The objective of this council priority was to address barriers in the land use code through code updates that increase the allowance of accessory dwelling units in Boulder.

  1. Plan

  2. Community Engagement

  3. Design

  4. Complete

Current Phase
Community Engagement

Project Overview

The objective of this council priority was to increase the allowance of Accessory Dwelling Units (ADUs) in the community.


An accessory dwelling unit, also known as an “in-law apartment” or “garage flat” or “ADU,” is an additional living unit that has separate kitchen, sleeping and bathroom facilities, attached or detached from the primary residential unit on a single-family lot. The first ordinance allowing accessory dwelling units in Boulder was adopted in 1983. The regulations have been updated over time, with the most recent updates adopted in 2018.

Accessory dwelling units have been discussed as one tool to address Boulder’s housing challenges over the past decade or more to help provide “a diversity of housing types and price ranges,” which is a core value of the Boulder Valley Comprehensive Plan. The current regulations limit the percentage of ADUs within a certain radius in some zoning districts (a “saturation limit”) and establishes a waiting list for properties that are in areas that have reached their saturation limit.

ADU Evaluation

In 2022, city staff completed an evaluation to understand how the 2018 changes had impacted the development of ADUs in the city, and what barriers for ADUs might remain in the land use code. The saturation limit, floor area requirements, and general code clarification and process improvements were identified as key issues to address.

Latest News

City Council approved updates to the Accessory Dwelling Unit regulations in the land use code on May 4, 2023. These changes will apply to any ADU proposed on or after Sept. 1, 2023.

Email comments to Lisa Houde, Senior City Planner or share ideas on the BeHeardBoulder page.

Projected Timeline

  • Jul. – Oct. 2022: Initial scoping. Review 2018 analysis of Boulder’s ADU regulations. Identify laws and administrative actions that are barriers to the construction of ADUs in Boulder.
  • Nov. 2022: City Council study session to discuss scoping and options.
  • Dec. 2022 – May. 2023: Draft amendments to land use code. Meet with appointed boards, such as the Housing Advisory Board and Planning Board, to discuss options. Study session with Council on options. Adoption in late April - early May. Begin implementation of changes this summer.