How much do ADU plans cost?

When people say “ADU plans,” they usually mean the drawings and documents needed to describe the accessory dwelling unit for design review and permit submission. That can include floor plans, elevations, sections, site plans, and sometimes coordination with other consultants.

The cost is not just for drawings. It also reflects time spent on meetings, code research, revisions, and making the set more complete for your city or county. Rules vary by state and city, so the amount of work can change a lot from one project to another.

Studio Northing is not an architecture firm and does not provide architectural, engineering, or legal advice. We help you find and match with a licensed architect who can discuss your project and explain their fee structure.

Architects and design professionals often price ADU plans in one of three ways: a fixed fee, an hourly fee, or as a percentage of construction cost. For smaller, straightforward ADUs, a fixed fee is common because it makes the scope easier to understand.

As a general market pattern, plan fees for residential design services may fall somewhere around a few thousand dollars for very simple work and can rise much higher for custom, larger, or complicated projects. A percentage-based fee is sometimes used for broader architectural services, but it depends on the project scope and local market.

Ask exactly what is included. Some quotes cover only basic permit drawings. Others include more design development, revisions, consultant coordination, or help responding to reviewer comments.

Several things can increase the effort and price of ADU plans. These include tight sites, sloped lots, historic districts, coastal or fire zones, utility constraints, and zoning issues like setbacks, lot coverage, or floor area ratio (FAR), which means how much building area is allowed on a lot.

Complex projects also cost more when the ADU must fit around an existing house, garage, or accessory structure. If you need structural changes, energy code work, or mechanical, electrical, and plumbing coordination, that can add time and cost.

A simple interior conversion usually needs less work than a detached new ADU. That said, every site is different, so a “simple” project in one city may still require a lot of revisions in another.

Do not compare price alone. Compare scope, deliverables, revision limits, and whether the architect has experience with ADUs in your city or county. The cheapest option is not always the least expensive once extra revisions or consultant fees are added.

Good questions to ask:

• What drawings are included?
• How many revision rounds are included?
• Are site visits, meetings, or permit responses included?
• Who coordinates with structural or MEP consultants if needed?
• What is excluded from the fee?

Also verify the architect’s state license. Licensure rules vary by state, and you should confirm the professional is properly licensed where your project is located.

If you are early in the process, we can help you understand what kind of architect you need and connect you with a licensed architect who works on ADUs. That can save time if you do not know where to start or you are worried about explaining your project in English.

We are free for the reader. We help you find a licensed architect, but we do not design the project, stamp plans, or guarantee any permit outcome. Participating licensed architects pay a flat fee to be matched with projects; that does not change your cost or our advice.

If you want broader background first, browse our guides or review our services. When you are ready, you can get matched.