NEED ADVICE ON REPLACING AN OLD LEAKY ROOF
Interesting point about not mixing ridge and gable vents—I hear that a lot, but I’ve actually seen some older homes where a combination worked out fine, provided the attic space was large enough and the intake/exhaust ratio was balanced. It’s definitely not the norm, but sometimes the existing structure just doesn’t allow for a perfect setup, and you have to improvise. Maybe that’s more the exception than the rule, though.
On baffles: they’re a pain, agreed, but I’ve found that if you’re working with a more modern insulation system (like spray foam), you can sometimes skip baffles altogether and still avoid moisture headaches. Depends on your climate zone and how much you’re willing to invest up front.
Totally with you on underlayment—too many people try to cut corners there and regret it later. As for checking around chimneys and valleys... learned that lesson the hard way once when we uncovered a whole ecosystem of rot hiding under what looked like perfectly good decking. Always worth poking around more than you think you need to.