Can I Build an ADU at My House?

Granny flats. In-law units. Backyard cottages. Secondary units. Whatever you call them, Accessory Dwelling Units are one of the primary tools states are using to address housing constraints. The rules and regulations governing the construction of ADUs vary significantly from state to state, and even between different municipalities within the same state.

To date, several U.S. states have implemented state-wide legislation to support or regulate the construction of Accessory Dwelling Units (ADUs). These laws typically aim to increase housing supply, provide more affordable housing options, or address housing shortages in urban and suburban areas. The legislation often sets guidelines that local municipalities must follow, although local governments may have additional rules. Here's an overview of states known for having state-wide ADU legislation:

California

California has been a leader in ADU legislation, enacting several laws to make it easier for homeowners to build ADUs by reducing regulatory barriers and limiting local government restrictions. The state has mandated that local zoning laws accommodate ADUs, streamlined the approval process, and adjusted utility fee requirements, among other measures.

Oregon

Oregon has also passed significant legislation to facilitate the construction of ADUs, particularly in cities with populations over 2,500 and in metropolitan service areas. The state has focused on eliminating barriers like minimum lot size requirements and parking mandates for ADUs.

Washington

Washington State has encouraged the development of ADUs to increase housing density and affordability. Legislation has been aimed at reducing barriers and encouraging local governments to adopt more ADU-friendly zoning regulations.

Colorado

Colorado has seen some movement towards state-wide ADU legislation, with efforts focused on encouraging local jurisdictions to allow ADUs to address housing shortages, although the specifics can vary widely by locality.

Minnesota

In Minnesota, Minneapolis has been notable for its zoning reforms that support the construction of ADUs as part of a broader effort to increase housing stock and density.

Vermont

Vermont has passed legislation to encourage the development of ADUs as a means to address its housing shortage, focusing on simplifying the permitting process and reducing local zoning barriers.

New Hampshire

New Hampshire requires towns to allow ADUs in residential zones, offering homeowners more flexibility to add housing on their properties.

Other States

Other states have considered or are considering legislation related to ADUs, reflecting a growing national interest in this form of housing as a way to address the affordable housing crisis.

It's important to note that even within states that have supportive ADU policies at the state level, local municipalities can have their own regulations that impact the ease of ADU development. These can include restrictions on size, location, occupancy, and design, among other factors.

Check out the HUTS Standard ADU Units.