Design development
The middle design phase, where mechanical, electrical, plumbing, and structural details turn a concept into a buildable plan.
Design development is the middle phase of architectural design: after the concept is approved in schematic design, and before construction documents are drawn. In this phase the architect turns the initial sketches into mechanical, electrical, plumbing, structural, and architectural detail, so the board is reviewing a real, buildable plan, not just a concept.
Where this phase sits in the sequence
A capital project's design work runs through three phases in order: schematic design, design development, and construction documents. Design development is the middle one. It does not start from a blank page, it takes what came out of schematic design and works it further.
Design development "use[s] the initial design documents from the schematic phase and take[s] them one step further" and "lays out mechanical, electrical, plumbing, structural, and architectural details."
Source: Defining the Architect's Basic Services, American Institute of Architects
Nothing here is final pricing detail yet. That comes next, in construction documents, when the architect adds specifications for construction details and materials that a contractor can actually bid against.
What changes across the three phases
It helps to see all three phases side by side, because boards often can't tell which drawings they're looking at.
| Phase | What the board is reviewing |
|---|---|
| Schematic design | Project goals and requirements the architect worked out with the board; a concept, not a plan |
| Design development | Mechanical, electrical, plumbing, structural, and architectural detail added to that concept |
| Construction documents | Drawings with greater detail plus specifications for construction details and materials, ready for bidding |
If a drawing set the board is reviewing already shows fixture models and material call outs, that's construction documents, not design development. If it's still floor plans with rough system layouts, that's design development. Knowing which one you're holding tells you how firm the plan actually is.
Why the board's review here matters
Design development is where the structural and mechanical systems get worked out in detail. A change the board asks for during this phase, a different roof structure, a relocated mechanical room, means the architect reworks that detail before moving on. It is normal, expected work at this stage.
A change asked for later, after the project moves into a signed construction contract, is a different animal. It becomes a change order, a documented, agreed change to the contract's scope, price, or schedule, not a design revision.
That's the practical reason to read design development drawings carefully before signing off: the detail decided here becomes the basis for the specifications the next phase writes and, eventually, for what the specifications and bid documents hold the contractor to.
Check yourself
Answer before you read the explanation, recalling it is what makes it stick.
The board just approved a simple concept sketch and rough project goals. Which phase happens next?
Partway through design development, the board asks the architect to switch from a flat roof to a pitched roof. What does that request actually trigger?
A board member finds drawings labeled design development and asks whether they show exact plumbing fixture models and material call outs for bidding out the job.
Sources
- Defining the Architect's Basic Services, American Institute of Architects
- Change Orders, Associated General Contractors of America
Capital Projects
Next, see how design development's detail turns into the specifications a contractor actually bids on.
Whether design development requires a separate board vote, and which contract terms govern the architect's fee and scope at this stage, vary by association bylaws and by the design contract signed.