Rain Water Down Pipe

Thursday, January 12, 2006

GUTTER CAPACITY CALCULATION
Input roof catchment size for one outlet (m) 8.4m width 34.3m lenght
Roof Catchment Area(m2) 289m2
8.4m x 34.3m = 288.12m2 per RWDP

Rainfall Intensity (mm/hr) (Malaysia) 325mm/hr
Total cross section area of gutter 65790mm2

Gutter width based on structural design/site condition 300mm

Min Average gutter height including 25mm freeboard 245mm
(between lowest & highest point)

Gutter gradient 1:200
Minimum gutter girth (mm) For 1.0mm thick Zincalume gutter 814mm
Minimum gutter size = 300mm(W) x 300mm (D) 900mm

CAPACITY FOR EAVE GUTTER
Downpipe Capacity for Eave Gutter
Cross section of RWDP for EAVE gutter = 95mm2 x Roof Catchment
Based on above roof catchment,
The requierd cross section of RWDP 27455 mm2
Min Recommendation diameter for RWDP = 200mm

CAPACITY FOR INTERNAL BOX GUTTER
Cross section of RWDP for Internal Box gutter = 95mm2 x Roof Catchment
Based on above roof catchment,
The requierd cross section of RWDP 27455 mm2
Min Recommendation diameter for RWDP = 200mm

Maybe you would find the above calculations useful.

5 comments:

Anonymous said...

HI, thanks for your calculation, although it's a bit complicated, I just want to know the minimum size.. thanx

Anonymous said...

Architecture - Occupancy Load auto-calculator here :

http://archi2u.blogspot.com/

aLittleMisfit said...

can show in more detail?
such as how u get the figure or formula explained?

Young said...

Hi,

There are several determining factors for the rainwater catchment:
1. Rain Volume
2. Roof Area
3. Gutter Gradient

You can reference to
http://www.roof-gutter-design.com.au/boxgrwhvf/boxg2calc.html

Anonymous said...

in the "Cross section of RWDP for EAVE gutter = 95mm2 x Roof Catchment" formula, can you please explain where did you get the 95mm2 value?

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