🌧️ IPC Table 1106.2 Gravity Roof Drains & Vertical Leaders (Inches/Hr Rain GPM)

Commercial Stormwater Roof Drain Calculator

Size conventional gravity commercial roof drain bodies, overflow scuppers, and vertical stormwater leaders under International Plumbing Code (IPC) Chapter 11: calculate design rainfall intensity flow (GPM = 0.0104 x Rainfall in/hr x Roof Sq Ft), select cast iron leader pipe diameters (4", 6", 8", or 10" pipe), and plumbing contractor profits.

1. Project & Operating Inputs

Total Roof Surface Drainage Area (Square Feet e.g. 65,000 Sq Ft Roof)

100-Year 1-Hour Rainfall Intensity (Inches / Hr e.g. 3.5" per Hour)

Customer Bid Price for Supplied & Piped Roof Drain System ($)

Cast Iron Drains, Cast Iron Hubless Pipe, No-Hub Couplings & Plumbers ($)

2. Financial Breakdown & Yield

IPC CHAPTER 11 ROOF DRAINAGE

Turnkey Roof Drain Package Profit

Commercial Plumbing Margin

0.0%

Gross Revenue / Bill

Total Project CapEx

Operating / Material Cost