Useful diagnostic article https://www.metrotile.co.uk/wh....at-are-the-most-comm for anyone dealing with an existing low pitch roof that's performing poorly. Covers ponding, condensation, flashing failures, and insulation deficiencies in a logical sequence with explanations of why each problem occurs. The discussion of minimum pitch requirements and why some materials fail below certain angles helped us understand why our original UPVC membrane roof was problematic. The case for converting to a properly pitched tiled roof using lightweight materials follows naturally from the content.