Roadmap to an ADU

First, what is an ADU?

An ADU (Accessory Dwelling Unit) is a secondary housing unit (not to be confused with a mobile tiny home!) on a residential lot. An ADU may be more commonly known as a mother-in-law suite, granny flat, cottage, or casita. They contain a kitchen, at least 1 bathroom and can be up to 2 bedrooms. ADUs may be up to 900 square feet, depending on the property and other factors. An ADU could be a converted basement or garage, attached to the primary home (bump-out) or completely separate from the primary.

Can I build an ADU on my property?

Many factors determine the feasibility of an ADU on your lot. A good place to start would be to find the zoning district your property is in with this zoning district tool. Then, you can research standard setbacks that apply to lots in your zone.

What is my purpose in building an ADU?

There are lots of great reasons to build an ADU, and knowing your intention will help you as you go through the process and make decisions.

  • Maybe your parents are getting older and having them closer but with their own space will benefit them and you.

  • Are you looking for rental income? Do you want a short-term vacation rental or longer-term tenants? These all have varying levels of involvement and management responsibility, so you’ll want to think about this!

  • An ADU can be a great solution for an adult child who is living at home as they save money to figure out the next step.

  • Do you work at home and would love to have a separate, dedicated workspace?

  • Would you like some extra space for when friends and family come to visit?

How would I finance building an ADU?

Renofi has great resources about financing options for an ADU. Also talk to your local banker about what options they may have for you, including a HELOC on your existing home.

What next?

Design a floor plan and site plan.

If you’re not already working with us, this is where we come in. We can help bring your vision to life and work with the city on the concept review. Then we’ll refer you to a drafter to create a full construction plan set that will be essential to the construction process.

Then, we’ll obtain the required permits from the City of Boise.

This can be a complicated process, and we can be the point on this.

Once we're all permitted, we’ll begin the build!