Hello everyone, yes I am a Newbie so thank you for your patience.
I am trying to insulate my cathedral ceilinged garage in order to make it more comfortable to work in here in Southern California. Here are the facts: 2 x 4 construction, 16" on center, no soffit or ridge vents. I had intended to apply Reflectix to the underside of the roof and then fill with basic fiberglass insulation and top off with drywall. However, because of the 2 x 4 construction, there is not enough room for air flow except that I have no soffit or ridge vents to even allow for air flow. So I thought I might buy a Whirlybird to suck out hot air, but these seem to only be for enclosed attics. I also am concerned that my idea may invite moisture to gather underneath the drywall and then subsequently force me to redo everything.