneously – a project is more likely to be realized than with a pure design approach. The owner has greater access to the project “team” as the project is being developed. This efficiency is not a negative “short cut” as a rule, but rather the keystone to the success of the Design&Build model.

Accountability
Rather than a parcelized level of responsibility of the classic design-bid-build, design-build provides an integrated solution for the owner or client. This moves projects away from the “finger-pointing” that is often commonplace in contemporary construction projects, and allows the owner to look to one entity with any questions or concerns.

Single Source
Instead of having several contractors and consultants, an owner has just one entity to deal with. Design revisions, project feedback, budgeting, permitting, construction issues, change orders, and billing can all be routed through the design-build firm. This single point of contact allows a certain degree of flexibility for the owner. Most design-builders will leverage that flexibility for the owner’s benefit by continually refining the construction program to maximize the owner’s value at the completion of the project.

Value-based project feedback
Typically, in order for a contractor to bid on a project, very specific details relating to the methods and materials must be given to avoid any ambiguity and to make an “apples to apples” comparison of bids. In a design-build context, the owner, the owner’s other consultants, and the design-builder can work together to determine what methods and materials will maximize the owner’s value. In instances where marginally more expensive materials, designs, or construction methods might yield a higher return on investment for the owner than those of lower cost, the owner is free to adjust the project’s program without having to re-bid the entire project.

Almost 70% of traditional contracts end up over budget, compared to D&B which is only around 25-30% over budget. The overage of a D&B project is generally owner driven, whereas the overage in the more traditional method tends to be a result of the budget disconnect to which many architects and other design professionals are prone.

(Source: Design Build Institute of America & Wikipedia)