N.Y.C. Admin. Code § PC 1110: Section PC 1110: Controlled Flow Roof Drain Systems

1110.1 General.

The roof of a structure shall be designed for the storage of water where the storm drainage system is engineered for controlled flow. The controlled flow roof drain system shall be an engineered system in accordance with this section and Section

28-113.2.2

of the

Administrative Code

. The controlled flow system shall be designed based on the design rainfall rate in accordance with Section 1106.1.

1110.2 Control devices.

The control devices shall be installed so that the rate of discharge of water per minute shall not exceed the values for controlled flow as allowed by the Department of Environmental Protection.

1110.3 Installation.

Runoff control shall be by control devices. Control devices shall be protected by strainers.

1110.4 Minimum number of roof drains.

Not less than two roof drains shall be installed in roof areas 10,000 square feet (929 m

2

) or less and not less than four roof drains shall be installed in roofs over 10,000 square feet (929 m

2

) in area.