The CD set is one object, many views.
Who This Matters To (And Why)
Critical: Architect,GC,City. These parties make or lose money directly based on this thesis.
Important: Engineer,Developer,Inspector. These parties execute decisions shaped by this thesis.
Context: Banker,Investor,Interior Design. These parties need to understand it to avoid friction.
Highest typology impact: Multifamily,Office,Hotel,Industrial. Lower impact: Retail,Mixed Use.
The CD set is one building model expressed as many views. Plans, sections, elevations, schedules are all the same object.
How It Shapes Development
The CD set is one object with many views because construction documents are not a collection of independent drawings — they are a set of coordinated projections of a single building model. The floor plan is a horizontal section of the model. The elevation is a vertical projection. The section is a vertical cut. The detail is a zoomed region. The schedule is a data query. All of these views describe the same object. When the object changes, all views must change consistently. In traditional 2D CAD documentation, maintaining that consistency is manual work. In a model-based workflow, it is automatic.
Coordination failures between views are the most expensive documentation errors. A dimension on the floor plan that contradicts the dimension on the reflected ceiling plan. A window shown on the elevation that doesn't appear in the window schedule. A door shown on the plan that has no schedule entry. Each of these represents a divergence between two views of the same object — a sign that the drawings were maintained as separate documents rather than derived from a single model. The contractor who encounters the conflict must issue an RFI. The RFI requires design team response. The response may require field work to be redone. The cost of the coordination failure accumulates at each step.
Sheet organization in a CD set is a navigation system for the object's views. The G series covers general project information. The A series covers architectural views: plans, elevations, sections, details, schedules. The S series covers structural. M, P, E cover mechanical, plumbing, electrical. Each series is a subset of views of the same building object, filtered by discipline. A contractor reading the documents navigates between views to reconstruct the three-dimensional object from its projections. Poorly organized documents make navigation difficult. Well-organized documents make the object legible from any view.
Issued-for-construction drawings are a snapshot of the object model at a specific point in time. When the model changes after IFC issue — through RFIs, ASIs, or change orders — the drawings no longer accurately represent the object as built. As-built documentation is the effort to resynchronize the drawing set with the actual constructed object. It is expensive because 2D drawings require manual updating. A model-based workflow reduces as-built cost by maintaining a live model that can be queried at any time for current object state. The as-built set becomes a final query against the model rather than a manual redlining exercise.