WSRCA Issues Information Bulletin 2017 S-2 Regarding Gutters & Drainage

The bulletin relates to steep-slope roof drainage and specifically gutters and downspouts.

As the severity of surface weather storms appear to be occurring with greater frequency and in some areas with increased amounts of rainfall, WSRCA’s Steep-slope Committee wants to remind roofing designers, roofing contractors, and all of our members of the importance for appropriate roof system storm water run-off management. This bulletin in particular relates to steep-slope roof drainage and specifically gutters and downspouts.

Within the two primary model building codes that address storm water run-off management for the most of the Western region of the United States (The International Code Council’s [ICC] International Plumbing Code (IPC), and the International Association of Plumbing and Mechanical Officials’ [IAPMO] Uniform Plumbing Code [UPC]), the code requirements vary depending on the adoption of the model code and any amendments that local jurisdictions may have implemented.

In the International Plumbing Code (IPC), Chapter 11 Storm Drainage, published by the ICC, the installation of gutters on steep-slope roofs is not directly dictated or required. As with other model building codes, tables are included to assist with the sizing of gutters and vertical leaders (i.e., downspouts), often based on 100-year storm reoccurrence and 60-minute rainfall data. The most recent and current editions of the IPC do not provide language dictating the installation of gutters. However, the 2015 Uniform Plumbing Code and other previous editions, published by IAPMO, does state that gutters are required within Chapter 11, Storm Drainage. Therefore, it is critical to be aware of the Codes that are in effect in the jurisdiction of your roofing or reroofing project and understand the requirements for storm water run-off management.

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WSRCA Steep-Slope Committee

Stan Robinson - Chairman: Pacific West Roofing

Don Fry - Fry Roofing, Inc.

Everett Martin - Empire Roofing

Steve Nash - Waterproofing Associates

Mike Tory - Tory's Roofing & Waterproofing

Mike Wakerling - General Roofing Company

Jim Carlson - WSRCA Technical Advisor, Building Envelope Technology & Research

Steven Elliott - Assistant Technical Advisor, BET-R