Design Development Is Where the Schematic Design Gets Real - All the Big Decisions Are Made
Schematic design establishes the concept - the organization, massing, and character of the building. Design development takes that concept and resolves it into a fully coordinated, fully dimensioned, fully systems-integrated building that can be priced with reasonable accuracy and developed into construction documents. By the end of DD, the architect should have made and the owner should have approved every significant design decision: the final floor plate sizes and layouts, the structural system, the MEP system types, the exterior wall assemblies, the major materials and finishes, and the site design. DD is the most decision-intensive phase of the project, and it is the phase where scope creep is most likely if the owner-architect relationship does not include clear approval processes at DD milestones. The ARE PjM and PDD exams both test DD phase services and deliverables.
What Is Resolved in Design Development
The design development phase resolves: Floor plan layouts: All rooms are defined, dimensioned, and coordinated with structural bays and MEP clearances. Structural system: The structural engineer develops the framing system - member sizes, bay spans, column locations, foundation type - to the point where the system can be priced and its space requirements are known. MEP systems: The mechanical, electrical, and plumbing engineers develop their systems - equipment selections, major duct and pipe routing, electrical room locations, generator capacity - to the point where spatial requirements are fixed and the major equipment can be priced. Building envelope: Exterior wall assemblies, window types, roof system, and envelope performance characteristics are selected and specified at the DD level. Interior finishes and major materials: The primary finish palette - flooring types and locations, ceiling systems, primary wall finishes, millwork design - is selected and shown on DD drawings.
DD Deliverables
The DD package delivered to the owner for review and approval typically includes: architectural plans at a meaningful scale (1/8" = 1'-0" or 1/4" = 1'-0" for most spaces); building sections; exterior elevations with material designations; wall sections showing envelope assembly details in sufficient detail to confirm the assembly approach; outline specifications identifying the specified systems and major products for each specification section; structural engineering drawings at the DD level; MEP engineering drawings at the DD level; and an updated cost estimate (typically a more detailed quantity take-off or parametric estimate than the SD estimate, reflecting the more fully developed design).
Key Exam Points
- DD resolves: all major design decisions - structural system, MEP types, envelope assemblies, major finishes.
- DD drawings: coordinated, dimensioned plans; sections; elevations; wall sections - more detailed than SD but less detailed than CD.
- Outline specifications: developed in DD; identifies systems and major products without full spec section detail.
- Updated cost estimate: quantity-based or parametric; more accurate than SD estimate.
- Owner approval of DD is critical: all subsequent CD work is based on the DD design - changes after DD approval are additional services.
Study PjM on AREprep
AREprep’s PjM flashcards cover every concept on this exam with spaced repetition, and the practice exams mirror the real question formats so the actual test feels familiar.