Once you have a finished set of plans for your ADU, it’s time to bring it to life! This involves navigating the local permitting process and finding a team that will complete the project. If you’ve hired an architect, they can help you with this process by serving as your advocate and liaison before, during and after construction. As the owner, you’ll be involved throughout the process to make final decisions and selections, but your team will do the majority of heavy lifting and project management for you.


ABSOLUTELY. You will need to get a building permit before starting construction of an ADU. Even if you have decided to buy a prefabricated ADU, you will still need a local permit and the design drawings that cover the site installation and improvements, along with site connections and details. Permits can be issued to either property owners or licensed contractors, and if you are working with a contractor, they should “pull the permit,” as there are associated legal responsibilities such as workers compensation coverage. Your architect and / or general contractor will coordinate with the local jurisdiction to fulfill permit requirements. This process often involves multiple steps and reviews by different departments. As the owner, you will be asked to pay fees and sign forms as needed by the jurisdiction.

The permitting process takes time and varies by jurisdiction considerably. In some cases, it can take a few weeks to pull a permit, but sometimes the process can take months. For certain ADU designs, the permit process timeline is set by state law to 60 days max. For many, the wait for the permit process to complete is a good time to interview and hire a general contractor.


How you select a contractor depends on your project approach from day one. If you are using a modular unit, a design-build approach or a negotiated agreement, the contractor is often selected early on. If you hired an architect to prepare a set of plans, you can select your builder using a competitive bid approach. Whatever process you follow, your architect can be with you the entire way, serving as a trusted advisor.

If you are bidding, it’s generally recommended that you get 3 bids (or more). It is important to personally interview potential builders, as a big part of the decision is based not just on the numbers, but on personality and business style. Sometimes the lowest bidder may not be your best choice!

Here are some things to consider before signing on the dotted line:








With a building permit in hand and a contract to implement the ADU, it’s time to start construction! If you’ve hired a general contractor, they will organize, manage and oversee all aspects of the construction project while communicating with you as the owner throughout the process. Because the construction process is complicated and typically involves many tradespeople, suppliers and issues to overcome, it should only be approached by professionals with training and experience. Although modest in size, ADUs are for most people not a ‘Do it Yourself’ kind of project since they generally involve all the same issues and complexities as building a new home!

Throughout the process, the owner will have to make many decisions and answer a lot of questions. Ideally your builder will give you a schedule of decision milestones up front. If you are working with an architect, they can assist you with the choices which include finishes, materials, fixtures and equipment. In addition, your architect can review work completed for conformance with the design drawings and advocate for you if there are issues to sort out along the way. A series of building inspections will also need to be signed off throughout each phase of construction.

It’s recommended to request a schedule for construction as part of the construction contract. Construction timelines, just like cost, tend to follow a bell curve. An average timeline for a new build is between  6 to 10 months. The short end of the bell curve could be ‘weeks’ and the long end ‘years’.

As you can see, there’s a lot involved in building an ADU project! There will be many eyes on the job, but it’s important for you as the owner to stay aware of what is happening, who is making decisions, and what’s coming up. If you do your research up front, you’ll be able to better anticipate opportunities and challenges before it’s too late to change course. The fact that you are reading this website puts you ahead of the game already!


When the contractor has finished their work and you have a Certificate of Occupancy, it’s finally time to move into your new ADU.

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