Essential Drawings for ADU Permitting

Nadeem F
Oct 28
4 min read

Accessory Dwelling Units (ADUs) are self-contained secondary living spaces located on the same property as a single-family home. They can take the form of backyard cottages, garage conversions, or basement apartments, and have become increasingly popular as homeowners seek flexible housing options, rental income, and solutions to local housing shortages. As more cities and counties embrace ADUs, ensuring your project starts off right—with detailed, accurate drawings for permitting—has never been more important. In this guide, you’ll learn about the specific types of drawings required for ADU permitting, tips for successful preparation, and access to a practical checklist to help homeowners stay organized throughout the process.

Before breaking ground on your ADU, you must first secure permits from your local building authority—a critical step to ensure code compliance and safety. The permitting process for ADUs generally includes submitting a comprehensive set of plans, undergoing reviews for zoning and building compliance, and, in some cases, responding to comments or requests for revisions. While requirements may vary, most jurisdictions will examine your drawings for adherence to setbacks, lot coverage, minimum and maximum size limits, parking requirements, and other zoning or code-related stipulations. Always check with your city or county’s planning department for exact requirements, as regulations can differ widely by location.

Essential Drawings Required for ADU Permitting

A. Site Plan

A site plan is a scaled drawing showing the entire property and the location of all existing and proposed structures. This includes property lines, setbacks (distance from property boundaries to buildings), driveways, walkways, landscaping, utility connections, and easements. It’s essential for demonstrating how your ADU fits within the broader context of your lot and complies with local zoning and building codes.

B. Floor Plans

Floor plans provide a detailed, top-down view of the proposed layout, depicting walls, rooms, doors, windows, fixtures, and dimensions. Precise floor plans help reviewers verify aspects like minimum room sizes, accessibility, and emergency egress, streamlining the approval process.

C. Elevations

Elevation drawings visually represent each exterior side of your ADU, including material notes, rooflines, window and door placements, and maximum height. These help permit officials confirm that your ADU’s design meets architectural and height requirements, fits the local neighborhood context, and adheres to design review standards where applicable.

D. Structural Drawings

In many cases, especially for new builds or significant structural changes, you’ll need a set of structural drawings. These plans provide details on foundations, framing, connections, and materials, ensuring your ADU is built safely and complies with the most current building codes. Structural drawings may require a licensed engineer’s or architect’s stamp.

E. Mechanical, Electrical & Plumbing (MEP) Plans

MEP plans map out key systems: heating and cooling (mechanical), electrical wiring/outlets/fixtures, and plumbing lines/fixtures. The level of detail required—such as showing load calculations, electrical circuits, or venting—depends on local rules and the scope of your project. Some jurisdictions may require these to be completed by licensed professionals.

F. Additional Plans

Some projects require supplementary documentation—especially in certain states like California. Examples include energy calculation reports or Title 24 compliance documentation to demonstrate energy efficiency, landscape plans showing new or modified plantings, and erosion control plans if major site work is involved. Check with your local planning staff for all special requirements before submission.

How to Prepare and Organize Your Drawings

For the smoothest permitting process, consider partnering with professionals—qualified architects, designers, or engineers—who are familiar with ADU regulations in your area. Use digital drawing formats (often PDF or CAD) as many planning departments now accept or require electronic submissions. Ensure clarity and consistency: all pages should be scaled, labeled with north arrows/legends where appropriate, and use matching design information throughout. Common pitfalls that can delay approval include incomplete drawings, inconsistent measurements, missing details (such as unclear demolition areas), or lack of required stamps or signatures. Double-check your local submittal checklist before filing to prevent unnecessary delays.

Step-by-Step Checklist

Confirm local ADU requirements/zoning code
Obtain a property survey or site base map
Draft or hire professionals for:
Site Plan
Floor Plans (existing and proposed)
Building Elevations (all sides)
Structural Drawings (if required)
MEP Plans (Mechanical, Electrical, Plumbing)
Additional documents (energy reports, landscape plans, etc.)
Ensure all drawings are scaled, clearly labeled, and consistent
Gather required signatures/stamps (architect, engineer, homeowner)
Review and fill out your jurisdiction’s permit application forms
Assemble drawings and forms in digital format (PDF or as specified)
Submit complete application to the city/county building department
Monitor your application status and respond promptly to any city review comments

Complete, accurate drawings are at the heart of a successful ADU permitting process—they help avoid costly mistakes, keep your project moving, and set you up for code-compliant construction. Begin with a thorough understanding of local requirements, work with qualified professionals when needed, and use checklists to stay organized. For an even smoother start, download a sample ADU checklist/template or consult with your city’s building department for guidance tailored to your location. Your well-prepared plans are the foundation of a great new living space!