Level of Detail by Project Phase: SD, DD, and CD Drawing Requirements and Content Progression

How architectural documentation evolves across Schematic Design, Design Development, and Construction Documents, including the expected drawing content, level of geometric definition, coordination requirements, and deliverables at each phase, along with BIM Level of Development (LOD) frameworks that define element reliability and progression from conceptual massing to construction-ready detail.

ARE · Project Development & Documentation

Overview

Every architectural project moves through distinct documentation phases, and the drawings produced at each stage serve different purposes. Schematic Design (SD) drawings communicate broad design intent through massing, spatial relationships, and preliminary material concepts. Design Development (DD) drawings lock down systems, dimensions, and material selections so that the design can be accurately estimated and coordinated. Construction Documents (CDs) carry the full legal and technical weight of the contract, specifying exact assemblies, details, and instructions a contractor needs to build.

Understanding what belongs in each phase is not just an organizational preference. Providing too much detail too early wastes effort on elements that will change; providing too little detail too late creates coordination gaps, cost overruns, and liability exposure. The BIMForum Level of Development (LOD) Specification gives teams a shared vocabulary for describing how far each model element has been developed, from LOD 100 placeholders through LOD 400 fabrication-ready geometry.

On the PDD exam, you will be asked to evaluate whether documentation is appropriate for a given project phase, decide when drawings need updating as requirements change, and judge whether the level of detail matches the project's delivery method and complexity. This topic sits at the heart of Objective 2.1, which tests your ability to determine a drawing and documentation approach that aligns with project conditions.

Essential

The progression from Schematic Design through Construction Documents follows a logic that mirrors how design decisions solidify. Each phase adds precision, coordination, and contractual weight to the documentation set. Getting the level of detail right at each stage affects project cost, schedule, constructability, and the architect's liability. ## Schematic Design: Establishing Design Intent SD drawings answer the question: what is this project going to be? At this stage, documentation shows building massing, total spatial organization, primary circulation, and the general structural and mechanical approach. Floor plans are typically drawn at small scales (1/16" = 1'-0" or 1/8" = 1'-0") and show room layouts, major openings, and approximate dimensions. Elevations convey the building's character and proportional relationships. Building sections show floor-to-floor heights and the general relationship between structure, envelope, and occupied spaces. Drawings at SD level should not include construction details, partition types, or finish selections.

Professional

Consider a mid-rise mixed-use project under CM-at-risk delivery. The owner wants to break ground before the full CD set is finished, starting with foundations and structural steel while the interior fit-out is still in DD. The architect faces a documentation sequencing problem: the early release structural package needs CD-level precision (fully detailed connections, reinforcing schedules, embed locations), while the architectural interiors package only needs DD-level information (partition types identified, ceiling heights confirmed, but individual outlet locations and finish transitions still under development). This situation demands evaluating each building system's documentation needs independently. The structural engineer's BIM elements for the early package should reach LOD 350, showing interfaces with the architectural slab edges and mechanical penetrations. Meanwhile, the interior partition model might still sit at LOD 200, with generic wall types placed in approximate locations.

TLDR

SD shows design intent: massing, spatial layout, general systems. No construction details. Model elements at LOD 100-200.
DD locks down dimensions, systems, and material selections. Schedules appear. Model elements reach LOD 200-300. Coordination begins.
CDs provide full contractual documentation: every detail, every dimension, every specification cross-reference. Critical elements reach LOD 350 for construction coordination.
LOD 350 adds interface modeling (penetrations, clearances, connections) and typically requires craft knowledge beyond what designers produce alone.
LOD requirements are cumulative from 100 through 400. LOD 500 is separate and describes existing/as-built conditions.
Level of Development measures element reliability. Level of Detail measures visual information. They are not the same concept.
Different elements within the same model can sit at different LOD levels at any given phase.
Delivery method changes the expected documentation at each milestone. Fast-track and design-build compress or rearrange the traditional SD-DD-CD sequence.

ELI5

Think of architectural drawings like writing a book. The first draft (Schematic Design) is a rough outline. You know the main characters, the setting, and the plot, but the dialogue and details are still fuzzy. Nobody would try to film a movie from just an outline. The second draft (Design Development) fills in the chapters. Now you have actual scenes with specific details. Characters have names, locations have descriptions, and the storyline holds together. You could hand this to someone and they would understand the story, but they would still need more specifics to bring it to life. The final manuscript (Construction Documents) is the complete, polished version. Every word is chosen. Every scene is fully described. This is what the publisher (contractor) uses to actually produce the finished product (building). If something is missing or contradicts another part of the manuscript, the production stalls.

AREProject Development & Documentation

Level of Detail by Project Phase: SD, DD, and CD Drawing Requirements and Content Progression

2 min read215 words

Drawing Content Grows with Each Phase

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