D.C. Mun. Regs. r. 11-336
Conversion of an existing residential building existing prior to May 12, 1958, to an apartment house shall be permitted as a special exception in the R-4 District if approved by the Board of Zoning Adjustment under § 3104, subject to §§ 336.2 through 336.14.
The maximum height of the residential building and any additions thereto shall not exceed thirty-five feet (35 ft.), except that the Board of Zoning Adjustment may grant a special exception from this limit under § 3104, subject to §§ 336.3 through 336.14.
The fourth (4th) dwelling unit and every additional even number dwelling unit thereafter shall be subject to the requirements of Chapter 26, Inclusionary Zoning, including the set aside requirement set forth at § 2603.9.
There must be an existing residential building on the property at the time of filing an application for a building permit.
There shall be a minimum of nine hundred square feet (900 sq. ft.) of land area per dwelling unit.
Any addition, including a roof structure or penthouse, shall not block or impede the functioning of a chimney or other external vent on an adjacent property required by any municipal code.
Any addition, including a roof structure or penthouse, shall not interfere with the operation of an existing or permitted solar energy system on an adjacent property, as evidenced through a shadow, shade, or other reputable study acceptable to the Board of Zoning Adjustment.
A roof top architectural element original to the house such as a turret, tower, or dormers shall not be removed or significantly altered, including changing its shape or increasing its height, elevation, or size.
An addition shall not extend further than ten feet (10 ft.) past the furthest rear wall of any principal residential building on an adjacent property.
Any addition shall not have a substantially adverse effect on the use or enjoyment of any abutting or adjacent dwelling or property, in particular:
In demonstrating compliance with § 336.10, the applicant shall use graphical representations such as plans, photographs, or elevation and section drawings sufficient to represent the relationship of the conversion and any associated addition to adjacent buildings and views from public ways.
The Board of Zoning Adjustment may require special treatment in the way of design, screening, exterior or interior lighting, building materials, or other features for the protection of adjacent or nearby properties, or to maintain the general character of a block.
The Board of Zoning Adjustment may modify or waive not more than three (3) of the requirements specified in §§ 336.6 through 336.9; provided, that any modification or waiver granted pursuant to this section shall not be in conflict with § 336.10.
An apartment house in an R 4 Zone District, converted from a residential building prior to June 26, 2015, or converted pursuant to §§ 3202.8, 3202.9, or 3202.10, shall be considered a conforming use and structure, but shall not be permitted to expand either structurally or through increasing the number of units, unless approved by the Board of Zoning Adjustment pursuant to §§ 3104.1 and 3104.3 and this section.
D.C. Mun. Regs. r. 11-336