Accessory Dwelling Units: Model State Act and Local Ordinance

January 2021

By: AARP, Coralette Hannon
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Accessory Dwelling Units

This guide includes model state and local legislation to encourage the development of accessory dwelling units (ADUs). It includes extensive commentary, explaining the rationale for model provisions and the justifications for avoiding certain common practices, such as owner-occupancy restrictions and discretionary reviews and use permits.  It serves as an update to earlier models published under the same title in 2000.

It presents two versions of a model state act: (1) an "optimal" act that limits the authority of local governmens to prohibit ADUs and (2) a "minimal" act that explicitly authorizes local governments to permit ADUs.

The model local ordinance includes seven major sections:

  • General provisions
  • Standards
  • Utility connections and building codes
  • ADU application and review procedures
  • Fees
  • Legalizing ADUs