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BOX GUTTER AND RAIN WATER HEAD DESIGN TO AS/NZS 3500.3:2015
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Diagramaic shape of Given Data (Not to scale)
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Ah
Av
Ac
LHS
RHS
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=
=
=
=
=
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Area Horiz
Area Vert'l
Area Cment
Left hand
Right hand
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sq.m.
sq.m.
sq.m.
side
side
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Design Storm Intensity (ARI 100)
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I
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=
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mm/hr
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Catchment Areas as shown in the diagram.
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Calculate roof rise areas.
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Roof Slope LHS = 2 deg Therefore |
Av1 |
= |
Ah1*tan(Slope) |
sqm |
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Av1 |
= |
111*tan(2) |
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= |
3.9 |
sqm |
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Roof Slope RHS = 5 deg Therefore |
Av3 |
= |
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sqm |
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Av3
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= |
22*tan(5) |
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= |
1.9 |
sqm |
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Calculate catchment area for each wind direction |
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Ac = Ah + 1/2(Av facing wind - Av causing rain shadow) |
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wind from LHS |
Ac(LHS) |
= |
111+22+0.5*(1.9+22-3.9-11) |
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= |
137.5 |
sq.m |
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wind from RHS |
Ac(RHS) |
= |
111+22+0.5*(3.9+11-1.9-22) |
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= |
128.5 |
sq.m |
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wind from front |
Ac(front) |
= |
111+22+0.5*(20-0) |
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= |
143
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sq.m |
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Worst wind direction is from the front |
Ac |
= |
143 |
sqm. |
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Design Flow
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Q
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=
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I*Ac/3600
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Litres/sec
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=
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330*143/3600 |
Litres/sec
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=
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13.1
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Litres/sec
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Box Gutter Depth |
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From Fig I1 (Interpolating where necessary)
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Using :- Gutter Slope
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1
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in
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and Gutter Width
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W
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=
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mm
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from fig I1 Minimum Gutter Depth
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d
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=
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mm
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Rain Water Head Calculations
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Selected down pipe size
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=
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mm
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From fig I3, Rain water head Depth (Interpolating where necessary)
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=
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mm
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Rain water Head Depth increased to comply with Note 1 Fig I2
(RWH depth to be >= 1.25*DP dia.)
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= |
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mm
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= |
188 |
mm
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From fig I3, Rain water head Length at slope 1:200
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=
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mm
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Rain water Head Length increased to fit the DP 150 +20
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=
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170
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mm
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Rain water Head Width
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=
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300
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mm
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Summary
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Down Pipe Size
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=
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mm
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Box Gutter Width
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=
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mm
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Box gutter minimum Depth
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=
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mm
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Rain Water Head Depth
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=
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mm
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Rain Water Head Length
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=
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170
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mm
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Rain Water Head Width
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=
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mm
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