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How do I add an Accessory Apartment to my home?

Montgomery County Council adopted new and revised Zoning Ordinance regulations making it easier to secure permits for an accessory apartment unit for most agriculturally or residentially zoned properties.

Under the revised County Zoning Ordinance, homeowners who previously would have been subject to a conditional use process to secure “Attached Accessory Apartment” or “Detached Accessory Apartment” approvals will now only be required to demonstrate compliance with limited use requirements when applying to the Department of Permitting Services.

That streamlined process means the property is presumptively permitted if compliance with certain Code requirements can be established by the owner.

Under the new law, all Accessory Apartment permit applicants must meet at least eight specific requirements to gain approval. Applicants seeking Attached Accessory Apartments must also demonstrate compliance with between three to four additional requirements (depending on the zoning), while those seeking Detached Accessory Apartments must demonstrate compliance with two to three additional requirements (zoning dependent). Waivers for some of these requirements are available from the Hearing Examiner when appropriate.

Attached Accessory Apartments are now available as a limited use for properties located in the Agricultural Reserve Zone and most “Rural Residential” and “Residential Detached” zoning classifications.  Detached Accessory Apartments are now available as a limited use in many of the same zoning categories. Also, Detached Accessory Apartments are now available in the Rural Neighborhood Cluster zone where they were previously prohibited entirely.

This all comes as a result of Zoning Text Amendment (“ZTA”) 18-07 (County Ordinance 18-53), which was adopted on October 9, 2018 by the Montgomery County Council, sitting as the District Council of the Maryland-Washington Regional District for Montgomery County. The new laws took effect October 29, 2018.

As stated in a recent Montgomery County press release “Accessory dwelling units (also known as in-law suites, accessory units and by many other names), include living spaces constructed over garages, basement apartments and even tiny backyard homes.”

At McMillan Metro Faerber, P.C., our real estate lawyers are experienced in representing builders, developers, businesses and homeowners before the Planning Board, Board of Appeals, Department of Permitting Services, and other related county and state agencies.

For a consultation about whether your home is capable of securing accessory apartment approvals, please call Peter E. Ciferri at (301) 251-1180 ext. 307, or e-mail Peter at