• Daniel Saloner

Your Guide to ADU Permitting

So, you’ve made the exciting decision to build an Accessory Dwelling Unit (ADU) and you’ve just finished up the design process. What comes next?


We know -- not the most exciting part of building your ADU -- but that’s why Building Buddy is here to help. There are going to be multiple steps you need to take before your permit to build an ADU is issued. If you know anyone who has built an ADU or read up on the topic before finding us here at Building Buddy, you have likely heard quite a bit about city fees and permit requirements. Those can often be confusing or difficult to sift through and we are here to help you navigate this unfamiliar process.

Here is a brief overview of the timeline for plan checks & permits:

Plan Check Fees

After the design and planning phase of your new build, you will have construction drawings in hand. Construction documents are the written and graphic documents that hold the instructions to building your ADU. Once these documents are completed, you will need to submit them to the city for review. A quick note to add, if your property is in a coastal overlay zone, your construction drawings will need to first go through the coastal committee before being submitted to plan check with the city. Then, once you have submitted to the city, you will need to pay a submittal fee.

Revision Period

After submitting your plan check, you typically will hear back from the city within 2 weeks; however, during COVID, the estimated time can be as long as 4-8 weeks. When you do hear back, you will receive revisions from the city to make corrections and go through clearances with all utility departments: power, water, gas, fire department, sanitation, etc. During this phase, each department will sign and approve the project and will give revisions as needed.

Permit Fees

After you have made revisions required by all utility departments and received approval from those same utilities, you are ready to re-submit the plans for your ADU. Once submitted, you will have a final plan check review meeting with the city engineer, who will either approve the ADU or ask for further revisions. If the project is approved with no further adjustments, you will be issued a building permit. Once you have a building permit, it is time to pull the construction permit and move forward with construction .

Overall Cost of Permitting

Permit fees can vary by city and municipality as well as the size of your proposed ADU. A garage conversion of 300 square feet will cost less in permit fees than a detached 1,200 square foot ADU. However, regardless of who builds the ADU or how it is built, city permit fees typically range from $6,500 to $14,500 based on size and location. A good measure to use is planning for $10-12/sqft in fees. Here is a rough breakdown of fees for your project:

  • Planning Review Fees: $2,000-4,000

  • Building Permit Fees: $1,000-4,500

  • Impact Fees: $1,500-3,000 (not applicable to ADU’s under 750 sqft)

  • School Fees: $1,000-2,500 ($3-4/sqft) (not applicable to ADU’s under 500 sqft)

  • Water/Sewer Fees: $1,00-2,500

  • Total: $5,000-14,500

This may all sound like a lot -- both in complexity and cost -- but Building Buddy is here to help guide you through the process and ensure permitting goes as efficiently as possible so you can get to the good part: building your ADU.