Preapproved ADU Plans are LIVE!

Are you building a separate mother-in-law house in your back yard or a space you can rent out to supplement your mortgage? If so, you’ll need an architectural design plan for an accessory dwelling unit, an ADU plan.

Choosing a preapproved ADU plan can make the initial part of the process simpler and shorter.

Acquiring a plan and getting it approved takes quite a bit of time. In addition to having someone create a design for you, you’ll need to get it approved by your jurisdiction before you build through a process called a plan review. Without preapproval, a plan review can take between two weeks and four months.

You can bypass all—or almost all—of this process if you live in one of the jurisdictions where the plans are preapproved. Select from a collection of preapproved ADU plans, which are already designed and have already gone through a plan review. (Site-specific requirements still need review, so it doesn’t eliminate permitting altogether, but it can shorten this part of the process significantly.)

Using preapproved plans also reduces the likelihood that you’ll need design revisions to address code compliance comments, which can save both time and money. Compared with a custom ADU, you also save the time and cost of developing the design and permit drawings from scratch.

Why ADUs?

ADUs are important to the overall housing picture because, in many communities in western Washington, we have a missing middle housing problem. Missing middle housing means that there’s a lack of housing that’s closer together than one single-family home per lot.

Our current housing planning default (one lot, one house) is a holdover from a turn toward suburban sprawl-style planning that springs, in part, from our dependence on cars. Middle housing prioritizes shared living spaces and more walkable neighborhoods.

People build ADUs for many different reasons. Some add living spaces to their properties because they love living in community with others. Some because it makes sense to provide a private living space for an aging parent, a young adult child, or a friend. Others add ADUs to supplement their income or offset their mortgage payments.

ADUs are good for communities with middle income people, providing housing options at a more reasonable cost. Preapproved ADU designs are good options for middle income homeowners who want to build an ADU but can’t afford to pay for a custom design.

Many jurisdictions in western Washington are catching the vision and smoothing the way for more middle housing by making permitting less difficult, reducing restrictions, and increasing the allowable square footage for ADUs.

Our ADU plans are free for lots of people

If you live in any of the following jurisdictions, you can get one of our ADU plans for free. Go directly to the jurisdiction’s web page noted on our ADU FAQs page to obtain the plan you like. You do not need to purchase anything from us. Contact your jurisdiction to find out how to ensure your eligibility and to find out how to obtain a copy of the plan. Here are the jurisdictions we partner with:

Olympia
Lacey
Tumwater
Yelm
Port Angeles
Kitsap County, including:
- Bremerton
- Bainbridge Island
- Port Orchard
- Poulsbo

Seattle includes one of our designs in a collection of reduced-cost ADU plans. See our Seattle DADU design. If you’re building in Seattle, you can purchase this planset at a discount, directly from us.

What happens after you have an ADU plan?

You might be able to use the ADU plan as-is. That’s because preapproved plans have already been reviewed for certain code requirements by participating jurisdictions.

Keep in mind, though, that a given plan is not automatically ready to build on every property. That’s because every building site is unique. You might still need a site plan, zoning review, utility information, stormwater information, septic or sewer coordination, tree or critical area review, energy documentation, structural coordination, and jurisdiction-specific forms.

The preapproved plan helps streamline the process, but it does not eliminate all site-specific permitting requirements.

Our ADU plans are beautiful and versatile

These plans are designed to be ADUs but that doesn’t mean they have to be. More and more people are using them as plans for a primary residence.

In that case, some have asked us to help modify them somewhat to accommodate their needs and vision. If you obtain one of our plans and want to stretch or lightly modify the plan, we can help. We modified one plan by adding a breezeway, a garage, and a second suite. We modified another by adding a porch and a larger great space.

They can also be used at scale. In Port Angeles, developers are building whole neighborhoods out of our ADU plans.

We love all of this. The plans, like all of our designs, are created with real living in mind. We pay attention to flow, natural light, and indoor-outdoor living. That’s why they work as ADUs, as primary residences, or even as groupings of houses. It’s all part of an ecosystem that’s making housing more affordable, more accessible, and more beautiful.

Here’s how it works

You can find all the details about how preapproved ADU plans work on our ADU FAQs page. But here’s a quick primer.

Obtain a plan

Go to your jurisdiction’s website if you live in one of the jurisdictions listed above to obtain a free preapproved ADU plan.
Go the Seattle ADUniverse website and view their qualifying reduced-cost ADU plans. Contact us to purchase our plans included in their gallery directly, at a reduced rate.
If you do not live in one of the above jurisdictions or in Seattle, you can contact us to purchase one of our predesigned ADU plans from us directly.

Determine what you need to do next

Once you’ve obtained a plan, it comes with a plan license that gives you permission to use it for one project on one property.

The plan license does not include site-specific services, such as:

Permitting work
Structural engineering
Civil engineering
Energy modeling
Interior design
Contractor pricing
Construction administration

You can determine which of these services you do or do not need by contracting with us or with another professional who can help you plan the project.

We are available for hire to help with any or all of these, as needed.

Create a site plan

Before you build, you will need a site plan, something that’s often required for permitting. It typically needs to show property lines, setbacks, access, parking, utilities, easements, topography, critical areas, and the proposed building location.

We can provide site planning services on an hourly basis and help you coordinate with other professionals you might need, depending on the conditions at your site. These might include a surveyor, a civil engineer, a septic designer, or other consultants.

Determine your timeline

A planning professional can help you understand how long it will take to finish your project. If you hire us, we will let you know where your project sits in our queue and how your site, jurisdiction, and scope affect the timeline.

Choose a contractor early

You can use any contractor you like with our preapproved ADU plans. We encourage you to get them involved as early as possible. Their early input on budget, constructability, schedule, and site logistics will save you lots of time and headaches down the road.

Information to gather before you contact us

If you decide to hire us to help after you have obtained one of our preapproved ADU plans, here’s information that would be helpful for us to know:

Your property address or parcel number
Your jurisdiction, if known
Whether the project is an ADU, guest house, primary residence, or other use
Any survey, septic, utility, or site information you already have
Your approximate budget
Your preferred timeline
The plan you are interested in
Whether you need modifications, site planning, or permitting support

Don’t worry if you don’t have all of this information quite yet. We can start where you are and help you figure out next steps.

Posted on November 06, 2026