I know the NHBC is not to everyone's taste. So please bear with me when I link to the NHBC Standards documentation.
I linked to it because, for Know-Nothings like me the illustrations are very helpful.
(accessed May 2018)
For example, I now know what the overlap for my roofing membrane should be. Before now, I didn't know that was an issue I should think about.
I dunno wot I dunno
Full Reference:
http://www.nhbc.co.uk/cms/publish/consumer/Search/?cx=001053047772510740247%3Aogiwepchq-a&cof=FORID%3A11&q=standards&sa=Submit