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Design-build puts design and construction under one contract with one contractor. Design-bid-build keeps them sequential and separately contracted. For a federal project, neither method is automatically faster or cheaper: compare how clearly the agency can define the work, the value of overlapping design and construction, the effort required of competing teams, and the agency’s capacity to run the procurement.
How the two delivery methods differ
| Method | Contract structure | Typical sequence | What the structure means for the agency |
|---|---|---|---|
| Design-build | One contract with one contractor for design and construction. | Design and construction may overlap, depending on project requirements and execution. | The agency competes for a team responsible for both completing the design and constructing the project. |
| Design-bid-build | Separate contracts for design services and construction. | The design is completed before construction is solicited and undertaken. | The construction competition is based on completed design documents. |
The Federal Acquisition Regulation (FAR) defines design-build as “combining design and construction in a single contract with one contractor” (FAR 36.102). FAR 36.102 defines design-bid-build as the traditional method in which design and construction are sequential and separately contracted.
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How federal design-build selection works
For a federal contract to design and construct a public building, facility, or work, FAR 36.104 directs contracting officers to use two-phase selection when they determine it is appropriate, unless the agency uses design-bid-build or another legally authorized procedure. Design-build is therefore an option to assess, not a mandatory method for every federal construction project.
What the contracting officer assesses
FAR 36.301 calls for an assessment of whether two-phase selection fits the project. Its factors provide a practical comparison checklist:
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- Whether at least three offers are anticipated.
- How much design work offerors must do before submitting price or cost proposals, and whether that work would impose substantial proposal expense.
- How fully the project requirements are defined.
- The project’s time constraints.
- The capability and experience of potential contractors.
- Whether the process is suitable and the agency can manage it.
What happens in the two phases
- Set the solicitation approach. The agency may cover both phases in one solicitation or issue two solicitations in sequence.
- Evaluate phase-one submissions. The agency assesses technical approach and qualifications, including the team’s specialized experience, capability, and past performance. Price-related factors are excluded at this stage.
- Advance a limited pool. The solicitation states the maximum number of offerors that may proceed. Under the FAR, that number normally cannot exceed five; a larger pool requires an exception process and supporting documentation.
- Request detailed phase-two proposals and select a contractor. The agency seeks detailed proposals from the firms that advanced and awards one contract using competitive negotiation.
The scope of work may establish criteria and preliminary design, budget parameters, and schedule or delivery requirements. Those boundaries define the agency’s needs while leaving the design-build team to complete design and construction under its contract.
Additional DoD limit
For Department of Defense procurements, consult the applicable DFARS provision as well as the FAR. The DFARS page identified as Change Number 5/7/2026, effective May 7, 2026, states that for contracts above $5.5 million, the phase-two pool generally may not exceed five. Exceptions apply to qualifying indefinite-delivery indefinite-quantity design-build contracts, or when an authorized official approves and documents a larger pool for an individual solicitation. Applicability depends on the specific procurement.
How to choose between the methods
Start with how well the agency can define the work
FAR 36.301 explicitly makes the extent to which requirements are adequately defined a selection factor. If the agency wants to finish and review a detailed design before seeking construction bids, the sequential design-bid-build structure may better match that preference. If it can define the required outcomes and constraints while leaving the team to complete design, design-build may fit.
Test whether schedule overlap has real value
Time constraints are also an express FAR factor. Design-build can allow design and construction activities to overlap, but that possibility is not a schedule guarantee. Its value depends on the project’s scope, approvals, interfaces, and execution. Compare the actual critical path and approval needs rather than treating overlap alone as proof of acceleration.
Account for the cost of competing
Estimate the design effort teams must provide before price or cost proposals. FAR calls out both that work and substantial proposal expense because a demanding competition can affect the practicality of the selection process. The agency should consider whether its requirements and phase-one evaluation can distinguish capable teams without requiring disproportionate unpaid design effort.
Match the process to agency capacity and team capability
The agency must be able to evaluate qualifications and technical approach, administer the phases, and manage the resulting contract. FAR identifies contractor capability and experience as well as the agency’s ability to manage the process. A delivery method is only a sound fit if the project team on both sides can carry out its responsibilities.
Set cost and schedule measures before award
Define how the agency will track original and revised cost and schedule baselines, final cost, and final completion. Keep the original baseline visible alongside later revisions so that changes do not obscure the project’s full performance history.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What the performance evidence says—and does not say
Available comparisons are tied to historical highway projects and limited samples; they do not establish a universal winner for federal buildings or other construction. The Federal Highway Administration’s 2005 Design-Build Effectiveness Study examined the Federal-aid highway program, using project surveys and a limited set of similar design-bid-build projects. Its executive summary reported design-build projects were shorter by 9 percent in total project duration and 13 percent in construction-phase duration in that comparison. The study also reported that cost effects varied with project type, complexity, and size.
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A related review of that historical evidence reported an average duration of 583 days for design-build versus 1,215 days for design-bid-build across 14 observations. In the six observations used for cost comparison, it found no significant difference in mean cost. These small, historical comparisons should not be used as a forecast for a new project.
A 2019 Government Accountability Office review of General Services Administration major construction projects offers a separate lesson about reporting, not a delivery-method comparison: GSA rebaselined 25 of the 36 projects GAO reviewed for fiscal years 2014–2018. The review does not show that either design-build or design-bid-build caused those project outcomes.
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