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Steel-framed tiny home at an early stage of the ADU building process, with exposed frame and roof skeleton

The Process of Building an ADU: What to Expect

Category: Permits & Approvals
Published: 08/12/2025
Updated: 10/15/2026

Building an Accessory Dwelling Unit (ADU) can be an exciting project, but it also involves a series of complex steps. From initial planning to the final walkthrough, working with an experienced ADU builder can help you navigate the process with ease. Here’s what you can expect when building an ADU.

Step 1: Initial Consultation

The process begins with an initial consultation, where your builder will evaluate your property and discuss your needs and goals for the ADU. During this phase, you’ll work closely with the builder to determine the best location for the ADU, the size and layout, and any specific design preferences you may have. The builder will also provide a preliminary estimate of the project’s cost and timeline.

Step 2: Design and Planning

Once the consultation is complete, the design and planning phase begins. This is where your ADU starts to take shape. You’ll work with the builder’s design team to create a custom layout that fits your property and meets your needs. Whether you’re looking for a small, functional space or a larger, luxurious unit, the design team will ensure that every detail is tailored to your vision.

Step 3: Permitting Process

Navigating the permitting process is one of the most critical steps in building an ADU. Your builder will handle all the necessary paperwork and submit the plans to the local building department for approval. This can take some time, depending on local regulations, but an experienced builder will work to expedite the process as much as possible.

Step 4: Construction

Once the permits are in place, construction can begin. The timeline for construction will vary depending on the size and complexity of the ADU, but most projects can be completed within a few months. During construction, your builder will manage every aspect of the build, ensuring that everything is completed to the highest standards.

Step 5: Final Walkthrough

Once construction is complete, your builder will conduct a final walkthrough to ensure that everything is in perfect condition. This is your opportunity to inspect the ADU and make sure it meets your expectations. If any adjustments are needed, the builder will address them before handing over the keys.

Frequently Asked Questions

Still have questions? Get in touch with our team and we will answer them straight.

Yes, in every jurisdiction we build in. A permanent ADU or tiny home on a foundation is a dwelling, and dwellings require permits for zoning, building, and usually utility connections. Anyone who tells you otherwise is either talking about a home on wheels, which is a different category with different rules, or steering you toward something you will have to fix later.

That depends on your zone, your lot size, and what is already on the property. Some lots qualify easily. Others need a variance, and a few will not work at all. This is the first thing we look at, before design and before any conversation about cost, because there is no point planning a build your lot cannot support.

Five, in order. First, a feasibility check on your property and zoning. Second, design and floor plan selection. Third, permit submittal to your jurisdiction. Fourth, construction. Fifth, final inspection and walkthrough. We handle the permitting and inspections, which is the part most homeowners least want to manage themselves.

It varies by jurisdiction, and it is the least predictable part of the schedule. City of Spokane, Spokane Valley, and unincorporated Spokane County each run their own review on their own timeline. We build permit review into the schedule from the start rather than treating it as a surprise, and we will tell you what your jurisdiction is currently running when we scope your project.

Typically several months from permit approval to final walkthrough, depending on the design, your site conditions, and the season we break ground. Site work on a difficult lot can add time. So can a design change mid-build, which is why we settle the plan before construction starts.

Not usually. Most of our clients start from one of our existing floor plans and adjust from there, which is faster and less expensive than a custom design from scratch. If you want something genuinely one-off, we can work with an architect. We will be honest with you about whether your project actually needs one.