Some of the key aspects of BS6229 are interestingly relevant and cover information which we might take for granted at our peril.
Did you know, for example, that a flat roof must have a minimum fall of 1:80 after taking into account roof deflections? When you realise that this is less than 1infinity, it's easy to recognise that this is too shallow.
However, I have seen many roofs casually notated as 1:100, as if by some kind of hangover from a drainage layout rule of thumb.
These problems easily come back to haunt an unsuspecting architect if drawings are left with junior technicians.
Manufacturers confirm that, in tests, fixings puncturing the vapour control layer do not lead to significant air leakage.
Flat roofs are obviously not flat, but the definition extends to roofs with a slope not exceeding 10infinity, although the recommendations apply to roofs 'marginally greater than 10infinity'.