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KEY TAKEAWAY
Montgomery County updated its existing ADU zoning rules. Prince George’s County enacted a new framework, with a future effective date and related measures still pending. Permission does not guarantee feasibility.
“An ADU can be allowed under the zoning ordinance and still be difficult to build on a particular lot.”
Before designing an ADU, confirm the zoning standards, lot constraints, utility capacity, permits and any rental licensing obligations applicable to the property.
Maryland’s October 1 deadline for local accessory dwelling unit legislation has passed. For homeowners, that raises a practical question: what actually changed?
An accessory dwelling unit, or ADU, is a smaller independent home on a property with an existing house. It may be created within the house, attached to it, or built as a detached structure. The concept is simple. The regulations, naturally, are not.
Montgomery County has updated an existing ADU program. Prince George’s County has enacted a broader zoning framework, but its listed effective date is still ahead. And in both places, separate requirements can affect whether an ADU is actually buildable.
Montgomery County: Updating an Existing Program
Montgomery County already permitted ADUs, but the state law required adjustments to some of its local standards. The County adopted Zoning Text Amendment 26-06 on September 15, with an October 5, 2026 effective date.
The revised framework allows an ADU of up to 75% of the size of the primary single-family detached dwelling. It also updates where ADUs may be permitted and revises standards affecting detached units, including setbacks and parking. These changes can matter on smaller lots, where a few feet of setback or an additional parking requirement may determine whether a proposal fits. Still, a permitted use is not a blank check: building coverage, height, stormwater, construction codes and other requirements continue to apply.
Rental licensing is a separate question
Montgomery County’s Bill 41-26 proposes changes to ADU rental licensing, including removing an owner-occupancy requirement and providing certain fee waivers for qualifying affordable units. As of October 27, the bill remains under consideration; those provisions should not be treated as adopted law.
The distinction is worth keeping in mind. Zoning determines whether an ADU is allowed and under what physical conditions. Rental licensing may impose a different set of requirements before it can be leased.
Prince George’s County: A New Zoning Framework
Prince George’s County enacted CB-074-2026 on September 29 to establish ADU definitions, permissions and development standards in its zoning ordinance. The legislative record lists November 16, 2026 as its effective date.
The County also adopted CR-095-2026 to address the interval between the state’s October 1 deadline and the local legislation’s effective date. Homeowners considering immediate applications should confirm the applicable transition procedures with the County.
Meanwhile, CB-092-2026 proposes additional provisions touching on rental rules, short-term rentals, tree canopy and woodland conservation, impervious surface and sewage disposal. As of this writing, it remains pending.
These subjects are not side issues. A detached ADU may fit on a zoning diagram yet face practical limitations related to trees, drainage, or wastewater service.
What Maryland’s Law Changed - and What It Didn’t
Maryland’s HB 1466/SB 891 established a statewide direction: qualifying properties with single-family detached homes must have a path to ADUs, subject to statutory limitations on local restrictions.
But the state did not create one uniform building permit. Counties still administer zoning, construction approvals, environmental requirements and, where applicable, rental licensing. The result is greater consistency in whether ADUs can be considered, but important local differences in how they can be delivered.
“Allowed” Is Not the Same as “Buildable”
For a homeowner in Bethesda, Silver Spring, Hyattsville or College Park, the useful question is no longer just whether Maryland supports ADUs. It is whether the specific property can accommodate one. That means checking setbacks, lot coverage, existing structures, access, utilities, drainage, trees, and the cost of construction before getting too attached to a floor plan. A converted basement, an attached addition and a backyard cottage can face very different constraints, even on the same property.
Wondering whether an ADU could work on your property?
UrbanKind Consulting offers preliminary property reviews for homeowners in Montgomery and Prince George’s Counties. We can review your property's zoning, applicable ADU regulations, and potential restrictions to help you understand whether an ADU may be permitted and what questions need to be resolved before moving forward.
Contact UrbanKind to get started.
What Happens Next?
In Montgomery County, the next items to watch include implementation of the updated zoning rules and the fate of Bill 41-26. In Prince George’s County, attention turns to the November 16 effective date, transition procedures, and pending CB-092-2026.
Over time, the more revealing measure will be how many ADUs homeowners can actually permit and construct, not simply how many are theoretically allowed.
The statewide law opens a door. The next step is determining what can realistically be built on your property.
THE PRACTICAL NEXT STEP
If you are considering an ADU, start with a property-specific zoning and feasibility review—not a generic backyard cottage plan. Confirm what the county permits, what your lot can accommodate, and what approvals will be required.
The statewide law opens a door. The next step is determining what can realistically be built on your property.
RELATED READING
- Maryland Wants More ADUs. Now the Counties Have to Figure Out the Details.
- Can You Add an ADU to Your Property?
- What Does “By-Right” Actually Mean?
- Land Use Strategy & Early Project Planning
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