No better time of year to discuss proper attic ventilation than August. I’ve crawled around a few attics this month, and as always, I am amazed at the huge difference in temperature of properly vented attics compared to improperly vented ones. An improperly vented attic can be as much as 50 degrees warmer than an unvented attic. If it is 100° outside, and your attic isn’t vented, it could be 150° up there. This heat load on your home air conditioning is much more than anything you could be losing through non-insulated walls and single-pane windows.