ADU Permit Drawings: What You Need to Submit

Short answer: most jurisdictions want a site plan, floor plans, elevations, sections, structural plans with calculations, and mechanical, electrical and plumbing layouts. Some also ask for an energy compliance form. Zoning rules, such as size limits and setbacks, are decided locally and checked separately.

What each drawing is for

• Site plan. Shows the property, the main house, the new unit, setbacks from property lines, and often utility connections and parking.
• Floor plans. Room layout, dimensions, door and window locations, and the use of every space.
• Elevations. What the unit looks like from each side, including heights, which planners check against zoning limits.
• Sections. A cut through the building showing floor, wall and roof construction.
• Structural plans and calculations. Foundation, framing, beams and connections, sized for the loads at your site and sealed by a licensed engineer.
• Mechanical, electrical and plumbing layouts. Heating and cooling, power, lighting, fixtures and how the unit connects to services.
• Energy compliance form, where your state or city requires one.

Do you need a structural engineer for an ADU?

Almost always for a new detached unit, and usually for a garage or basement conversion too, because you are changing the loads on the structure and creating a dwelling. The calculations are sealed by a licensed Professional Engineer.

What is checked besides the drawings

The drawings show the building meets code. Separately, the planning department checks that the unit is allowed on your lot: its size, height, setbacks and parking, and whether it can be rented. Utilities and fire access can also come into play. These rules vary widely, so check them first.

How long it takes

An ADU permit set typically takes 5 to 10 business days to prepare, depending on size and how many disciplines are involved. City plan review is separate and usually takes longer than the drawings, so plan for both.

What it costs

ADU permit drawings start at $2,200, with a fixed scope and price confirmed before work begins. A typical set uses structural, MEP and sometimes civil work, and you can see every service on the pricing page. For the full list of what is included, see our ADU permit drawings page.

Where to start

Send a sketch, photos of the site and the size you have in mind. We tell you what your building department is likely to ask for, and give you a fixed price before you pay anything. If you are planning to turn an existing garage into the unit, read garage conversion permit requirements first.

This article is general information. Local zoning and building rules differ, and your planning and building departments have the final word. Checked October 2026.