Boise ADU Approval Process: A Complete Guide [2024]

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It’s no secret that the number of ADUs and ADU permit applications in Boise have exploded in recent years. In fact in the first three months of 2024 there were 38 new ADU permit applications submitted in Boise versus 48 ADU permit applications submitted in all of 2023. [Source: boisedev.com]. If you are interested in the Boise ADU approval process you are most likely already aware of the benefits of building an ADU in Boise and may already have an ADU floor plan you’d like to build on your property, but how do you go about getting approval for your ADU?


As a custom home builder in Boise, we’ve gone through the Boise ADU approval process with our clients many times, both those looking to add an ADU on their property and those building both a main home and ADU on their land at the same time. As such, we know what the Boise ADU approval process entails and we’ll walk you through the steps you need to take to go through the process and start building your ADU in Boise.

Boise ADU Approval Process Overview

The Boise ADU approval process is a four step process. This process follows the general City of Boise planning process and is designed with efficiency in mind to make sure that you don’t get too far along without knowing if there are any potential issues with your ADU application. In the city’s process, the first two steps are pre-reviews before you submit your ADU application and then it is finally reviewed and approved as the final step.

Boise ADU Requirements

Before you jump to the Boise ADU approval process, you’ll want to review the Boise ADU requirements to make sure that the ADU you’d like to build meets these requirements. Below are the key requirements for building a new ADU in the city of Boise as of July 2024. You can also view the most up-to-date Boise ADU laws in the Boise City Code.

  1. An ADU cannot be larger than 900 square feet or the total floor area of the primary building, whichever is smaller. 
  2. ADUs in Boise cannot have more than 2 bedrooms. 
  3. Only one ADU is allowed on each lot or parcel.
  4. The ADU must meet all of the dimensional requirements of the underlying zoning district as well as the provisions of the International Building Code. 
  5. The primary dwelling unit and the ADU shall be designed to portray the form of a single-family dwelling.
  6. The design of the ADU must be compatible with the neighborhood.
  7. A Zoning Certificate is required for approval of an ADU
  8. Impact fees for accessory dwelling units shall be assessed at a portion of the standard single family residential fee as determined by the applicable agency. 
  9. There can only be one entrance to the ADU located on the front building elevation of the house unless multiple entrances are already in existence.

Now that you understand the Boise ADU requirements, you can move on to get your ADU project approved.

Step By Step Boise ADU Approval Process

Step 1: Early Assistance

The first step in the Boise ADU approval process is a program called Early Assistance, which allows you to talk with someone in the city planning department about your project before you spend time and money developing your site plans. The goal of Early Assistance is to help make the process smoother and more efficient by helping you understand if the general concept of your plan is viable before you continue with planning and permitting. 

To complete this step, all you need to do is schedule a time to talk with someone about your project. At this stage you don’t need any specific information, just the general idea of your project and the project location will suffice. You can visit the City of Boise website to learn more & schedule your Early Assistance appointment.

Step 2: Concept Review

Following Early Assistance, the next step in the Boise ADU approval process is to create a project profile in the Permitting and Licensing system before step two – Concept Review.

Create A Planning Case For Concept Review

  1. The process for starting your Planning Case is to create a Planning Project on the Boise Permitting and Licensing website. To do so, you will first create a login, then at the top of the page hit apply. 
  2. Then select ‘Planning’. Continue to accept the disclaimers and follow the prompts.
  3. Once the planning case has been created, you will see a landing page with a PLN23-XXXXX number. This is your planning project number. Your request will then enter the queue and await assignment to a Planner on the Development Services Team for Concept Review.

When you are creating your Planning Case, you’ll need to upload a project description and a site plan. The project description you submit for your Concept Review needs to include the following at a minimum:

  • The address or addresses of the parcel
  • Project vision including the design intent and philosophy of the project and how it will interact with the surrounding community
  • The number and type of unit(s)
  • Access and parking information

You’ll also need to submit a site plan and you may also choose to provide additional information relevant to your project at this stage. The more detailed you are, the better the information the city has to review and determine the viability of your ADU project.

Once your project description and site plans are received, the city planning department will do a high-level review of your project to ensure it is an allowed use in the zone and check for any other entitlements that may be required, such as a floodplain entitlement.

Example of rough site plans to represent the concept review step of the Boise ADU approval process.

This Concept Review is the part of the pre-review process in which the city determines what type of application is needed for your ADU project, either administrative or hearing-level. Almost all ADU applications will be administrative level, unless there are other considerations, such as construction in the historic district. 

During the Concept Review portion of the Boise ADU approval process, you will meet with the city planning department to review your project. The Concept Review meeting topics can include a review of the site plan, any potential roadblocks or necessary changes, and alignment with the zoning code. You will also find out the next step for your project.

If the city has any questions about your Planning Case, they will reach out to you before moving you on to the next step, which is creating the application for you after determining that your ADU project will work. For more information on the Concept Review, see the Concept Review information on the City of Boise website.

Step 3: ADU Application

Once you’ve made it through the Concept Review, the next step in the Boise ADU approval process is the formal planning application. The application will be started in your Permitting and Licensing account following your Concept Review. 

Most likely your ADU project application requires an administrative review, meaning your next step is to submit your application. Here we will stick to the instructions for the administrative application, which is the most common Boise ADU approval process. If there are other steps required prior to filing your application, the city will alert you to the next steps following your Concept Review and you should proceed with those next steps.

Steps to Submit Your ADU Application

To submit your Boise ADU application, you can follow the steps below. Here is the full checklist of items needed to complete your application.

Screenshot of the City of Boise permitting and licensing website login page - 2024

City of Boise Permitting & Licensing Website

  • Login to the Permitting and Licensing site.
  • Locate the “Home” drop-down menu at the top left of your screen.
  • Click on “My Records” from the drop-down menu.
  • Review your application under the “Planning” header by clicking “Complete this form“.
  • Review each section of the application by clicking on the link “Click here to review and edit“. Make sure all required fields designated with a red asterisk are populated. It is very important to make sure all required fields are complete and you have provided any additional information.
  • Submit your application.

If any additional information is needed for you to complete your application, you will be notified via email about the information needed.

This application stage is also when you’ll be submitting your application fee. Once you’ve submitted all information and paid your fee, your application will move to the final step in the Boise ADU approval process – review and approval.

Step 4: ADU Application Review and Approval

At this stage of the Boise ADU approval process, your portion of the application is already complete and you’ll be waiting for the city planning team to review and approve your application for a Zoning Certificate. The time frame for approval can vary, but once your project is reviewed and approved, you will receive a notification of either Approved, Approved with Conditions, or Denied.

If your application decision is Approved, you can continue with your ADU project. If Approved with Conditions, you’ll need to make the necessary changes to meet the conditions in your approval before getting started. If your application is denied, you can either appeal the decision or make adjustments to your application and resubmit the application for review.

That’s it! Once you’ve gone through this four step Boise ADU approval process, you will be ready to start building your ADU. If you have questions about building an ADU in Boise or are looking for an ADU builder, contact us for a free consultation

Boise ADU Approval Process FAQs

What is the cost to submit an ADU application in Boise?

You can view the current City of Boise application fee schedule for the latest ADU application costs.

Where can I find the Boise ADU approval process information on the city website? 

At this time the City of Boise does not have an ADU specific approval process page; however, you can find all of the general ADU planning process information on the city’s Planning Process Overview page as well as information on how to get in contact with city planning if you need additional assistance or information.