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Project Managementaka: DDaka: design development phase

Design Development

In Plain English

The phase when architectural plans are developed from rough ideas into detailed, coordinated designs.

Definition

Design development (DD) is the phase of the architectural design process that follows schematic design and precedes construction documents. During DD, the design team refines the building's size, form, systems, and materials, coordinates structural, mechanical, and electrical systems, and prepares drawings and specifications at approximately 50 to 60 percent completion. An updated cost estimate is typically prepared at the end of DD.

Why It Matters in Bidding

Design development is the phase where estimators gain enough detail to replace rough conceptual numbers with a more reliable cost model, making the DD estimate a critical budget checkpoint. Catching scope creep or a system over budget here is far cheaper than discovering it in construction documents or bidding. It also lets contractors flag constructability and long-lead procurement issues while changes are still inexpensive.

Example

At the end of design development the estimator delivers an updated estimate showing the curtain wall is running over the program budget, prompting the architect to study a lower-cost glazing system before construction documents begin.

Related Terms

Design PhaseConstruction AdministrationPreconstructionValue Engineering

Frequently Asked Questions

DD estimates are more reliable than schematic-phase numbers because systems and materials are roughly 50 to 60 percent defined, but they still carry contingency for unresolved details. Accuracy typically falls between conceptual estimating and the tight range of a detailed bid prepared from complete construction documents.
Schematic design establishes overall form, size, and basic relationships. Design development refines that concept by coordinating structural, mechanical, and electrical systems, selecting materials, and resolving dimensions. The deliverables become more detailed, which lets estimators move from broad parametric numbers toward quantity-based pricing on the major building systems.
Early contractor input during DD improves constructability, surfaces long-lead procurement risks, and aligns the design with the budget while changes are still cheap. On design-build and CM-at-risk projects this collaboration is built into the delivery method, helping avoid costly redesigns once construction documents are underway.

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