my friends 28 x40 addtion in mich. has a contin ridge vent but no soffit just 1x fascia adn gutter to match existing. so how do we get "soffit" vents with no soffit? (hardie board siding) also will one gable vent work instead(only one side available due to other end sits on garage roof). also i understnad the code is 1:300....or 3.7 sf of vent with 60% of that low...correct? or is thta just at the top with twice as much at "soffit". ps at this point I think he's just going with the gable vent(and ridge)...no "soffit" vents at all....is that an issue? we did look into the drip edge vents, but didnt check out the free air that gave us. i think he rejected that idea...thanks nice show.