I live in a 100+ year old home, that by all accounts, has never had any kind of ventilation in the attic. The problem now is we have a modern roof with modern airtight materials and the attic is hotter than the blazes of hell in the summer. Adding to the confusion, we have no insulation in this very large attic but we do have barnboard floors and some old knob and tube in the ceilings below so we can't just blow in some insulation (at this point).

So my question is... if we do install a ridge vent to save on cooling and extend the life of our roof, will we be significantly adding to our heating costs in the winter? Is there a better venting system that allows for seasonal use? For instance, open in the summer but, closed in the winter? BTW, we have never had issues with ice dams, rot, or mildew.

Thanks in advance for the advice.