About
An Accessory Dwelling Unit is a small, independent living space built on the same lot as a main home. It can be added to properties with single-family or two-family houses.
Overview
Howard County’s Accessory Dwelling Unit (ADU) initiative is guided by a zoning update titled, Zoning Regulation Amendment (ZRA‑218). This update helps the county meet the requirements of Maryland Law (HB-1466) and supports the long-term goals in the county’s General Plan, HoCo By Design, in addition to the county’s Housing Opportunities Master Plan. By creating clear rules and aligned policies, Howard County is working to expand flexible, diverse, and accessible housing options for residents.
Understanding Accessory Dwelling Units
Accessory Dwelling Units have existed in Howard County for more than a decade. A recent change to state law requires each county to update their zoning laws to help expand housing across the region. The resources linked below can help you learn more about Accessory Dwelling Units and potential changes within the County.
Legislation
MD HB 1466
Examine Maryland HB 1466 requiring local government to adopt a local law authorizing the development of accessory dwelling units to meet the housing needs of Maryland residents.
Howard County Proposed Code
Explore the essential details of Accessory Dwelling Units in Howard County, including what's changing, how they work, and what they mean for our community.
Frequently Asked Questions
What is an Accessory Dwelling Unit (ADU)?
An ADU is a smaller, independent home located on the same property as a single-family detached, attached, semi-detached and two-family dwelling. An ADU provides complete, independent living facilities for at least one person which includes at a minimum: a bathroom, a kitchen, and sleeping
area.
What is the maximum size allowed for an ADU?
The maximum allowable size is calculated from the exterior footprint of the principal dwelling, and the accessory unit must not exceed 75% of that footprint.
Is the property owner required to live on site?
Yes. The Property Owner must reside either within the principal dwelling or within the ADU.
What is the max number of people who can live in an ADU?
Under current county code, dwellings can host a max of 8 unrelated or 2 or more related persons occupying the dwelling— ADUs will be treated the same.