What rainfall rates are the “Horizontal Roof Drainage Piping” Programs based on?
The “Rainfall Rate for 100 Year, 60 Minute Duration Storm in Local Area (Inches/Hour)” should be based on the Local Weather Bureau Data, from Locally Adopted Building Codes, or from publications such as National Oceanic and Atmospheric Administration (NOAA). If State or Local Codes require a more conservative sizing basis than the 100 Year, 60 Minute Storm, the required Rainfall Rate can also be used with these Programs. Any Rainfall Rate can be used with these Programs, since the calculations are based on formulas, not on specific charts of various rainfall rates.
