Secondary Roof Drain Requirements

A standpipe or dam built within the secondary drain dictates the anticipated water depth.

Secondary roof drain requirements.

Scuppers shall be sized to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by section 1101 7 scuppers shall have an opening dimension of not less than 4 inches 102 mm. Secondary roof drains are to be positioned on the roof so that water will drains to the primary upslope and they should not be installed at the same elevation as the primary. Roof slope of 1 4 per foot minimum is required on all roof systems. This system shall be compliant with all federal state and local codes.

Because of that no certain distance exists. Prior to the 1994 upc the only mention of secondary roof drains is a listing of the materials to be utilized for over flow drains in the 1994 upc rainwater systems was included as appendix d to the code. The rationale for not requiring secondary drainage is that if positive drainage is provided that is adequate to drain the roof. As we will see in steps 3 4 the size of the roof drain lines is dependent on the square feet of the roof area being served by each roof drain.

Part a d1 1 d notes that. Exception 1 of section 1511 1 states existing roofs do not have to meet the requirements of the code if positive drainage is provided. In these instances new secondary drain age does not need to be installed if the existing roof system provides for positive drainage. These drains are distinguished by having higher rims.

A secondary roof drain achieves its function by controlling the water build up. Ibc s secondary roof drainage requirement first was added in ibc 2009. When a secondary roof drainage system is installed it shall discharge independent of the primary building storm system and shall terminate a minimum of 18 above grade in an area that will be visible to the people who occupy the building. Slope should be built into the structure on new buildings.

Using ibc 2009 or ibc 2012 it could be inter. This article describes several methods for determining the drainage capacity required to safely drain water off of building roofs whether from rainfall melting snow or a combination of those water sources. Secondary drainage was not required with ibc s previous editions. We describe online roof drainage requirements calculators pertinent plumbing standards a table approach to looking up roof drainage.

Secondary emergency roof drain systems shall be sized in accordance with section 1106 based on the rainfall rate for which the primary system is sized. The uniform plumbing code followed a similar path to incorporating secondary drainage requirements.