,The perils of using corrugated iron roofing on low pitched roofs…Corrugated roofing is a great material on traditional pitched roofs – but it has severe limitations when the pitch gets below 5 degrees. That is why all roofing manufacturers recommend the 5 degree pitch as the minimum slope and they will not provide any guarantees if it is installed flatter than this.

http://theroofingprofessionalswestside.com.au/corrugated-iron-roofing-roof-pitch-problems/,