Getting Approval for an Unregistered ADU

What is an Unregistered ADU?

An unregistered ADU is a second living unit on your property, that currently exists, but has not been approved by the city in which it is located (or by King County, if within an unincorporated area). There may be exceptions to what constitutes an ADU, so you will want to find out about this specifically for the area you are located in. For example, you may have a guest cottage or other use that is a separate living area, but would not be classified as an ADU in your geographic area.

What Does Getting 'Approval' Mean?

'Approval' is the process your city or county uses for making sure your ADU meets the requirements that make your ADU properly located, designed and constructed, in order to be compatible with your neighborhood and safe to live in. See the 'Basic Steps', 'applying for approval from your city' section for information about the approval process. Your application will be reviewed by your city and one of the two following scenarios will likely occur:

If You Already Meet The City's Requirements
Your ADU will be approved. If you meet all the requirements, you will not have to do any construction work. If your city requires one, you will need to record a covenant agreement or similar document. See 'Basic Steps', 'Record the city's covenant agreement'.

If Your ADU Requires Some Modification
You will follow the steps outlined in the 'Basic Steps' pages for making your application and going through the construction process applicable to your situation. If your city requires one, you will need to record a covenant agreement or similar document. See 'Basic Steps', 'Record the city's covenant agreement'.

What Do I Do If I Have An Unregistered ADU?

Your first step would be to make sure your unit would be classified as an ADU in your city. If your city considers it something else (e.g. a cottage unit), you may not have an unregistered ADU issue at all.

If you do have an unregistered ADU, then you will need to find out what modifications, if any, you would be required to meet local requirements. Discuss the matter with the officials in the area you live in. If you are worried about your local officials finding out you have an unregistered ADU, see 'Who can I contact…' below.

For your information, many required modifications fall under 'life-safety' issues (e.g. fire, electrical, mechanical, or building codes) to ensure your ADU meets minimum safety and building code standards. For example, you may need to put larger windows in your ADUs bedrooms) or add an outside entrance to your basement ADU, to allow appropriate exit in case of fire. You also may need modifications to your plumbing or wiring to make them safe or to have them work properly. These modifications may be minor or more extensive, depending on when your home was built and other details of your situation.

Amnesty Period

An amnesty period is a time period set by your city, during which you can get your ADU approved and registered with your city, and avoid the worry of fines or other penalties which you are subject to while your ADU remains unregistered.

Please Note: Most cities established an amnesty period at the time they initially adopted their ADU regulations. The amnesty timeframes are set only for a certain amount of time, and expire when the time frame ends. 

What Are The Benefits Of Getting My ADU Registered?

Having a living unit that you know is safe to occupy and meets the particular codes relevant to the age, type of structure and other details about your ADU. 

Having a registered ADU could increase the marketability of your home when you choose to sell it.

Having a registered ADU will make it possible for you or a future buyer to get a loan based on potential income from an ADU.

What If I Continue To Defer ADU Approval?

There can be legal consequences if you choose not to get your ADU approved and registered. Below are just some of the areas of concern if you choose not to register your ADU. There may be others as well. Please Note: This information is advisory only and is not necessarily an indication of any action the city you live in may actually take.

Your local officials want all living units, including ADUs, in their city to meet the applicable codes and regulations. However, you should know that if your officials become aware that you have an ADU and has not been approved, you could be issued a Notice of Violation (or similar document) and/or could be fined. If you fail to comply with the notice by going through the appropriate approval process (and getting your ADU registered), you may be subject to more substantial monetary fines. You may also be ordered to stop using or even remove the ADU, or be subject to other legal actions.

If you are renting out an unregistered ADU, you may have personal liability for an injury to your renter, particularly if the injury is due to the owners' failure to meet appropriate codes or regulations for a problem within the ADU which caused the injury. You may also be subject to other forms of liability as well.

There are disclosure requirements that must be met as part of the process of selling your home. In general, you are required to disclose conditions you know to be broken, unsafe, and perhaps illegal. If you do not disclose these things, you may have liability to the buyer.

Who Can I Contact About My Unregistered ADU?

Remember, if you live within a City with an amnesty program for unregistered ADUs, you may discuss your situation directly with city staff to find out what you need to do to get your unregistered ADU approved and registered. You may also wish to talk with an architect or contractor about what modifications you may need to make for your jurisdiction.


"I spent a lot of time worrying that the City would discover my ADU and fine me or worse. I'm glad I looked into getting it registered."



"If you have an unregistered ADU and live inside the City of Issaquah, their current amnesty period allows you to talk to city officials about your ADU situation without fear of fines or penalties. Be sure to take advantage of this opportunity."