SD, DD, and CD Sets: What Actually Changes Between the Three Drawing Phases

The real problem: "which phase are we in" decides what you're allowed to draw

Most rework on a project doesn't come from bad drafting — it comes from drawing CD-level detail during SD, or shipping an SD-level set when the client thinks they're approving construction documents. A junior who dimensions a wall to the eighth-inch before the structural grid is locked has just produced a drawing that will be deleted. A PM who lets a client "approve" a schematic plan as final invites scope creep the moment systems land and the layout shifts. Phase language exists to prevent exactly this: it tells everyone how much certainty a drawing carries, how much it can still move, and what decision the set is actually asking the team or client to make. Get the phase wrong and you either burn billable hours on premature precision or you set an expectation the next phase will break.

• SD = big moves, still soft, everything subject to change
• DD = systems and materials locked, geometry firming, consultants engaged
• CD = fully coordinated and specified, drawn to build from

Schematic Design (SD): the concept, the massing, and a Rough Order of Magnitude

SD answers the question "what is this building, roughly?" The team establishes the design concept, overall massing and form, building organization, approximate room sizes and adjacencies, and the primary circulation and site relationships. Drawings are diagrammatic and dimensionally loose — single-line plans, study sections, massing views, and area takeoffs sufficient to confirm program fit and a Rough Order of Magnitude (ROM) cost and area. Nothing is detailed; the point is to align the client, the program, and the budget on the big idea before anyone invests in resolution. The deliverable is a set the client can react to conceptually, not build from. The gate at the end of SD is a client (and often authority-having-jurisdiction pre-application) sign-off on direction and budget envelope — approval to proceed into systems.

• Decides: concept, massing, program fit, adjacencies, big site moves
• Delivers: single-line plans, study sections, area + ROM cost estimate
• Sign-off: client approves direction and budget range to advance

Design Development (DD): systems lock, materials get selected, dimensions firm up

DD answers "how does it actually go together?" This is where the soft concept becomes a coordinated design. Structural, MEP, and other consultants are engaged in earnest; the structural grid is set, mechanical strategy and major equipment are sized and located, and the layout stops moving because real systems now constrain it. Materials and finishes are selected (not just imagined), key wall types and assemblies are established, and plans, sections, and elevations are dimensioned and refined to near-final geometry. The estimate tightens from ROM to a more reliable design-development cost, and value-engineering decisions happen here while they're still cheap to make. The DD gate is the client signing off on a resolved design — materials, systems, and layout — so that the team can commit to full documentation without expecting the design itself to change.

• Decides: structural/MEP systems, material and finish selections, firmed dimensions
• Delivers: coordinated plans/sections/elevations, wall types, refined DD estimate
• Sign-off: client approves the resolved design and material direction before CDs

Construction Documents (CD): fully coordinated, dimensioned, specified, buildable

CDs answer "build exactly this." The set is the legal and technical instrument a contractor prices and constructs from: complete dimensioned plans, sections, elevations, enlarged plans, wall sections, details, schedules (door, window, finish, equipment), and a coordinated specification — typically organized to CSI MasterFormat. Every consultant's drawings are cross-coordinated; clashes that were tolerable as "figure it out in CD" during DD must now be resolved. Nothing is left to interpretation that affects cost, code compliance, or constructability. CDs are also the permit set submitted for the building-permit review and the basis of the construction contract. The CD gate is the architect's (and engineers') professional seal and the owner's authorization to issue for permit and bid — the point where the drawings carry liability and become contractually binding.

• Decides: every dimension, detail, schedule, and specification needed to build
• Delivers: fully coordinated permit/bid set + CSI-organized specifications
• Sign-off: architect/engineer seal; owner authorizes issue for permit and bid

One plan, three fidelities — and roughly how the fee splits

The cleanest way to feel the difference is to picture a single floor plan drawn three times. In SD it's a single-line diagram with bubble rooms and approximate dimensions. In DD the same plan gains real wall thicknesses, a structural grid, located fixtures and equipment, door swings, and dimension strings. In CD it carries full dimensioning, wall-type tags, detail callouts, schedule keys, and references to specs — the line that was conceptual in SD is now a specified, coordinated assembly. On fee, design-phase effort commonly splits roughly SD ~15%, DD ~20%, CD ~40% of basic services, with the remainder in bidding/negotiation and construction administration. Treat these as planning ratios, not contract terms — actual splits vary by firm, contract (e.g., AIA B101 phase percentages are negotiated per project), and project type. The pattern that holds everywhere: documentation effort escalates sharply as you move toward CD, because that's where every decision finally has to be drawn.

• SD plan: single-line, bubble rooms, approximate dimensions
• DD plan: true wall thicknesses, structural grid, located equipment, dimension strings
• CD plan: full dimensioning, wall-type tags, detail/spec callouts, schedule keys
• Indicative fee split: SD ~15% / DD ~20% / CD ~40% (negotiated, varies by contract)