In all districts, the underlying height and setback regulations shall be inapplicable to developments on piers. In lieu thereof, the provisions of this Section shall apply.

The base plane of a pier shall be the elevation of the finished surface of the pier, below which no portion of a building or other structure penetrates, except for the supporting structure, plumbing or utility lines. In the event portions of a pier have different surface elevations, the surface elevation of at least 50 percent of the pier shall be used to establish the base plane.

The height of all buildings or other structures on piers shall be measured from the base plane. For buildings with pitched roofs, maximum building height shall be measured to the midpoint of such pitched roof.

The obstructions permitted pursuant to Sections 23-62, 24-51, 33-42 or 43-42 shall apply. In addition, a dormer may penetrate a required setback area above a height of 30 feet provided the aggregate width of dormers on any given building wall does not exceed 50 percent of the width of such building wall.

(a)        Height and setback regulations on piers

The height of a building or other structure on a pier shall not exceed 30 feet. However, where a setback at least 15 feet deep is provided, the maximum height of a building or other structure shall be 40 feet. Such required setback shall be provided at a minimum height of 25 feet and a maximum height of 30 feet, and may be reduced to 10 feet in depth along any portion of the building or other structure fronting on an open area of the pier having a dimension of at least 40 feet measured perpendicular to such fronting portion. In addition, wind energy systems shall be allowed, provided such a system does not exceed a height of 85 feet, as measured from the base plane to the highest point of the wind turbine assembly or, when located above a roof of the building, a height of 55 feet, as measured to the highest point of the wind turbine assembly, whichever is higher.

(b)        Building width and spacing regulations on piers

The maximum length or width of any building or other structure on a pier shall be 200 feet. The provisions of Section 23-70 (MINIMUM REQUIRED DISTANCE BETWEEN TWO OR MORE BUILDINGS ON A SINGLE ZONING LOT) shall be inapplicable on piers. In lieu thereof, the minimum distance on a pier between any two buildings or other structures that do not abut shall be 100 feet. However, such limitations shall not apply to any building or other structure, no portion of which exceeds 30 feet in height.

Permitted obstructions above the base plane within such required open areas between buildings or other structures shall be limited to those allowed above the lowest level of a visual corridor pursuant to Section 62-513 (Permitted obstructions in visual corridors), except that freestanding accessory buildings or other structures shall also be permitted provided they do not exceed a height of 30 feet and a total area, in aggregate, of 900 square feet. A minimum spacing of 15 feet shall be provided between such accessory buildings or other structures and any other building or other structure on the pier.

(c)        Modification of pier bulk regulations

Modification of the regulations of this Section involving the height and setback or width and spacing of buildings or other structures on piers shall only be allowed by special permit of the City Planning Commission pursuant to Section 62-835 (Developments on piers or platforms), 74-711 (Landmark preservation in all districts) or 74-79 (Transfer of Development Rights From Landmark Sites).