My house (in southeastern Tennessee) was built in the late 1930s, and the roof has no overhang (no soffits). I'm having it re-roofed (stripping off the multiple layers of shingles down to the planking -- from what I can tell, there looks to be 3 layers of shingles, and the lowest level looks like ancient shingles from the 1960s, so yes, definitely in need of re-roofing). Also having gutters and several of the fascia boards replaced, too. The existing venting in my unfinished open attic space consists of 2 "not large" gable vents (one at each end of house). There's never been soffit venting, since there are no soffits.
As part of re-shingling, the plan is to add ridgeline vents. However, since the only intake would be from the gable vents, it doesn't seem to me that there would be sufficient airflow for decent ventilation. I've found information on vented drip edges (which add a lower source of intake air by retrofitting the intersection of the roof and the exterior wall), but I'm troubled by products like the Air Vent that have vents positioned basically over the gutter (and if the gutters are blocked or covered with snow/ice, might allow water to enter, in some instances).
I've discovered another approach, however, with products like the Ever-Flo Inhaler Vents. (Kudos on having a company name and product name that leads to Google results that mostly deal with respiratory ailments.) Here's a link: http://www.everflovent.com/pro_inhaler.html
This Inhaler vent basically goes BEHIND the gutter to feed air into the attic (the air actually enters underneath or below the gutter, as opposed to other vented drip edge designs where the air enters above the gutter). Use of gutter is optional in its use.
Seems like this would solve my ventilation problem. Anyone have experience with this approach or product?