Catchment Area No 111 Job No 007
Building xyz Date 1/1/2016
Design: AJB
OVERFLOW DESIGN FOR EAVES GUTTERS to AS/NZS 3500.3:2015
Industrial building for J. Blogs
Blogs Lane - Blogsville.
Catchment area A = 100 sq.m
Intensity ARI 100 I = 333 mm/hr
Coefficient of Runoff I = 1
Roof Slope S = 22 deg.
Roof Slope Factor Sf = 1 + 0.5*tan(Roof Slope)
= 1.2
Design Catchment Area = Sf * A
= 120
Roof runoff = Overflow required Q = C*I*A/3600 L/s
= 1 * 333 * 120/3600
Therefore total Overflow required = 11.1 L/s
Length of eaves gutter = 11 m
Therefore Oflow/metre of gutter = 1.01 L/s/m

### Overflow Methods:

 Manufacturers stated slot capacity
= 0.5 L/s/m
Oveflow to be taken over the gutter. = 0.51 L/s/m
 Determine the setdown "h" from AS/NZS 3500.3 Table G1 (Interpolating as required.)
Is the gutter sloping or level? = Sloping
Therefore h = 15 mm
Is the roof sheeting turned down into the gutter? = yes
From Table G1 Notes: If Roof sheeting is turned down into the gutter. The overflow height may be reduced by about 8mm. Therefore h = 7 mm
"h" < 10 therefore adopt minimum h = 10 mm