DOWNPIPE AND EAVES GUTTER CALCULATOR

Convert mm to inches or visa versa.
(Rounded to nearest)
Fill in one, click in the other.

mm
inches

 Convert square metres to square feet or visa versa.
(Rounded to nearest)
Fill in one, click in the other.

sq. metres
sq. feet
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Job Description :
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The above fields are optional, and are only necessary if you want this data to appear on the results printout. The 'Header text' field will appear at the top of the print out, and the 'footer text' will appear at the bottom of the print out e.g. Your/Company name, Ph.No., etc.
This information is not stored or used in any other way, and dissapears when you exit this page.
Eaves Gutters:
For sizing eaves gutters, the most efficient (and desirable) cross section, is width = twice the depth.
The plumbing code assumes this in these calculaions, so don't vary too much from this criteria.
The width and depth values shown above are rounded up to the nearest 5mm, and are shown only
to give an idea of the size of the gutter. Pick a standard gutter that is close to these dimensions.
Downpipes:
Check the number of DP's required, if the figure is say 0.1, then that DP is only 1/10 full.
You will be guilty of gross overdesign if you use this. A smaller DP should be used.
If you have the case of say, 3.25 number * 150 dia DP's required, then you may choose to split the catchments to have 3*150 & 1*100 dia DP's. However, it is normally better to keep all DP's the same size and accept 4 * 150 DP's.
Rectangular Downpipes:
Previous design guidelines, and pipe flow formulas, state that a rectangular pipe will not carry as much water as a circular pipe of the same cross secional area. However the code assumes the reverse by a factor of approx 1.23 times area.
Mannings Formula for pipe flow is Q=A/n R^2/3 S^1/2. where R is the hydraulic radius. and is Area/Perimeter. Working through this, you will find that a rectangular pipe is approx 10% less efficient. This used to be the suggested increase in area. However this only applies to a pipe flowing full.
We can only assume that the code writers have conducted experiments and have arrived at the correct answer.
The previous page gives the Code's conversion equivalent from circular to rectangular.
Further notes on the printout:
In the 'Header & Footer text' field, if you wish to enter multiple lines eg. an address, use the break characters <br> to seperate the lines.
If however you really want to print this screen, use the printscreen key, which should copy it to the clipboard, then paste into a suitable program to edit and print.