Insulation help for my garage with pics

If your garage is heated, think about using a ceiling fan to pull heat down from the peak. You'd be surprised at the temperature differential with uncirculated air under cathedral ceilings. There is also more heat transfer through a material as the temperature differential increases.

If it is 70 degrees at floor level and 100 degrees at the peak, you would be fighting to maintain 70 degrees for comfort while the roof is bleeding heat. If you mix the air constantly, the peak temperature will be closer to ground-level temperature, say 70 degrees and there would be less energy transfer if it was still 100 degrees up there.