Accessory dwelling units (ADUs) are changing the way people think about home ownership and housing flexibility. Whether it’s creating extra space for family, generating rental income, or building a private home office, ADUs offer big potential on a small footprint.

But before you start sketching plans or pricing materials, it’s important to understand where ADUs are allowed and where they’re thriving. Here’s a closer look at which states support ADU development and what’s driving their success.

State Regulations

ADU rules vary a lot depending on where you live. Some states have made it easy to build an ADU almost anywhere, while others still leave most of the decision-making to local governments.

To simplify this, we’ve created a quick-reference chart summarizing the ADU regulations in every state. It will give you a clear overview of whether ADUs are allowed and any key requirements you should know.

Where ADUs Are the Most Successful

While many states are making progress, a few stand out as leaders in the ADU movement. These states have created a friendly environment for homeowners, making it easier and more affordable to build.

• California: The state has passed several laws to cut through red tape, removing tricky rules like parking and owner-occupancy requirements. Those changes have made it faster and simpler to build, turning California into the most active ADU market in the U.S.
• Oregon: Oregon quickly followed suit, requiring most cities to allow at least one ADU on any single-family lot. Portland, in particular, has become a model city for ADU adoption, with a strong culture of flexible, sustainable housing.
• Washington: Washington has taken a creative approach to housing density. Recent legislation allows up to two ADUs on a single property in many urban areas, opening the door for more homeowners to create rental units, guest spaces, or multigenerational homes.
• Vermont & New Hampshire: These New England states might be smaller, but they’ve made a big impact. Both have statewide policies that encourage ADU construction to expand affordable housing and support more flexible living arrangements for families.

Even if your state isn't on this list, don't be discouraged. Many cities and counties have their own progressive ADU ordinances. It’s always best to check with your local planning department to get the most accurate and up-to-date information for your area.

Begin Your Studio Home Journey

Understanding ADU regulations takes some research, but it’s worth every minute. A well-designed studio home can open up your space, boost your property’s value, and give you more freedom to live the way you want.

Ready to explore the possibilities? Schedule a free consultation with one of our experts to learn more about our models and understand the project costs. Or, if you're feeling inspired, jump into our Design Center to design and price your studio home today.