Re: roof ventilation
I think you have a few options. With the age of the roof, it's just about to its end anyway, so you may want to consider reroofing, especially if it's already showing signs of its age. If you go this route, you can strip the existing roof and then pull the deck sheathing up along the soffits to move insulation and install baffles to existing soffit intakes. or install those intakes if none exist now.
Without reroofing, then the installation of surface intake venting would suffice unless you are in a snow zone where such a vent would not work.
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