Howard County Council approves expanded ADU rules after extensive amendments

Howard County Council on Tuesday approved Council Bill 3 (Zoning Regulation Amendment 2-18), a package of rules to allow accessory dwelling units (ADUs) by right in multiple zoning districts, after an extensive set of amendments and sustained debate. The final measure adds definitions that prohibit using ADUs as short-term rentals, preserves existing limits on two-family dwellings, requires owner-occupancy in most cases, and includes new plot-plan and stormwater language intended to protect neighboring properties.

Council members moved and voted on at least nine amendments and sub-amendments to the bill. Amendment 1 added a definition for short-term rentals and clarified that ADUs cannot be operated as short-term rentals; an amended version of Amendment 3 restored ADUs to count against lot-coverage limits and adjusted maximum square-footage thresholds. On stormwater and neighbor impacts, a council member explained that plot plans must show that an ADU will not adversely impact the neighborhood’s stormwater conveyance, or must mitigate impacts: “The plot plan that gets submitted has to show that you're not going to impact the neighbor's properties or, if you have facilities that are part of the neighborhood conveyance, you can't interfere with those,” a council member said.

Parking was a recurring concern. Council members debated whether increasing off-street parking requirements would require a county parking study under state ADU law; one staff speaker clarified that a parking study would be needed to justify requiring additional off-street spaces because state law limits local changes to ADU parking without a study. Opponents cautioned that increasing required impervious surface could worsen stormwater impacts and that parking patterns vary widely across neighborhoods.

The council voted to approve CB3 as amended. Supporters argued the rule changes will expand housing options for seniors and caregivers and help younger adults find housing in the county; dissenting members warned of risks to neighborhood character and planning coherence. The council’s approval sends the amended zoning rules forward for implementation under the county code.