🌧️ IPC/IBC 100-Yr 1-Hr Rainfall Rate (In/Hr), Primary Drains & Overflow Scuppers

Commercial Roof Drain & Overflow Scupper Calculator

Size commercial flat roof drainage systems under the International Plumbing Code (IPC) and IBC: calculate roof tributary area flow (GPM = 0.0104 x Sq Ft x Rain Rate In/Hr), primary cast iron drain pipe diameters (3" to 8"), secondary emergency overflow open scupper weir widths, and plumbing margins.

1. Project & Operating Inputs

Roof Tributary Drainage Area (Square Feet e.g. 35,000 Sq Ft)

100-Year 1-Hour Design Rainfall Rate (Inches / Hour e.g. 3.5 in/hr)

Customer Bid Price for Drains, Leaders & Scuppers ($)

Cast Iron Drains, Cast Iron Piping, Sheet Metal Scuppers & Labor ($)

2. Financial Breakdown & Yield

IPC COMMERCIAL ROOF DRAIN SIZING

Turnkey Drainage Package Profit

Plumbing / Roofing Margin

0.0%

Gross Revenue / Bill

Total Project CapEx

Operating / Material Cost