D.C. Code § 6-601.07

For the purposes of this subchapter the height of buildings shall be measured from the level of the sidewalk opposite the middle of the front of the building to the highest point of the roof. If the building has more than 1 front, the height shall be measured from the elevation of the sidewalk opposite the middle of the front that will permit of the greater height. No parapet walls shall extend above the limit of height, except on nonfireproof dwellings where a parapet wall or balustrade of a height not exceeding 4 feet will be permitted above the limit of height of building permitted under this subchapter.