Architectural Design Phases Explained: From Brief to Construction Drawings

If you're planning a custom home or a significant renovation, you'll hear your architect refer to project phases — Pre-Design, Schematic Design, Design Development, and Construction Drawings. These aren't arbitrary divisions. Each phase has a specific purpose, produces specific deliverables, and requires specific decisions from you as a client. Understanding the logic behind the sequence will help you know what to expect, when to push for changes, and why certain things can't happen out of order.

The Four Main Phases

Architectural projects follow a defined sequence: Pre-Design (PD), Schematic Design (SD), Design Development (DD), and Construction Drawings (CD). The naming may vary between firms and regions, but the underlying logic is consistent across residential practice.

The reason the process is structured this way is straightforward: each phase resolves a different set of questions, and those questions need to be answered in the right order. You can't develop technical details for a design that hasn't been agreed on. You can't produce accurate material lists for a design that isn't fully resolved. Skipping or compressing phases doesn't speed the project up — it creates problems downstream that take longer to fix than they would have taken to avoid.

This breakdown applies to small and medium-sized residential projects: custom homes, ADUs, and significant renovations. Larger or publicly procured projects follow an expanded process, but the foundations are the same.

Pre-Design (PD) — Building the Foundation

Pre-Design is the phase that makes everything else possible. Before any design work begins, there is a significant amount of ground to cover — and the quality of what gets gathered here directly determines the quality of what gets designed later.

The site is analyzed in detail: its orientation, topography, access, existing structures, and any physical constraints that will shape the design. The legal framework is mapped out — zoning regulations, setback requirements, permitted uses, height limits, and any permitting processes that will need to be navigated. And critically, the client's requirements are documented thoroughly: how they intend to use the space, what their priorities are, what their budget looks like, and what the project needs to achieve.

From all of this, the project brief is established. The brief is not a vague document — it is a precise definition of scope, constraints, and goals that the entire design process will be measured against. By the end of PD, there should be no ambiguity about what is being designed, for whom, under what conditions, and within what limits.

Clients sometimes underestimate this phase because nothing visible gets produced. No drawings, no 3D models. But a thorough Pre-Design phase is what prevents expensive misalignments later — discovering mid-design that the site has an easement that eliminates half the buildable area, or that the client's program doesn't fit within their budget parameters.

Schematic Design (SD) — The First Proposal

Schematic Design is where the design work begins. The brief established in PD is translated into a first proposal — initially in 2D, then developed into 3D. This is the phase most people associate with architecture: concepts, spatial layouts, massing, and the overall look and feel of the project.

The process moves deliberately from general to specific. Floor plans establish the layout and spatial relationships between rooms. Elevations begin to define how the exterior reads. A 3D model gives a clear picture of the volume and proposed character of the building before any technical commitments are made.

What SD is not is a finished design. The drawings produced at this stage are intentionally general - enough to evaluate the proposal and make informed decisions, not so detailed that changes become costly. This is the right moment to reconsider the layout, adjust the massing, or shift the design direction entirely. The further the project advances, the more expensive changes become — not because architects make them artificially costly, but because later phases involve significantly more coordinated work that has to be redone.

Feedback during SD is therefore some of the most valuable input a client can give. A well-run SD phase ends with a proposal that the client has genuinely signed off on — not one they've tolerated because they assumed things would change later.

What you receive at the end of SD:

Preliminary floor plans with general dimensions

Preliminary elevationsConceptual 3D images

3D interactive model (where applicable)

Design Development (DD) — Where the Design Gets Built

If Schematic Design answers the question of what the building will be, Design Development answers the question of how it will be built. This is the longest and most technically demanding phase of the design process, and it is where the project transitions from an agreed concept into a fully resolved technical solution.

The SD drawings serve as the starting point, but they are developed substantially. Floor plans gain precise dimensions and wall construction information. Elevations are detailed further. New drawing types are introduced that weren't part of SD: sections through the building, interior elevations showing how rooms are finished, roof framing plans, and stair details. Each of these adds a layer of technical specificity that moves the project closer to something a contractor can price and build.

This is also the phase where specialist consultants are brought into the process. Structural engineers resolve the building's structural system and produce their own drawings, which need to be coordinated with the architectural set. MEP engineers — mechanical, electrical, and plumbing — develop the building's service systems. General contractors are often consulted during DD to provide early cost feedback and flag constructability issues before the drawings are finalized. Coordinating all of this input is a significant part of what makes DD the most time-intensive phase.

By the end of DD, the project is largely defined. The design is resolved, the technical solution is in place, and the drawing set is substantially complete. The client should have a clear and accurate picture of what will be built. What remains is the final layer of precision work that makes the package complete enough to hand to a contractor.

What you receive at the end of DD:

Developed floor plans, elevations, and sections

Interior elevations

Roof framing plan

Stair details (where applicable)

Coordinated structural and specialist drawings

Construction Drawings (CD) — Ready to Build

Construction Drawings is the final design phase. The DD package is complete in terms of design decisions — CD is about translating that into a set of documentation precise and comprehensive enough for a contractor to build from without ambiguity.

Three components are added at this stage that were not part of DD, and each one serves a specific purpose in the construction process.

The bill of quantities is a complete calculation of every material used in the project — how much of it, what specification, and where it goes. This is what makes accurate cost estimation possible. Cost estimates produced earlier in the process are useful directional tools, but they involve assumptions. The bill of quantities eliminates those assumptions and is what produces a reliable final quote from a contractor. Without it, any number a contractor gives you is an educated guess.

Schedules are detailed breakdowns of specific building components: every door and window, every light fixture, every plumbing and HVAC component, every structural framing element. Each item is specified precisely — dimensions, finish, manufacturer, model where applicable. The contractor or procurement manager uses these schedules to source and purchase the right components, in the right quantities, to the right specification. Errors in schedules translate directly into errors on site.

Construction details are highly detailed drawings of specific building assemblies, drawn at large scales — 1:10, 1:5, or 1½"=1'-0" in imperial. Where the floor plans and elevations show what the building looks like, construction details show how it physically goes together: how a wall meets a roof, how a window is installed, how a stair tread is constructed. They fall into two categories: standard details, adapted from previous work on similar projects, and custom details, developed from scratch for a specific condition unique to the project. Custom details are less common but unavoidable when a project has assemblies that don't have an established precedent.

Together — finalized drawings, bill of quantities, schedules, and construction details — the CD package is what gets handed to the contractor. It is the definitive record of what is to be built.

What you receive at the end of CD:

Finalized floor plans, elevations, sections, and interior elevations

General and custom construction details

Door, window, and component schedules

Bill of quantities and material specifications

Installation plans (electrical, plumbing, HVAC)

A Note on Scope

These four phases cover the complete design process for small to medium-sized residential projects. For larger projects, public procurement, or specialized building types — healthcare, institutional, military — the process expands significantly, particularly in the stages that follow CD. The phase structure described here, however, is the foundation that all of those expanded processes build on.

If you're planning a custom residential project and want to understand how these phases would apply to your specific situation, Office Hours is a good starting point — a focused consultation before you commit to anything.