United States accessory dwelling unit trends

Accessory dwelling units (ADUs) are experiencing increased popularity across the United States as a method to address housing needs, such as providing rental income or accommodating aging family members. Between 2018 and 2024, approximately 2.8 million ADU permits were issued nationwide. California leads the trend with 32% of all U.S. permits, while notable growth is also observed in Florida and Texas.

As the trend progresses, the focus has shifted toward the complexities of design and construction. Successful development depends on navigating local regulations, property constraints, and utility requirements. For example, Rhode Island state law allows owner-occupied residential lots to add one unit within an existing structure by right, though detached units remain subject to local municipal rules regarding size, setbacks, and sewer capacity.

Key construction considerations include utility connection costs, such as trenching for electricity and water, and the distinction between different construction standards. Builders must choose between detached guest cottages and attached units, such as garage conversions or attic suites, which can significantly impact permitting paths and overall budgets.