Attainable Accessory Apartments 2

Accessory apartments are already an important component of our housing in the District, as they are typically more affordable; they can help to make owning a house more affordable to a broader range of people by enabling homeowners to offset their mortgage; and they can allow older folks to age in place. That’s why it is so exciting that the Zoning Commission is considering new regulations that would be more permissive of accessory apartments.

Accessory Apartments 2

An accessory apartment is a complete residential unit located on a single family dwelling lot. It can be within the main house or in an accessory building, but it cannot be “sold off” as a separate unit – only rented out by the homeowner. It contains kitchen and bath facilities that are separate from those of the primary dwelling. In the District, the best-known examples of accessory apartments are “English Basements” located in rowhouses. However, many other homes throughout the District already have a rental suite. In our low density residential zones, the current Zoning Regulations allow the owner of a detached home to have an accessory apartment, but only with the approval of a Special Exception by the Board of Zoning Adjustment (BZA), and compliance with several requirements. A separate provision allows a homeowner in the lowest density zones (R-1-A and R-2-B) to have an additional accessory unit located over a garage, specifically for a “domestic” living on the site.

Accessory Apartments 3

The Zoning Commission has taken preliminary action to approve the proposed new regulations for accessory apartments.  The changes would, in many instances, remove the requirement for a Special Exception and allow them by-right, subject to meeting a list of conditions such as size of the house, and size of the apartment.  Many homeowners would not be required to go through a public hearing process, saving time and money, provided that all of the criteria are met.  If the criteria can’t be met, the homeowner could apply for a Special Exception to waive up to two of the requirements, which is similar to the current zoning provisions.

Take a look at the following table to see how the current and proposed regulations compare (click to enlarge).

Accessory Apartments



  1. I have a 2400sf (2 stories + basement) detached house in an R-4 district with a 1600sf lot and no alley access. The lot is just slightly too small for 2 units by right. Under the new rules, can I add an ADU by right? Also, can I add a front entrance since there’s no alley access?

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