Hi all,

I am wanting to build some basic corrugated iron (zincalume) roofs to provide catchments for rainwater collection in a developing country. Does anyone have any suggestions as to ideal roof slopes? The steeper they are I imagine the more expensive, and you are more likely to get splash losses in the gutter, but will probably get better self-cleaning
Thanks!!

I would go with a lower pitch for better water gathering without oversplash instead of trying for a steeper roof that will clean off easier. As such, you need just enough slope so that the roof will drain without leaking. If the roof is sized so that you can get available metal roof pieces that are long enough to run seamless from eve to ridge, then the slope could be as low as 1:12 or even less. If you are collecting the water in a gutter, then you could go up to 6:12 to 8:12 without having too much runoff that could overpower the gutters. If you really want a steeper pitch, then upsizing the gutters will allow you to go even steeper.

Thanks for the advice!!

when i calculate the area of a roof for the size of roof drain piping. i allow 100% for a horizontal wall
draining onto a sloped roof
in other words, a 5ft x 20ft horizontal wall on top of your pitched roof will yield 100 sq ft of rain gathering area. or 200 sq ft if you gather water from both sides of wall. thats a lot of "extra" water
just a thought...frodo

Thanks Frodo. I am confused though as to how you mean the horizontal wall to be - could you possibly attach a quick sketch??
Many thanks!

here is a horizontal wall, picture it on a roof
with the rain hitting it,and running down into your barrels
i am talking about a much smaller wall tho .about 5 ft tall and the length of the roof. this will increase the volume of water collected[URL=[IMG]http://i1357.photobucket.com/albums/q759/41frodos/my%20stuff/internet/th_arch_h_36.jpg[/IMG]]roof[/URL]

This message has been edited. Last edited by: Frodo,