Section 1105. Roof Drains

1105.1 to 1105.2 {As in IPC}

1105.3 Primary Roof Drainage.

1105.3.1 General.

Roof area of buildings must be drained into a storm drain by roof drains, unless gutters and downspouts or other non-plumbing drainage is provided. The location and sizing of roof drains and gutters must be coordinated with the structural design and slope of the roof.

1105.3.2 Sizing.

Unless otherwise required by the Code Official, roof drains, gutters, vertical conductors or leaders, and horizontal storm drains for primary drainage must be sized based on a storm of 60 minutes duration and 100-year return period.

1105.3.3 Discharge.

No water from any building may be discharged so as to flow over any sidewalk, footway, or adjoining property, except from window sills, copings, or cornices that project no more than 1 foot (305 mm).

Exceptions:

1. Roofs, cornices, copings, or other similar projections that are less than 5 feet (3.03 m), measured horizontally in the line of flow, as long the water is not discharged on any sidewalk, footway, or adjoining property.

2. Awnings or marquees that discharge off the outer edge.

1105.4 Methods of roof drainage.

1105.4.1 Method 1.

Drainage may be discharged by piping to a storm drain, to the street or alley, or to an approved water course. The installation of piping, connections to storm drains, etc., must be made in accordance with this Code.

1105.4.2 Method 2.

Drainage may be discharged not less than 10 feet (3.05 m) from the building, from other buildings, or from any adjacent property line, as long as the discharge is in a manner that does not allow drainage to cross adjacent property lines or sidewalks.

1105.5 Individual Downspouts.

Gutters of buildings on adjoining properties may not be connected with common downspouts or leaders, but each building must have individual downspouts or leaders on its own property. If a building is more than 4 stories or 50 feet (15.24 m) high, its leader and downspouts must be inside the building's exterior walls.