Design-Build

Design-Build

The design-build (DB) process was developed to consolidate responsibility for

design and construction into a single contracting entity and to simplify the

administration of tasks for the owner (Beard et al. 2005). Figure 1–3 illustrates

this process.

In this model, the owner contracts directly with the design-build team

(normally a contractor with a design capability or working with an architect)

to develop a well-defi ned building program and a schematic design that meets

the owner’s needs. The DB contractor then estimates the total cost and time

needed to design and construct the building. After all modifications requested

by the owner are implemented, the plan is approved and the final budget for

the project is established. It is important to note that because the DB model

allows for modifi cations to be made to the building’s design earlier in the process, the amount of money and time needed to incorporate these changes is also

reduced. The DB contractor establishes contractual relationships with specialty

designers and subcontractors as needed. These are usually based on a fixed

price, lowest bid basis. After this point, construction begins and any further

changes to the design (within predefi ned limits) become the responsibility of

the DB contractor. The same is true for errors and omissions. It is not necessary

for detailed construction drawings to be complete for all parts of the building

prior to the start of construction on the foundation and early building elements.

As a result of these simplifications, the building is typically completed faster,

with far fewer legal complications, and at a somewhat reduced total cost. On

the other hand, there is little fl exibility for the owner to make changes after the

initial design is approved and a contract amount is established.

The DB model is becoming more common in the United States and is used

widely abroad. Data is not currently available from U.S. government sources,

but the Design Build Institute of America (DBIA) estimates that, in 2006,

approximately 40 percent of construction projects in the United States relied

on a variation of the DB procurement approach. Higher percentages (50 to 70

percent) were measured for some government organizations (Navy, Army, Air

Force, and GSA).

The use of BIM within a DB model is clearly advisable. The Los Angeles

Community College District (LACCD) has established a clear set of guidelines for this use of BIM for its design-build projects (see http://standards.

build-laccd.org/projects/dcs/pub/BIM%20Standards/released/PV-001.pdf).

Figure 1–3 is adapted from this paper and shows the BIM-related workflow

and deliverables for this standard.