Rear Additions In Washington DC

Author: Susan Isaacs | The Isaacs Team

Learn how DC Code §§ 306.3 and 306.4 impact rear additions on DC homes. Washington DC zoning laws restrict the size of rear additions to some home types.

§§ 306.3 and 306.4

These code updates were implemented to address concerns about excessively disproportionate rear extensions adjoining attached and semi-detached buildings in the R-2, R-3, R-13, R-17, R-20, and RF zones by adding language limiting a matter-of-right rear extension to such buildings, whether as an addition to an existing building or as new construction, from extending further than ten feet (10 ft.) beyond the farthest rear wall of an adjoining principal residential building on an adjoining property.

Take Note

  • Check for code revisions
  • Consult with experts 

What Types Of Properties Are Not Affected?

2017 Text Amendments Limit Rear Extensions

The restrictions do not apply to detached buildings because a detached building, including any rear addition, would be subject to side yard requirements that provide separation from adjacent buildings.
Are Special Exceptions Allowed?
The amendments allow a rear extension to extend further than ten feet (10 ft.) if approved as a special exception.
Where can I find the code?

DC Building Code (As amended in 2017)



1313 14th St
NW DC 20005

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