I need to scratch build a small factory building of the brick walls, Crittall windows and flat roof type, and I'm confident about all aspects of the build except for one - the roof.    I know my Google-fu is not strong, but even so I've now tried for over an hour to find a photo of such a roof so I can work out roughly how high the parapet needs to be and how the drainage is done, but to no avail.  Can some kind soul please point me at a picture (real thing or model) which will enlight