Regarding Your Accessory Dwelling Unit in D.C. - Winthorpe Design & Build

Regarding Your Accessory Dwelling Unit in D.C.

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We have some urgent news for those living in DC! If you currently have or are in the process of building an accessory building on your residential lot, you need to be aware of recent zoning changes. The regulations regarding accessory buildings may put your existing building or new construction in peril.

One of these modifications increased allowable height and relaxed the requirements of alleyway separation. In D.C., the rules regarding essential rear yards for R-zoned lots can vary. What IS universal, though, is that the rear yard designation begins at the back of the main structure or dwelling.

In Wesley Heights and other parts of the NW D.C. area, it’s not uncommon to have a detached garage behind the house. New regulations on single-family lots demand a 25-foot separation for the rear yard to exist between the primary and accessory buildings. 

For most lots, the required setbacks and minimum lot depth for a front yard make the placement of an accessory infeasible unless you attain zoning relief.

How Do The New DCRA Accessory Building Regulations Affect Me?

If your Accessory Building violates one or more of the DCRA regulations, it is vital to resolve the issue immediately. Winthorpe Design & Build is currently working to establish and figure out the impacts of these new regulations on current projects in the permitting and planning stages.

Below are the most relevant regulation excerpts and clarifications made by the Zoning Administrator and a summary of how these clarifications affect the regulations. 

As always, you are welcome to reach out to us with questions about your Accessory Building’s compliance or the compliance of our projects relevant to these and other zoning requirements.

New Regulations According to the DCRA Website for Reference

(These quotes have been pulled directly from 11DCMR subtitle E, Chapter 50)

E-5002.1 “Height”

“The Maximum Permitted height for an accessory building in an RF zone shall be twenty feet (20 ft.) and two (2) stories, including the penthouse.”

The Zoning Administrator later made an important clarification regarding this and Section E-5004.2 (a) in Narrative of Zoning Administrator Interpretation. According to the Zoning Administrator in this revision, the intention was to “limit the height of an accessory building to 10 feet when it is located in the rear yard; outside of that required rear yard area, or elsewhere in the rear yard, such an accessory building may be built up to the 20 foot, 2-story limit accessory building height limit under E-5002.1.”

If you want to place an accessory building in the rear yard, its maximum height is dependent on whether or not it is within the minimum area (in feet from the back wall of the principal dwelling to the rear property line) required for your rear yard. If it falls in the minimum yard area, then the maximum height is 10 feet, and Section E-5002.1 does not apply. If it’s located in the rear yard but does not infringe on the minimum required area, it must adhere to Section E-5002., as does any accessory building placed outside the rear yard.

E-5003.1 “Lot Occupancy”

“The maximum lot occupancy for an accessory building in an RF zone shall be the greater of thirty percent (30%) of the required rear yard area or four-hundred and fifty square feet (450 sq. ft.).”

The Narrative of Zoning Administrator Interpretation made a crucial clarification on this section, as well. It states that this section was meant to be a Maximum Accessory Building Footprint limitation and that the title is likely a misnomer. It says, “The provision denotes a limit that references 30% of the required yard area, which is irrespective of the location (whether or not such an Accessory Building is actually within the required yard).” The Zoning Administrator also clarified that the Accessory Building Area “is added to the building area or building footprints on the lot, for an overall maximum permitted lot occupancy.”

This clarification means that the Accessory Building’s location on the lot should not be factored in when calculating the number of people allowed to occupy your property. The area (and a few other features) of the Accessory Building, on the other hand, should be.

E-5004.1 Rear Yard

“No minimum rear yard is required for an accessory building in an RF zone except when abutting an alley, where it shall be set back at least twelve feet (12 ft.) from the centerline of the alley.”

E-5004.2 Rear Yard

“An Accessory Building shall be permitted in a required rear yard of a principal building pursuant to the following conditions:

(a) “The Accessory Building is less than ten feet (10 ft.) in height; and

(b) “The Accessory Building is less than one hundred square feet (100 sq.ft.) in gross floor area (GFA).”

Once again, the Narrative of Zoning Administrator Interpretation had some significant clarifications regarding the regulations stated above. The revisions for E-5004.2 (a) are included in those of E-5002.1 listed with that section. The modifications to Section E-5004.2 (b) state that the section applies only when the Accessory Building in question lies within the required rear yard. This rule allows only a small storage shed-like Accessory Building in this required rear yard. 

The revision then goes on to say, “Beyond that, if there is room on the lot, then a larger Accessory Building that may be suitable for a dwelling unit can be sited – typically closer to a rear lot line, and to an alley, if one is present.”

E-5004.3 Rear Yard

“If the required rear yard of the principal building in which the Accessory Building will be placed abuts an alley, the Accessory Building shall be set back at least twelve feet (12 ft.) from the centerline of the alley.”

Let Us Help

These code revisions may affect you and your property, depending on the size of your lot and the placement of your outbuildings. For help navigating these and other building codes, contact Winthorpe Design and Build, and let us take care of the headache for you.  

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