Baltimore City ADU Rules 2026: Rowhouses, Carriage Houses, CHAP & HB 1466

Baltimore City and Baltimore County are separate zoning jurisdictions, and Baltimore City is now moving its own 2026 accessory dwelling unit law through the City Council. Council Bill 26-0195, introduced May 11, 2026, would add an ADU definition, a 75%-of-floor-area size limit, specific height standards and rear-yard relief. The committee recommended it favorably with amendment on September 24. A further hearing is scheduled for October 22 at 9 a.m.; no enactment number or final effective date is shown in the bill record checked October 8.

For the statewide comparison, use our Maryland ADU Rules by County & City tracker.

Legislative records checked October 8, 2026. The September 24 meeting records a favorable recommendation with amendment and a Pass result. The bill detail page still lists In Committee, with no enactment number. The committee calendar reschedules the October 8 hearing to October 22 at 9 a.m. This guide reports those records separately and does not infer final Council passage from the committee vote.

1. Quick answer: can you build an ADU in Baltimore City?

2. Baltimore’s actual 2026 ADU bill: Council Bill 26-0195

For Baltimore City, the most important 2026 document is not a generic housing proposal. It is Council Bill 26-0195 — Zoning – Accessory Dwelling Units. The bill was introduced May 11, 2026 and is assigned to the Land Use & Transportation Committee.

The bill detail page checked October 8 lists In Committee. The September 24 committee record shows Recommended Favorably with Amendment — Pass. These records establish a committee recommendation, not final enactment. Keep the first-reader proposals below separate from enforceable law, and check for later amendments and final Council action.

3. Baltimore rowhouse conversions are not automatically HB 1466 ADUs

This is the most important Baltimore-specific distinction. Maryland Land Use §§4-501 through 4-504 apply the state ADU framework to land where the primary dwelling is a single-family detached dwelling. A typical Baltimore rowhouse is therefore not automatically entitled to the HB 1466 ADU pathway simply because an owner wants a basement apartment or second unit.

Baltimore already regulates conversion of single-family dwellings to multiple dwelling units through its own residential-conversion rules. In the Residential Districts, current §9-701 allows conversion to a multi-family dwelling only in R-7, R-8, R-9 and R-10, and conversions in R-7 and R-8 require conditional-use approval by ordinance of the Mayor and City Council.

Section 9-703 further requires the converted property to comply with applicable bulk and yard regulations and occupancy rules while retaining residential character. Exterior modifications can trigger design review. Baltimore’s live Council docket also contains property-specific conversion bills, showing that this remains a real separate pathway in 2026.

4. Carriage houses: Baltimore already has a separate conversion pathway

Baltimore’s existing zoning code contains a highly specific carriage-house rule that predates HB 1466. Under §15-504, an accessory carriage house that existed on June 5, 2017 in a Residential District or OR District may be converted into a single-family detached dwelling if it contains at least 350 square feet of gross floor area and meets the other requirements of the Zoning Code.

If that existing carriage house is converted to a dwelling, the code says an alteration may not enlarge its building height or footprint by more than 20%.

General accessory-structure rules also matter. Current §15-501 says accessory structures must be on the same lot as the principal structure, generally may not occupy more than 50% of the required rear yard, generally may not exceed 15 feet in height, and must comply with district yard requirements unless another rule provides otherwise. If an accessory structure is attached to the principal structure by wall or roof construction, the code treats it as part of the principal structure.

5. Baltimore’s proposed 75% size rule uses floor area

Council Bill 26-0195 proposes defining an ADU as no greater than 75% of the floor area of the principal dwelling. That is more specific than Maryland’s statute, which sets the 75% relationship but does not itself define one universal measurement method.

Until the bill is enacted, however, we do not treat “75% of floor area” as Baltimore’s final operational permit formula. Amendments, agency interpretation or final zoning guidance could still affect what is included in floor area and what document an applicant must use to establish the principal-dwelling measurement.

Use our Maryland 75% ADU Size Guide & Calculator for the statewide measurement issue, but select a Baltimore-specific number only after the City publishes the final methodology.

6. The proposed rear-yard and height rules are a major urban change

Baltimore’s existing accessory-structure rules are built around rear-yard coverage, yard requirements and a general 15-foot height ceiling. The ADU bill would create a more specific rule for ADUs. For the broader state-law context, compare our Maryland ADU setback rules guide.

Under the first-reader text, the maximum ADU height would be the lesser of the zoning district’s allowed building height or the actual height of the principal dwelling. The bill would also allow an ADU to occupy required rear-yard and pervious-surface area and would list an ADU as a permitted rear-yard encroachment.

That proposal is particularly relevant to Baltimore’s narrow urban lots, but it is still proposed law. It also does not erase building-code, fire-safety, utility, historic-preservation or property-specific constraints.

7. Parking is different in Baltimore City: minimums were eliminated citywide

Baltimore City is fundamentally different from counties where ADU parking studies are a major issue. Council Bill 25-0065 was enacted as Ordinance 25-064 on November 3, 2025. Its stated purpose is to repeal requirements for a minimum number of off-street parking spaces by use type and establish certain parking maximums.

That means a Baltimore City homeowner should not begin with the assumption that an ADU must add one or two new off-street spaces. The City has already removed citywide minimum off-street parking requirements. Curb regulations, access, loading, driveway approvals, alley geometry and site-specific conditions can still matter, but the starting point is very different from Frederick, Montgomery or Howard County.

For comparison, see our Maryland ADU Parking Rules & Parking Study Tracker.

8. CHAP can become the urban equivalent of a second approval layer

If the property is in a Baltimore City local historic district or is a designated local landmark, exterior ADU work can require review by the Commission for Historical and Architectural Preservation (CHAP).

CHAP’s Authorization-to-Proceed application states that exterior changes to properties in Baltimore’s local historic districts and landmarks must be approved by CHAP or its staff, and that this approval must be obtained before receiving a building permit.

For an ADU project, that can affect a new exterior entrance, windows, dormers, roof changes, rear additions, a carriage-house conversion, exterior mechanical equipment, doors and other visible—or in some cases non-street-facing—alterations governed by the local historic guidelines.

9. Alley access: especially important for carriage houses and rear structures

Maryland’s ADU statute allows a local legislative body to prohibit full or partial conversion of an accessory structure into an ADU when the structure’s only vehicular access is from an alley. That authority is particularly relevant in Baltimore, where rear garages and carriage houses frequently front alleys.

Do not assume that every alley-facing garage or carriage house is prohibited. The state provision authorizes a local restriction; it is not an automatic statewide ban. The final Baltimore ordinance and permit guidance must be checked to see whether and how the City uses that authority.

10. Zoning approval is only one layer: building and occupancy rules still apply

Baltimore’s Building Code treats a dwelling unit as independent living facilities with permanent provisions for living, sleeping, eating, cooking and sanitation. Creating a second dwelling can therefore affect building-code and occupancy review even where the exterior work is modest.

The City’s Building Code states that detached one- and two-family dwellings and townhouses within the Residential Code scope use the Baltimore City Residential Code, while existing buildings undergoing repair, alteration, addition or change of occupancy are subject to the Maryland Building Rehabilitation Code pathway described by the City.

11. Before you spend money on a Baltimore City ADU, answer these 8 questions

1. Is the property in Baltimore City or Baltimore County? They are separate jurisdictions.
2. Is the principal home detached, semi-detached or a rowhouse? HB 1466’s state mandate applies specifically to a single-family detached primary dwelling.
3. What is the zoning district? Current rowhouse conversion pathways vary by district.
4. Is the rear structure a qualifying pre-June-5-2017 carriage house? If so, §15-504 may provide a separate existing pathway.
5. Is the property in a CHAP local historic district or a local landmark? Resolve preservation review before final exterior design.
6. Does the rear structure rely only on alley vehicular access? Track the final 26-0195 language and City’s use of the state alley-access authority.
7. Are you relying on proposed 26-0195 standards? Do not sign a plan or construction contract as though the first-reader bill is enacted.
8. Check the next hearing and final Council action. September 24 records a favorable recommendation with amendment. The next listed ADU hearing is October 22 at 9 a.m.; later amendments and Council action can still change the proposal.

12. What to watch after the October 1 deadline

After the September 24 committee recommendation, check the October 22 meeting record for further action. As of October 8, the bill detail page still lists In Committee with no enactment number. Do not treat the proposed standards as an effective ADU approval path.

After the hearing, the items we will compare are: the final definition of principal dwelling, whether rowhouses remain within the local bill’s scope, the 75% floor-area language, rear-yard/pervious-surface treatment, height, any alley-access restriction, permit procedure and final effective date.

For the statewide deadline, read What Happens If Your County or City Isn’t Ready by October 1?. For the nearby but legally separate jurisdiction, see Baltimore County ADU Rules.

Research changelog

• October 8, 2026: reconciled the September 24 committee recommendation with the bill page’s In Committee label; added the October 22, 9 a.m. rescheduled hearing. No enactment or effective date is inferred.
• September 24, 2026: the Land Use & Transportation Committee recommended Bill 26-0195 favorably with amendment; the official record shows the result as Pass. Official meeting record.
• September 20, 2026: verified the final September 17 meeting record; no action or result is displayed for Bill 26-0195, which remains In Committee with no enactment number.
• September 12, 2026: verified that Legistar still lists Bill 26-0195 In Committee and the September 17 hearing at 9:00 a.m.; no hearing result or final enactment is available.
• September 11, 2026: refreshed the legislative status and retained the Transition label.
• September 8, 2026: published the initial comparison of current Baltimore zoning pathways and proposed Bill 26-0195.

Primary sources used for this Baltimore City guide

• Baltimore City Council — Council Bill 26-0195, Zoning – Accessory Dwelling Units
• Baltimore City Council — September 17, 2026 Land Use & Transportation hearing
• Baltimore Zoning Code §15-501 — General accessory-structure regulations
• Baltimore Zoning Code §15-504 — Carriage houses
• Baltimore Zoning Code §9-701 — Residential conversions
• Baltimore Zoning Code §9-703 — Conversion standards
• Baltimore City Ordinance 25-064 — Eliminating Off-Street Parking Requirements
• CHAP — Authorization-to-Proceed application
• Baltimore City Building Code — scope and existing-building rules
• Maryland Department of Planning — HB 1466 ADU FAQ
• Maryland Land Use §4-504 — local ADU law requirements

For the full Maryland statewide framework, see our Maryland ADU Guide 2026. Maryland ADU Guide is maintained by Gijo John as an independent research publication. We prioritize enacted statutes, City zoning code, City Council legislative records, building-code material and CHAP guidance. Source-backed corrections can be sent to gijo.j@marylandaduguide.com.