R10X districts, and C6-4X districts which have an R10X residential district equivalent, are subject to Quality Housing regulations but instead of a maximum height, the portion of the building above the required setback is subject to tower regulations. A C6-4X district is mapped along Sixth Avenue in Chelsea.

The floor area ratio (FAR)of 10.0 may be increased to 12.0 if affordable housing is provided pursuant to the Inclusionary Housing Program or, for a mixed building, if a public plaza is provided along a narrow street. Public plazas are permitted only in buildings with a commercial or community facility base. The building base must be between 60 and 85 feet high and extend along the entire frontage of a wide street. A tower is permitted above 85 feet provided it is set back at least 10 feet from a wide street and at least 15 feet from a narrow street. To prevent excessively tall and narrow towers, a tower must have a minimum lot coverage of 33%.

Off-street parking is not required.