What grade of insulation should i use in a WA shop??

I have a 95' x 42' shop. One section is 40'x42' with a 16' ceiling and two 14'x14' roll-ups, The other is 55'x32' with an 11' ceiling and three 10'X10' roll-ups. Then one other 10'x55' section in the back that is not insulated at all. I have R19 in the walls and R38 in the attic. The doors all have weatherstripping and only three inuslated windows in the whole shop. I also sheet rocked, taped and sealed everything before painting. I have a 14,000 BTU oil furnace set up on a thermostat and ducted to each insulated section. During the worst part of winter, the shop never gets below 45, this is with the furnace off. It takes about an hour to raise the temperature to 60 in both sections. It was the best money I ever spent, insulating my shop. Nothing like staying warm and working on your toys while the snow coming down outside. Second best money spent, was on a four post lift. Good luck

 

Thanks guys I already started, on the 12x24 walled off end i'm going R21 and on the other end probably R15 or mabey R19 when I get to it