Sloopes Roof Drainage

Overview

Engineering reference data for Sloopes Roof Drainage in sanitary drainage.

Key Formulas

Manning's Equation

$Q = \frac{1}{n} A R_h^{2/3} S^{1/2}$

Open channel flow.

Slope

$S = \frac{\Delta h}{L}$

Hydraulic gradient.

Variables

Slope Grades

The following conversions apply to gutter slopes:

• 0.5 % grade = 0.5 cm per 100 cm run = 0.0625 inch per 1 ft run
• 1 % grade = 1 cm per 100 cm run = 0.125 inch per 1 ft run
• 2 % grade = 2 cm per 100 cm run = 0.250 inch per 1 ft run

Downspout Sizing

Match gutter diameter to downspout diameter using this guideline:

• 100 mm (4") gutter → 75 mm (3") downspout
• 125 mm (5") gutter → 100 mm (4") downspout
• 150 mm (6") gutter → 100 mm (4") downspout

Drainage Capacity Table

Interactive Charts

References

• Original Source