The recent popularity of ADUs in the city of Boise, has trickled out to surrounding counties and towns, including nearby Canyon County and cities like Nampa and Caldwell. Whether you are considering building an ADU to rent out for an additional income stream or you are building a space to accommodate multigenerational living, you’ll need to go through the Canyon County ADU approval process before you start building and can take advantage of all the benefits of building an ADU.
As a custom home builder serving Canyon County and Treasure Valley, we’ve helped many clients build ADUs on their land as an addition to their primary dwelling unit and we know the ADU approval process isn’t always straightforward. We’ve created this guide covering the Canyon County ADU approval process to help make the process a little easier and minimize any permit-related issues that may arise during the building process.
Canyon County ADU Approval Process Overview
The Canyon County ADU approval process can be broken down into four steps. Similar to the Boise ADU approval process, these steps are designed with efficiency in mind. The goal is to ensure that you don’t get too far along in the process before you find out about any potential issues with your planned ADU.
Canyon County ADU Requirements
Before you start the Canyon County ADU approval process, it’s important to know the general ADU regulations in Canyon County. While there are no county-specific regulations, you’ll need to follow any statewide ADU regulations and the usual residential building regulations, zoning, and ordinances for the county.
In addition, all ADUs must follow all local municipality ADU regulations. Where the rules are different, you’ll need to default to the more strict version.
Below you can find quick information about ADUs in two of Canyon County’s largest municipalities. For additional information on Canyon County building requirements, visit the Canyon County Building Department.
Caldwell ADU Regulations
City of Caldwell ADU Regulations
- Maximum Size: 700 square feet
- Only 1 Bedroom ADUs Allowed
- Owner must live in one of the structures on the property
Nampa ADU Regulations
City of Nampa ADU Permit & Regulations
- Maximum Size: 500 square feet
- Only 1 Bedroom ADUs Allowed
- Only 1 ADU allowed per property
Step By Step Canyon County ADU Approval Process
Step 1: Check Zoning Restrictions
For any building project, whether it is a custom home or an ADU, the best place to start is by checking local planning and zoning ordinances to ensure there are no restrictions that would prevent you from building on your land.
In Boise, the city offers assistance with this step through its Early Assistance program; however, in Canyon County, Idaho there is no specific program designated for the Canyon County ADU approval process.
To check the zoning regulations and restrictions for your land, you can find information on the Canyon County Planning & Zoning Department website. Here you’ll also find subdivision plats, CC&R’s, and information on county codes and ordinances.
If you are building on land in Nampa, you can find information on the City of Nampa’s Planning and Zoning Department website.
This first step in the Canyon County ADU approval process is critical to ensure you don’t waste time, energy, and resources designing and planning for an ADU that you won’t actually be able to build.
Step 2: Create Your ADU Building Plans
Once you’ve confirmed that your property is zoned to build an ADU, you can move on to the next step in the Canyon County ADU approval process, which is designing your ADU and creating a floor plan & site plans to submit with your building permit.
If you haven’t already selected an ADU builder, this is when you’ll want to do so as your builder will be involved in creating your site plans, which you’ll need to submit with your building permit application. This applies wherever you are building in Canyon County.
At Pathway Builders, we have a number of ADU plans, ready to customize and build on your land. Whether you are looking for an ADU with an attached garage or a standalone ADU floor plan, you can view all of our ADU plans and find one that fits your needs. To find out how much an ADU costs to build on your land, you can use our instant quote tool and get an estimate today.ation relevant
Step 3: Secure Necessary Pre-permitting Approvals
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
Before you can move on to the final step in the Canyon County ADU approval process and submit your ADU building permit, there are a few pre-permitting items you’ll need to take care of first.
Utility Approval
For utility approval, confirm with your jurisdiction’s Public Works office that you will be able to utilize your existing home’s water, sewer and gas or if new lines will be required. You’ll also need to contact Idaho Power to determine if you will need to install a new meter for your ADU.
Septic System Approval
It’s not uncommon to have a septic system in Canyon County and if you do, you’ll need to obtain accessory use approval from Southwest District Health as part of the pre-permitting process. When you apply for your building permit, you’ll need to include this approval. This is the case even if you don’t plan to hook up your new ADU to your existing septic system.
For more information on this approval and other relevant permitting information, see our article on the Canyon County pre-permitting process. As we noted in this article, you’ll also need to obtain Highway District approval if you plan to have separate road access for your ADU.
Floodplain Development Permit
If the ADU you are building falls within the 100-year flood zone, you must also submit a Floodplain Development permit before you submit your ADU building permit application. You can contact the relevant Canyon County floodplain administrator(s), for assistance with this step of the Canyon County ADU approval process.
Erosion Control Permit (Nampa)
Some ADU projects may also require an Erosion Control Permit. This permit is designed to help prevent soil and sediment from entering public waterways and drainage systems. If your ADU construction requires the movement of 10 cubic yards, you’ll need an Erosion and Sediment Control Permit. You can learn more and apply for an Erosion Control Permit on the City of Nampa website.
Step 4: Submit Your ADU Building Permit Application
Once you’ve secured all required pre-permitting approvals and other required permits, you can continue the Canyon County ADU approval process by submitting your building permit. Where you submit this permit depends on where your land is located. You may need to submit your permit directly to Canyon County or you may need a permit for your local municipality, as is the case with the cities of Nampa, Caldwell, and Middleton.
Canyon County Building Permit Application Links
Canyon County Building Permit Application
Nampa ADU Building Permit Application
Caldwell Residential Additions Building Permit Application
Middleton Building Permit Instructions
Once your plans are submitted, reviewed, and approved, you’ll have completed the Canyon County ADU approval process and be able to start building your ADU. If you have questions about building an ADU in Canyon County or are looking for an ADU builder, contact us for a free consultation.
Canyon County ADU Approval Process FAQs
Can I build an ADU in Canyon County?
Yes, as long as your property is zoned for residential or ADU use, you can build an ADU in Canyon County. You will need to adhere to any local municipality ordinances such as those in Nampa or Caldwell, when building your ADU in Canyon County.
How big can an ADU be in Canyon County, Idaho?
There is not currently a county wide maximum size for ADUs. The size of the ADU you build will only be limited by your property’s current zoning regulations and any local municipality’s ADU regulations.
How long will it take for my Canyon County ADU building permit to be approved?
All building permit timelines are subject to the timelines of the building department to which you submitted your permit. If your building permit was submitted to the Canyon County Building Department, you can track your permit status here.
How much does it cost to build an ADU in Canyon County?
The cost to build an ADU in Canyon County can vary depending on location, amount of land development work required, materials, size, design and more. To get an idea of the cost to build an ADU in Canyon County, select one of our ADU home plans and use our instant quote tool to get an estimated cost to build your selected ADU plan in Canyon County.
Additional Resources For the Canyon County ADU Approval Process
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