ADU Construction

Thinking About Building an ADU in Idaho? Start With These 5 Essentials

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Accessory Dwelling Units (ADUs) are becoming one of the most popular ways for Idaho homeowners to expand living space, add rental income, or create a private retreat for family members. If you’re considering building an ADU in Boise or anywhere in the Treasure Valley, there are a few critical things you need to know before you start swinging a hammer.

At Renaissance Remodeling, we specialize in helping homeowners design and build beautiful, functional ADUs that add value and comfort. Here are five essentials you should know before building your ADU.

1. Understand Local Zoning and Permits

Before anything else, make sure your property is eligible for an ADU. Boise, Meridian, and surrounding areas have specific zoning laws and building codes. For example, Boise allows ADUs in most residential zones but requires owner occupancy on the property (City of Boise ADU Guide).

Pro Tip: Always check with your local planning department first to avoid costly mistakes. If you need assistance understanding regulations, reaching out to a remodeling expert can make the process smoother.

2. Budget Wisely

Building an ADU is a major investment that can add long-term value to your home. Costs vary based on size, location, and design choices, but many well-designed detached units in Idaho fall between $150,000 and $300,000.

It’s important to account for:

  • Design and architectural fees
  • Permit costs
  • Utility hookups (water, sewer, electricity)
  • Landscaping adjustments

Many homeowners also take this opportunity to refresh existing spaces. For example, updating the main home’s kitchen or outdoor areas can enhance overall property value.

While adding an ADU can be expensive, it’s important to remember it is an investment, not just a cost. In addition to improving your quality of life, your home value will increase and many choose to use ADU’s for rental income. Regardless of your goal, an ADU can pay off. 

3. Prioritize Smart Design

An ADU should feel like a complete home—not just an added structure. Thoughtful layouts, efficient storage, and features like high ceilings can make a small footprint feel larger.

Planning how the ADU will be used in the future—whether as a rental, home office, workshop, home gym, or guest suite—can help guide design decisions. Drawing inspiration from comprehensive design-build projects can offer ideas for maximizing space.

4. Plan for Utilities and Access

Connecting utilities to a new ADU can be more involved than many homeowners expect. Extending water, sewer, gas, and electricity lines will likely require city inspections and permits.

It’s also worth considering how people will access the ADU. Separate driveways or private entrances often provide more convenience and privacy (and can even be required in some situations)

For detailed information on building requirements, visit the Idaho Division of Building Safety.

5. Choose the Right Remodeling Partner

Building an ADU requires careful coordination between design, permitting, and construction. Working with a team that knows local regulations and construction practices can help ensure a smoother process.

With large investments such as home construction and remodeling, experience really matters. We’ll say that again, experience really matters! We’ve heard many horror stories of inexperienced contractors taking on big jobs, only to go over budget, extend the schedule, cause safety concerns, and unknowingly break the law. With a big investment, it’s worth working with the pros.



Building an ADU in Idaho is a smart move—whether you want extra income, a private retreat, or a future-proof housing solution. With careful planning and the right team, you can create a space that adds both value and joy to your property.

Need more ideas? Check out our latest home remodeling blog posts for more inspiration by clicking here!