Building an ADU in Baltimore City

Baltimore City, not Baltimore County

Baltimore City and Baltimore County are separate local governments with separate zoning codes. This page covers Baltimore City, whose zoning rules are in Article 32 of the Baltimore City Code. Maryland's Land Use Article lists the provisions that apply to Baltimore City, and the list includes "Title 4, Subtitle 5 (Accessory Dwelling Units)," the state ADU law. For the statewide rules, see our Maryland ADU page. [1][6]

Where things stand: no ADU rules in the code yet

Maryland's HB 1466 says "On or before October 1, 2026, each legislative body shall adopt a local law authorizing the development of accessory dwelling units." The state law "applies only to the development of accessory dwelling units on land with a single-family detached dwelling unit as the primary dwelling unit."

Baltimore City's Zoning Code, as posted by the city on November 3, 2026, has no definition of "accessory dwelling unit" and no ADU use. The city Planning Department's staff report on Council Bill 26-0195 says the bill "will create and define accessory dwelling units (ADUs) within the zoning code as required by" HB 1466 and SB 891.

Council Bill 26-0195 was introduced on May 11, 2026. The Land Use and Transportation Committee recommended it favorably with amendments on September 24, 2026, and it was re-referred to committee on September 28. Hearings set for October 8 and October 22 were canceled, and the city's legislative record shows the hearing rescheduled for November 5, 2026. Until the City Council passes an ADU law, ask the DHCD Zoning Office at 410-396-4126 how it will handle an ADU application on your lot. [1][2][3][4][5][7][9]

What Council Bill 26-0195 would allow

As introduced, the bill defines an ADU as a dwelling unit "located on the same lot as a principal dwelling," "subordinate in use to the principal dwelling," and "no greater than 75% of the floor area of the principal dwelling." It can be a separate structure or attached to the main dwelling. Its height would be capped at the lesser of the district's maximum building height or "the actual height of the principal dwelling on the lot," and it "may occupy the area of rear yard and pervious surface required in the zoning district."

The Land Use and Transportation Committee's amendments, dated September 28, 2026 and marked "To be offered on the Council floor," would:

• change the 75% limit from "floor" area to "lot" area for an attached or detached ADU, and limit an ADU built within the same structure as the main dwelling to "no more than 40% of the gross floor area of the structure";
• allow "no more than 1 accessory dwelling unit" on a lot;
• keep a detached ADU from being closer to the front lot line than the front wall of the main house, except when it converts an accessory structure that lawfully existed before September 1, 2026 without changing its location or enlarging it;
• not count an ADU as a dwelling unit when figuring the maximum number of units allowed on a lot;
• allow an ADU on a lot whose main dwelling is detached, semi-detached or a rowhouse, but not a multi-family dwelling;
• have DHCD keep a public database of all ADUs and ADU construction permits;
• repeal the current carriage house section; and
• treat a second dwelling unit "lawfully established on a lot as a second dwelling unit prior to September 1, 2026" as conforming.

A separate amendment by Councilmember Parker would strike the language allowing an ADU within the same structure as the main dwelling. None of these amendments is law yet, and the bill can still change. Follow it on the City Council's legislation page for 26-0195. [7][10][11][12]

How the bill compares with state law

State law defines an ADU as "not greater than 75% of the size of" a single-family detached main house, and the Maryland Department of Planning says local governments "may not limit the size of ADUs to anything below the 75% limit." A local ADU law must leave ADUs out of density calculations, and "may not establish setback requirements that exceed the existing accessory structure setback requirements from the side and rear lot lines." It may add off-street parking requirements only after a parking study, and with a waiver process.

The city's Law Department told the Council that the bill reaches further than state law: its definition covers any lot with a "principal dwelling," while the state law only requires ADUs with single-family detached homes. The Law Department wrote that this "is not illegal." The bill and the committee amendments contain no owner-occupancy or parking requirement for ADUs. The Maryland Department of Planning says HB 1466 doesn't require by-right approval, and the bill as posted doesn't say what approval process an ADU would need, so confirm with the Zoning Office once it passes. [5][10][11][13][14][15]

Rowhouses, conversions and carriage houses today

Converting a house to more units. Under the current code, converting a single-family dwelling to a multi-family dwelling is allowed "only in the R-7, R-8, R-9, and R-10 Districts," and in R-7 and R-8 it also needs "conditional-use approval by Ordinance of the Mayor and City Council." The converted building must still meet its district's bulk and yard rules, including lot area per dwelling unit. The Planning Department's staff report says an ADU under Bill 26-0195 would be an accessory use and "is therefore not subject to the conversion standards of § 9-701," and the committee amendments say adding an attached or internal ADU "does not constitute a residential conversion."

Carriage houses. Section 15-504 says "An accessory carriage house existing on June 5, 2017, in a Residential District or in an OR District may be converted into a single-family detached dwelling" if it has at least 350 square feet of gross floor area and meets all other code requirements. A converted carriage house can't be enlarged by more than 20% in height or footprint. The code defines a carriage house as a two-story accessory structure "formerly used or intended to be used for the storage of horses and carriages." The committee amendments to Bill 26-0195 would repeal this section.

Accessory structures in general. Today, all accessory structures together may not cover more than 50% of a required rear yard, and unless the code says otherwise, an accessory structure can't be taller than 15 feet. An accessory structure attached to the main building by a wall or roof counts as part of the main building. [1][2][4][11][16]

Permits and fees

Building permits in Baltimore City come from the Department of Housing and Community Development (DHCD) through its E-Permits online system; you can also apply at the kiosk at 417 E. Fayette Street. DHCD says you need a permit for "Constructing, enlarging, altering, repairing, rehabilitating, demolishing (interior and exterior), or moving any structure" and for "Changing the use of land or any structure." Start on DHCD's Building Permits page.

DHCD says building permit fees are set by the Baltimore City Building Code, Section 109, and depend on the type of building and the kind and amount of work. It offers a downloadable fee estimator that adds up the permit fees, the application fee, any plan review fee and the 5% Building Code permit tax. DHCD's example, renovating 1,400 square feet of a rowhouse with plumbing, electrical and a new water heater, with plan review, comes to about $737; DHCD calls this "an estimate, not a bill," and the estimator leaves out fees charged by other agencies and water and sewer connection charges. Ask DHCD for the fees on your ADU project.

Permits for properties in city historic districts (CHAP), the floodplain, or projects needing design review or forest conservation review get referred to other agencies. See DHCD's special referrals page. [17]

Renting it out

Baltimore City's rental licensing law (City Code Article 13, Subtitle 5) covers "any non-owner-occupied dwelling unit in a 1- or 2-family dwelling that is leased or rented." The code counts a unit as non-owner-occupied if it "is not occupied by an owner of record," and "an owner may only have one owner-occupied dwelling unit in Baltimore City." No one may rent a rental dwelling "without a currently effective license" from the Housing Commissioner.

To get a license, every unit must be registered and paid up, the property must pass an inspection by a Maryland-licensed home inspector registered with DHCD (done no more than 90 days before you apply), and it must meet lead paint laws. A license lasts two years. The annual registration fee for a property with one or two dwelling units is $30 per dwelling unit. Violations are misdemeanors with fines up to $1,000, and "Each day that a violation continues is a separate offense." Ask DHCD's non-owner-occupied property line at 410-396-3575 how registration and licensing apply to an ADU on your lot.

Short-term rentals. You need a short-term residential rental license from DHCD, and the code says "a person may only be issued a short-term residential rental license for his or her permanent residence," meaning a dwelling unit where you live at least 180 days a year. The license fee is $200 per dwelling unit for two years, and your license number must appear in every listing. The Maryland Department of Planning says HB 1466 "does not alter a local government's powers to regulate short-term rentals." [8][14][18][19][20]

Permit steps in Baltimore

1. Confirm you're in Baltimore City and check your zoning

   Make sure your property is in Baltimore City (not Baltimore County), then call the DHCD Zoning Office at 410-396-4126 to learn your zoning district and whether an ADU, carriage house conversion or residential conversion is possible on your lot under the current code. [2][16][17]

2. Check the status of Council Bill 26-0195

   ADU rules depend on whether the City Council has passed Bill 26-0195 and in what form. Check its legislation page. [7]

3. Check for special referrals

   Find out whether your property is in a city historic district (CHAP), the floodplain or a design review area, since those permits get extra review by other agencies. [17]

4. Estimate fees and apply through E-Permits

   Use DHCD's fee estimator, create an E-Permits account and submit your building permit application from the Building Permits page. Pay the fees online or at the One-Stop Shop Permit Center before the permit is issued. [17]

5. Pass inspections

   Schedule building inspections with DHCD; call Building Inspections at 410-396-3470 with questions. [17]

6. Register and license a rental

   Before renting a unit you don't live in, register it, have it inspected by a DHCD-registered, state-licensed home inspector and get a rental license from the Housing Commissioner. [8][18]

Who to call

• Baltimore City DHCD, Permits and Zoning

  Building permits, zoning questions (Zoning Office 410-396-4126), plans review (410-396-3460) and inspections (410-396-3470); email DHCD.Permits@baltimorecity.gov

  443-984-1809

  417 E. Fayette Street, Baltimore, MD

  [17]

• Baltimore City DHCD, non-owner-occupied properties

  Registration and rental licensing requirements for non-owner-occupied properties

  410-396-3575

  [19]

• Baltimore City Department of Planning

  Staff reports to the Planning Commission on zoning bills, including Bill 26-0195

  417 East Fayette Street, 8th Floor, Baltimore, MD

  [4]

Questions people ask