First, some background:

My home was built in 1950. The roof pitch is 6/12. It has roughly 6″ soffits that are not vented. It has a few “turtle” roof vents near the ridge. There is some white mold on the rafters/sheathing in the attic, but the structure seems very straight/square/flat. It also needs a new roof within the next few years, so I’m thinking about how to fix the attic ventilation.

I also need to air seal and insulate the attic. There isn’t enough room near the eaves to blow in as much cellulose as the rest of the attic, so I’ve been thinking about how to use rigid foam (due to spray foam cost and global warming potential) in a Tetris-like fashion to maximize R-value near the eaves.

This morning, I walked by a neighbor’s house and I noticed they had one of those roof edge vents, but it was installed a few rows up from the drip edge. A light bulb went off… this would allow me to reclaim that 1″ of ventilation space near the eaves, which would give another R-6 in that area (using polyiso). I could completely fill the eaves with insulation, and then have the intake vents installed above the top of the loose cellulose.

I’m in zone 4C (Portland OR) and we only get a light dusting of snow less than once a year that melts very shortly thereafter. Ice damming shouldn’t be a concern. Are there any other downsides to this roof venting approach? It looks a little unconventional, but it’s very low profile, so I don’t think it looks bad.

Here’s a link to the manufacturer’s information page: DCi SmartVent Mid-roof installation