Nick Pine wrote:
marson wrote:

where I'm from, Duluth, MN, the airspace is required by code.

IIRC, ERVs are also code, and a big waste of money.

I think it is important to use a chute the entire length, not only because
it ensures airflow, but it also reduces "windwash" which strips heat away
from your insulation.

"Chutes" encourage "windwash," no? I suggest that you
ignore the code and take control of your own life.

Nick

no, chutes don't encourage windwash because the chutes keep the cold
air from the insulation. it's easy to say "take control of your own
life" but when a building inspector is standing there telling you you
must have vent space period, what are you going to do? we have had
trouble getting hot roofs with 12" of icynene by our building
department, let alone fiberglass.

ironically, i basically agree with you. if i was building my own house
and i didn't have to deal with inspectors, i wouldn't vent the roof
either...but i would also be very anal retentive about my vapor
barrier. in practice, cathedral ceilings do fail (condensation raining
in the house), and unless someone is there who really knows what they
are doing, the safe bet is to ventilate.