Homeowner TA: Outreach Content – ADU 101
About this resource: The following content can be used in jurisdiction websites, handouts, and other outreach efforts to support homeowners in building an ADU. There are many opportunities to edit and expand this content, particularly to add in references and links to local programs, policies, and opportunities.
ADU 101
What is an ADU?
Accessory dwelling units (ADUs), also known as “granny flats,” “in-law units,” or “backyard cottages,” come in many shapes and sizes but are always a self-contained home that is usually smaller than the main house and legally part of the same property. They must have a kitchen, bathroom, and place to sleep, and can range from small studios under 500 square feet to larger homes with multiple bedrooms.
Why build an ADU?
Building an ADU is an investment in your property and your community. ADUs often provide homes for the local workforce and small families who have difficulty finding local housing that meets their needs. For homeowners, there are many reasons to build an ADU — rental income, safe and convenient housing for relatives, flexibility over time, and many others.
Here are some of the reasons why people build ADUs:
- Housing family. Close but independent living for adult children, aging relatives, or loved ones with special needs.
- Rental income. A steady source of additional income for retirement or a rainy day. Can come from the ADU or the main home.
- A home as you age. A nearby home for caregivers or for aging adults who want to rent their main home and live in their ADU.
- Extra hands. An extra set of eyes and hands on your property can be helpful for safety, when you travel, upkeep, and more.
- Community housing. Provide housing to families, workers, and others who might struggle to find something local.
Property investment Not only will you receive rental income in the short term, but your sale price and property value can increase too.
Types of ADUs
There are many different types of ADUs.
Detached: New freestanding structure separate from the main home, like a backyard cottage
Attached: New structure (may include some converted space) sharing at least one wall with the main home
Conversion: Converted existing space in the main home or on the property (bedroom, basement, detached garage)
Multi-family: Any of the above that is part of a multi-family building like a duplex, triplex, or apartment building (existing or proposed)
What’s not an ADU? RVs, tiny homes on wheels, yurts, and storage structures are NOT considered ADUs.
Project Timing
Building an ADU is an investment of time as well as money. Most projects take 12-24 months to complete, with interior conversions being the fastest.
Site-Built/Custom Design vs. Factory-Built/Prefabricated Units
Site-built/Traditional: A traditionally constructed ADU, built from scratch on your property (“stick-built”). This option typically allows for a lot of customization and smaller changes to be made throughout the construction process.
Prefabricated/panelized/modular: These ADUs are partially or mostly built in a factory, then shipped to your site to be put together. Sometimes the company will include all services in their fee (“turn-key”), including help with permitting and all on-site construction tasks (e.g., laying the foundation, utility hookups, etc.). Other times you’ll need to hire additional professionals to help.