Bel Air MD ADU Rules 2026: Current Approval Process & Maryland Deadline

Can you build an ADU in Bel Air? Bel Air already recognizes accessory dwelling units, but the approval path depends on your property. In the common R-1, R-2 and R-3 residential districts, an ADU is currently listed as SD — special development. In plain English: it is not simply an automatic building-permit approval; the Town says special-development requests go to the Planning Commission and require a public hearing.

Jurisdiction matters. A Bel Air mailing address does not necessarily mean the property is inside the incorporated Town of Bel Air. Properties outside Town limits generally fall under Harford County zoning. Use the Maryland ADU Jurisdiction Finder before relying on this guide.

This is a planning guide, not legal, zoning, architectural, engineering or permitting advice. Code text and pending legislation can change; verify your parcel and the current ordinance with the Town.

Bel Air ADU rules at a glance

Where does Bel Air currently allow an ADU?

Bel Air’s permitted-use table lists an accessory dwelling unit in R-1, R-2 and R-3 as a special development. The published table also lists the use as permitted in R-O and several business districts. That table is only a starting point: the code itself warns that the text controls if a table and the regulations conflict.

For a homeowner, the practical first question is therefore not simply “Does Bel Air allow ADUs?” It is: What is my zoning district, what is the existing principal dwelling, and what approval path applies to this parcel?

R-1, R-2 and R-3 homeowners should understand “special development”

The Town defines a special development as a use that may be authorized by the Planning Commission when the proposal complies with the applicable conditions and standards. Bel Air’s Planning and Zoning FAQ says a public hearing is required before the Planning Commission for special-development requests.

That distinction matters. A use appearing in the zoning code is not necessarily a ministerial building-permit approval. If your property is in one of these residential districts, ask Planning for the current special-development application requirements, review timeline, fees and required plans before commissioning a full construction set.

How large can a Bel Air ADU be?

The Town’s current definition describes an accessory dwelling as an independent dwelling on the same lot and accessory to a primary residential dwelling. Maryland’s statewide ADU framework defines an ADU, for purposes of the new state requirements, as a secondary unit on the same lot as a primary single-family detached dwelling that is subordinate in use and no greater than 75% of the size of the primary dwelling.

Do not treat 75% as a guaranteed buildable size. Lot coverage, setbacks, building configuration, utilities, fire/building code and any applicable Town performance standards can produce a smaller practical envelope. See our Maryland ADU size guide for the state measurement issue.

Detached ADUs: check the accessory-structure rules early

Bel Air’s general residential accessory-use rules say accessory buildings are generally placed in a side or rear yard, with residential accessory buildings at least six feet from alley lines and at least three feet from adjoining lot lines. The code also limits residential accessory structures to 20 feet in height or the height of the principal structure, whichever is less, subject to the detailed roof-height rule.

The same section states that total square footage of accessory uses or structures generally may not exceed 50% of the habitable space of the principal structure, while allowing a minimum of 480 square feet regardless of principal-structure size. These are general accessory-structure provisions, not a promise that a particular ADU can use the entire envelope.

Do not assume an extra parking space is required—or prohibited

Maryland’s 2025 ADU law places conditions on local governments that want to impose additional off-street parking requirements for ADUs, including a parking-study and waiver framework. Because Bel Air is approaching the October 1, 2026 compliance deadline, homeowners should ask the Town what parking standard applies under the final local implementation rather than relying on an older rule or a county rule.

This is one of the items we will update when Bel Air’s final state-alignment position is confirmed.

What changes on October 1, 2026?

Maryland Land Use § 4-504 requires covered local legislative bodies to adopt a local law authorizing ADUs in accordance with the state framework on or before October 1, 2026. Among other things, the state framework says an ADU must be excluded from density and residential-growth-limit calculations and prevents a local ADU side/rear setback from exceeding the jurisdiction’s existing accessory-structure setback.

The law does not mean every existing Bel Air zoning provision automatically disappears. It means the Town’s final local framework needs to be read together with the state requirements. Until the Town’s final compliance text is verified, this page separates the currently published Bel Air code from the statewide requirements taking effect through local implementation.

What a Bel Air homeowner should do now

1. Confirm the property is actually inside the Town of Bel Air. Do not rely on the postal city alone.
2. Confirm the zoning district. Ask whether the ADU is permitted or requires special-development approval.
3. Ask for the current HB 1466 implementation status. Request the ordinance number and effective date if a final compliance ordinance has been adopted.
4. Confirm the permitted ADU configuration and size. Ask how the Town measures the primary dwelling and the 75% state ceiling.
5. For a detached unit, verify setbacks, height, lot coverage and accessory-structure area.
6. Confirm parking and access requirements.
7. Check utilities and building permits. Zoning approval does not replace building, electrical, plumbing, mechanical or utility requirements.
8. Get the Town’s answer in writing where possible before committing to design or construction costs.

Bel Air vs. Harford County: which guide should you use?

Bel Air is an incorporated municipality with its own planning and zoning authority. If the parcel is inside Town limits, start with this Bel Air guide. If it is outside Bel Air, use the Harford County ADU Rules 2026 guide instead. Separate municipal guides are also available for Havre de Grace and other incorporated jurisdictions as we verify them.

Primary sources used for this Bel Air guide

• Town of Bel Air Code — Article III, zoning districts and ADU provisions
• Town of Bel Air Code — Article X, accessory and temporary uses
• Town of Bel Air Code — Article XIV definitions
• Town of Bel Air Planning & Zoning FAQ — special-development process
• Town of Bel Air — legislation archive
• Maryland Land Use § 4-504 — statewide ADU requirements
• Maryland General Assembly — HB 1466 / Chapter 197

Track statewide and local implementation in the Maryland County & City ADU Rules Tracker. Maryland ADU Guide is maintained by Gijo John as an independent research publication.