SD, DD, CD (Construction Design Stages) — Full Guide

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SD, DD, CD (Construction Design Stages) — Full Guide

Understand what each stage means, what documents you should expect, and what level of detail is included.

SD = Schematic Design DD = Design Development CD = Construction Documents

SD — Schematic Design

Early stage: concept + overall layout (not construction-ready).

  • Main goal
    Confirm the design idea with the client (big picture).
  • Detail level
    Low — basic sizes and arrangement.
  • Typical outputs
    Basic floor plan, massing, simple elevations/sections, rough budget.

DD — Design Development

Middle stage: develop SD into a workable, coordinated design.

  • Main goal
    Fix dimensions and systems; coordinate architecture + structure + MEP.
  • Detail level
    Medium — more accurate and closer to real construction.
  • Typical outputs
    More detailed plans/sections, structural & MEP concepts, material/finish selections, better cost estimate.

CD — Construction Documents

Final stage: complete drawings & specs used for permits, bidding, and construction.

  • Main goal
    Produce final instructions for the construction team.
  • Detail level
    High — final dimensions, final reinforcement details, final schedules.
  • Typical outputs
    Full architectural set + structural set + MEP set + specs (and sometimes BOQ/QTO).
SD — What it includes / excludes
Includes
  • Basic floor plan: room arrangement + approximate sizes
  • Building massing: overall shape, height, volume
  • General structure concept: grid idea, beam/slab concept (very general)
  • Basic exterior look: simple façade / roof idea
  • Preliminary (rough) cost estimate
Does NOT include
  • Rebar detailing / shop drawing level
  • Final dimensions everywhere
  • Fully coordinated MEP drawings
DD — What it includes
  • Plans become more accurate: wall thickness, openings, key dimensions
  • Elevations and sections become clearer: heights, windows/doors, roof shape
  • Structural system becomes real: column positions fixed, beam layout fixed, slab thickness proposed
  • MEP concept planning: plumbing/electrical routes and coordination start
  • Cost estimate becomes more accurate (still not final)
DD is like: “We confirm the design is correct and workable before final drawings.”
CD — What it includes
Typical drawing sets
  • Architectural: detailed plans, sections, elevations, schedules (doors/windows), details
  • Structural: foundation, columns, beams, slabs reinforcement details, schedules
  • MEP: electrical, plumbing, drainage, water supply (and HVAC if used)
  • Specifications: materials, standards, methods (e.g., waterproofing)
  • BOQ/QTO (sometimes): for pricing and tender
CD is like: “This is the instruction book for the construction team.”
Stage Meaning Detail Level Used for
SD Schematic Design Low Concept approval and overall layout agreement
DD Design Development Medium Refine design, coordinate systems, improve cost accuracy
CD Construction Documents High Permits + tender/bidding + construction on site

Simple Example (House Project)

Same project, different level of detail at each stage.

  • SD: “2-storey house, 3 bedrooms, living room, kitchen, garage.”
  • DD: “Bedroom 3.5m × 4.0m, L-shape stair, roof slope 30°, window locations confirmed.”
  • CD: “Beam 200×450, stirrup DB8 @100, slab 120mm, waterproofing details, schedules included.”
Tip: If you see names like “SD Plan”, “DD Model”, or “CD Building” in SketchUp Outliner, it usually means the model is organized by these project phases.
Want the next stages too? (Tender/Bidding and CA = Construction Administration) — tell me and I’ll add them to this Smart-Book.
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