you can get paint thats much better than bitumen for the roofs.its a gray colour and got fibres threw it.
cant remember the name right now but will have a look tomorow at work as we have been using it lately and its great for painting all the seems to stop water getting in.with the fibres in it it helps seal any small holes much better.can also be painted on when still wet and the moisture helps the paint cure better.
really good shit.just really messy and a nightmare to ome of anything you get it on