What's Required in Baltimore
- No ADU use exists in the Zoning Code until Council Bill 26-0195 is enacted; it takes effect 30 days after enactment.
- Today: carriage houses existing on June 5, 2017 with at least 350 sq ft may become single-family detached dwellings (Zoning Code 15-504).
- Today: single-family to multi-family conversions only in R-7, R-8, R-9 and R-10, by ordinance in R-7 and R-8 (Zoning Code 9-701).
- Bill as introduced: ADU no greater than 75% of the principal dwelling's floor area, height no more than the house or district limit.
- Committee amendments: one ADU per lot, not on a multi-family lot, detached units not in front of the house (pending).
- State law: no new off-street parking within 0.75 mile of mass transit; no impact fee or excise tax under 750 sq ft (Ch. 197).
- Building permit with plan review ($125 application), all trade permits by licensed contractors, and a $45 occupancy permit (BFRCBC 109).
Can You Build an ADU in Baltimore City?
Not as an ADU yet. Maryland's 2025 ADU law (Chapter 197, HB 1466) says that on or before October 1, 2026, each legislative body shall adopt a local law authorizing accessory dwelling units on land zoned for single-family residential use. Baltimore's bill, Council Bill 26-0195, was introduced May 11, 2026; the Land Use and Transportation Committee recommended it favorably with amendments, but on September 28, 2026 the Council re-referred it to committee, where it sits as of October 2, 2026. It would take effect on the 30th day after enactment. Until then the Zoning Code has no ADU use.
Two paths exist today. An accessory carriage house that existed on June 5, 2017 and contains at least 350 square feet may be converted into a single-family detached dwelling, enlarged by no more than 20% in height or footprint (the bill would repeal this). And a single-family house may be converted to a multi-family dwelling only in the R-7, R-8, R-9 and R-10 districts, with conditional-use approval by ordinance in R-7 and R-8.
What Would the Pending Bill Allow?
As introduced, an ADU is a unit on the same lot as a principal dwelling, subordinate to it and no greater than 75% of its floor area, attached or detached, no taller than the district limit or the house, and allowed in the required rear yard. The committee amendments add one ADU per lot; lots with a detached, semi-detached or rowhouse principal dwelling but not a multi-family dwelling; no detached ADU closer to the front lot line than the house's front wall; an internal unit limited to 40% of the structure's gross floor area; and conforming status for second units lawfully established before September 1, 2026. Further floor amendments by Councilmember Parker are pending, so treat these details as provisional. State law also bars requiring new off-street parking within a 0.75-mile radius of a mass transit facility and bars impact fees or excise taxes on ADUs under 750 square feet.
Baltimore ADU Rules by Scenario
| What you are doing | City filing | Rule |
|---|---|---|
| Basement apartment in a rowhouse in R-5 or R-6 today | Not allowed; conversions only in R-7 to R-10 | Zoning Code 9-701 |
| Convert a carriage house of 350 sq ft or more that existed June 5, 2017 | Allowed as a single-family detached dwelling | Zoning Code 15-504 |
| 500 sq ft interior unit, priced as an alteration | $350 in fees + $18 tax + $125 application = $493 | BFRCBC 109.6.1(c), (p), 109.6.2, 109.6.3 |
| 600 sq ft detached unit, 7,200 cu ft | $447 in fees + $23 tax + $125 application = $595 | BFRCBC 109.6.1(a), (p), 109.6.2, 109.6.3 |
| Second unit after the bill is enacted | Building permit plus zoning review under new 15-501.1 | Council Bill 26-0195 (pending) |
| ADU within 0.75 mile of a transit station | City may not require new off-street parking | Md. Land Use 4-504 (Ch. 197) |
| Second unit already lawfully established before September 1, 2026 | Conforming under the committee amendments | CB 26-0195 committee amendment 6 |
What Would the Permits Cost?
Section 109 has no ADU line. An interior or attached unit is priced as an alteration ($0.30 per square foot, $50 minimum) or an addition ($10 per 1,000 cubic feet, $75 minimum), a detached unit as a new building ($10 per 1,000 cubic feet of gross volume, $150 minimum). Add the itemized trade lines, a $45 occupancy permit, the $125 plan-review application fee and the 5% permit tax. Interior example: $150 alteration, $40 plumbing, $60 for ten circuits, $55 mechanical and $45 occupancy make $493 with tax and application. Detached example: the $150 minimum, $95 plumbing and water and sewer lines, $102 electrical, $55 mechanical and $45 occupancy make $595. Utility connection charges are separate.
How to Get a ADU Permit in Baltimore
Check the bill's status
Look up Council Bill 26-0195 on the City Council's Legistar site; ADU rules apply only 30 days after enactment.
Check your lot and district
Find your zoning district and whether an existing carriage house or an R-7 to R-10 conversion gives you a path today.
Meet Zoning and Plans Review early
Call Zoning at 410-396-4126 and Plans Review at 410-396-3460 before paying for full drawings.
Apply in E-Permits
File the One and Two Family Combo Permit with drawings for plan review and the $125 application fee; add licensed trades.
Build, inspect, get occupancy
Pass footing, framing, rough-in and final inspections, then obtain the occupancy permit for the new unit.