The purposes of the Naval Observatory Mixed-Use zone (MU-27) are to:

  • Permit moderate-density mixed-use development;
  • Promote the public health, safety, and general welfare on land adjacent to or in close proximity to the highly sensitive and historically important Naval Observatory, in keeping with the goals and policies of the Federal and District elements of the Comprehensive Plan and the adopted Master Plan for that facility;
  • Ensure that public land within the zone shall be used in a manner consistent with the historic or ceremonial importance and special mission of the Naval Observatory;
  • Reflect the importance of the Naval Observatory to the District of Columbia and the Nation;
  • Reduce or eliminate any possible harm or restrictions on the mission of the Federal establishment within the zone; and
  • Provide additional controls on private land, in order to protect Federal interest concerns, including the critical scientific mission performed at the Naval Observatory and the security needs of the Vice President's residence.

The MU-27 zone is intended to permit moderate-density mixed-use development.

Development Standards
Floor Area Ratio (max.)1 Height (ft.) Penthouse Height (ft.)/Stories Lot Occupancy
Rear Yard (ft.)2, 3, 4 Side Yard (ft.) Green Area Ratio Zoning Regulation Reference
MU-27 2.5 40 12
(1 story)
100 15 None required; however, if a side yard is provided it shall be at least 2 in. wide for each 1 ft. of height of building but no less than 5 ft. 0.30 Subtitle G, Chapter 8
3.0 (IZ) 15 ft. for mechanical penthouse space 8 ft. for a single-family detached or semi-detached dwelling
1.5 (non-residential)

Use Permissions Courts Parking Inclusionary Zoning
Subtitle U, Chapter 5 Subtitle G § 202 Subtitle C, Chapter 7 Subtitle C, Chapter 10

1 In the MU-27 zone, an existing building on a lot with an area 10,000 sq. ft. or less may have a maximum density of 2.0 FAR for nonresidential uses, provided the uses are located in the ground story and the story directly above the ground story.
2 A horizontal plane may be established at 25 ft. above the mean finished grade at the middle of the rear of the structure for the purpose of measuring rear yards.
3 Where a lot abuts an alley: (1) For that portion of the structure below a horizontal plane described in Subtitle G § 805.2 from the center line of the alley to the rear wall of the portion; and (2) For that portion of the structure above the horizontal plane described in Subtitle G § 805.2, from the rear lot line to the rear wall of that portion immediately above the plane; and
4 Where a lot does not abut an alley, the rear yard shall be measured from the rear lot line to the rear wall of the building or other structure.