D.C. Mun. Regs. tit. 14 § 708
Stairways, steps, and porches shall be firm, and the walking surfaces shall be sufficiently smooth so as to be readily cleaned and provide safe passageways free of tripping hazards.
Treads shall be reasonably level and in any flight evenly spaced.
Interior stairs more than two (2) risers high shall have an enclosing wall, balustrade, or other guard on each side, and shall have a handrail on at least one side.
All stair well openings shall have a balustrade or other guard along the entire length of any open or otherwise unprotected side.
Open porches forty-two inches (42") or more above the ground shall have balustrades or other guards not more than forty-two inches (42") in height along the entire length of any open, unprotected side.
Open porches less than forty-two inches (42") but more than twenty-four inches (24") above the ground shall have balustrades, or other guards not more than forty-two inches (42") in height or a top rail not more than forty-two inches (42") above the porch floor with an intermediate rail approximately midway between the floor and top rail along the entire length of any open unprotected side.
Exterior flights of stairs more than twenty-four inches (24") in height, attached to buildings or an appurtenance of buildings, including a porch or landing, shall be protected with a handrail, balustrade, or other guard on at least one side.
If an exterior flight of stairs extends more than forty-two inches (42"), each side of the stairs shall be protected by either a handrail, balustrade, or wall.
If an exterior flight of stairs is protected by two (2) walls, one shall have a handrail which will clear the wall by not less than one and one-half inches (1½") to provide maximum safety.
The vertical distance from the top of any handrail, balustrade, or other guard to the surface of any platform or front edge of any stair tread shall be not less than thirty inches (30") and not more than forty-two inches (42").
All steps, rails, balustrades, or other guards shall be of sound material and securely fastened.
D.C. Mun. Regs. Tit. 14, § 708