[Greenbuilding] venting vaulted ceiling?

[Reuben Deumling]

I'm remodeling a house that recently had a metal roof installed. The
roofers cut the top 3" of sheeting at both sides of the ridge and stapled
some mesh over the opening and installed vented ridge flashing above. Some
of the attic was already vaulted. I'm expanding the amount that is vaulted.
The tempting and easy thing is to replace those removed strips of plywood,
caulk the seams and insulate from below. But I'm well aware that the
venting beneath roof planes is done with some forethought. I'm keen to
achieve a sealed envelope to keep bugs and drafts out primarily. I've run
across (pictures of) a product that is installed behind/above batts in
rafter bays that allows air to pass between the fiberglass and the
underside of the plywood. Are these still a good idea? Other thoughts on
how I might proceed? What physical phenomenon is the venting meant to
prevent?

Thanks very much.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/greenbuilding_lists.bioenergylists.org/attachments/20140203/12e59042/attachment.html>