Your box needs to breath too. Houses since the early 1980's are constructed with 100% vented soffit ventilation. When you look up under the overhangs of your house you are looking at the soffit. Houses built before the 80's had plywood soffit and vent grates were installed to allow air to move into the attic space. In attempt to beautify their homes many people have installed vented aluminum or vinyl soffit. This makes the house look a lot cleaner but I have found that in many inspections that the installers of the vented soffit did nothing to increase the air flow to the roof. They should have removed most of the plywood soffit before they installed the new soffit. THe air has to move freely in the attic space to acheive maximum efficiency of your homes ventilation system.
More to come....