We were having a discussion (myself and several roofers) about how to approach a roof. I like to approach a roof as a system, ie, look at the roof covering, sheathing, insulation, ventilation, vapour barrier, etc. and see how they work together. Several of the roofers told me I'm being 'way too finicky and said that from their perspective, they were being paid to put on the roof covering, and everything else is someone else's problem. Their perspective is that the insulation and ventilation should be handled by the insulation guy, the sheathing and similar stuff by the structural guy, etc. I'd like some feedback from practising roofers on how you approach these issues.