The regulations surrounding ADUs (Accessory Dwelling Units) in Montgomery County, MD vary widely depending on how a given area is zoned. If have plans to build an ADU on a property you are planning to purchase or one that you currently own, it is important to be aware of the limitations placed on ADU development by the Montgomery county zoning ordinances.
I have compiled some helpful resources that provide the most up-to-date firsthand information on ADUs in Montgomery County.
ADU Zoning Maps
This map displays all of Montgomery County's zoning borders. You can search by address and view by layers, such as "Metro Station One Mile Buffers" which impact the parking space requirement for ADUs.
ADU Map for Montgomery County, MD
This map allows you to quickly identify areas where ADUs are permitted, along with location of currently constructed ADUs. Note that the map still identifies zones where there was previously a 300' or 500' distance requirement from other ADUs, but this is regulation is no longer in place.
ADU Size and Setback requirements
This is a quick guide explaining the general zoning and permitting requirements for ADUs in Montgomery County, MD
Scroll to Table 3.1.6 to view all permitted uses by zone. See the "Accessory Residential Uses" section of the table for guidance on ADU's
Find your zone (4.2 Agricultural, 4.3 Rural Residential, 4.4 Residential) to find the relevant setback requirements.
ADU licensing
ADUs in Montgomery County, MD are required to have a Class 3 License "regardless of whether they will be rented or not". Currently there is a $260 filing fee, a $230 public notice sign fee, and an annual $125 license fee (Takoma Park properties must obtain an alternate license through the City of Takoma Park).
Legislative Updates
Link to Maryland Senate Bill 891
The primary impact of Senate Bill 891 is the requiring of all jurisdictions to implement some form of ADU permitting, meaning that they cannot be banned outright