About
An Accessory Dwelling Unit is a small, independent living space built on the same lot as a main home. Examples of ADUs include small, detached cottages, garage apartments, townhome basement units, and in-law suites.
Overview
Council Bill (CB) 3-2026, created to expand opportunities for the construction of accessory dwelling units, was signed into law on February 6, 2026, and will be effective beginning April 8, 2026. CB3-2026 aligns Howard County Government’s zoning regulations with the broader goals of the County’s HoCo By Design General Plan and Housing Opportunities Master Plan, as well as the State’s recently adopted ADU law (House Bill (HB) 1466). CB 3-2026 allows single family homeowners to either construct attached and detached ADUs or renovate existing space to accommodate an attached ADU, in various residential zoning districts. Examples of ADUs include small, detached cottages, garage apartments, townhome basement units, and in-law suites.
What's New!
- Council Bill (CB) 3-2026 was signed into law on February 6, 2026, and will be effective beginning April 8, 2026.
- Review the list of Amendments included in CB3-2026 below under "Legislation"
Legislation
Examine resources related to 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 including legislation, frequently asked questions, task force reporting, and focus groups.
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.
Below are highlights of several amendments made to the original petition.
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ADU's shall not be used as short-term rentals
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ADU's shall not be permitted on lots with two-family dwellings
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Maximum lot coverage standards are outlined for all detached accessory structures (including ADU's)
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Add a lot coverage maximum for ADUs in the planned service area and exempts lot coverage specifically for properties zoned RC and RR
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Limit of one detached or attached ADU per lot developed with single family detached dwellings
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Limit of one attached ADU per lot developed with single family attached or semi-attached dwellings
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Property owner developing an ADU must ensure stormwater runoff will be mitigated and not impact neighbor properties
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Increase of off-street parking per ADU from one space to three spaces (exceptions allowed)
Frequently Asked Questions
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.
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.
Yes. The Property Owner must reside either within the principal dwelling or within the 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.