Insulating a metal shop?

I thought at some time this would come up. I have a 3,000 sq. ft. shop so the roof and upper half of the building I insulated with the manufacture insulation, the lower half of the walls I used a 4 3/8" 4'x8' foam board. the foam board came from a roofing company (in your area) it's the material they use on commercial flat roofs. The owner gave me the material for free because he had a whole building full of it and was going to take it to the dump. So I would suggest calling some roofing co. No I don't remember the name of the company but I drove up to Sac, about a three hour drive and loaded my 8'x16' trailer and my pickup bed as high as I could and brought the material home. I used a table saw to cut the foam, it worked well and made a huge difference in the shop.