Last year I built myself a 28x32 pole barn, with metal skin, both on side walls as well as the roof. No insulation was installed at build time due to my tight budget.

Now I'm wishing I had insulated during the build process. I live in Florida, just north of Tampa Bay, so the winters are mild and summers are the killer time for me in the shop. I would like to be able to heat the shop, just to take the chill out of the air. I don't need it roasting hot, just sweatshirt type of comfort.

My walls are of 6x6 corner posts, with 4x6 on 8 centers, 2x4 running verticle, on 24" centers up the wall. Roofing is just the metal skin.

My question is, what is the best, cheapest method of insulating a standing pole barn? I'm not interested in closing the walls up with drywall, nor the ceiling area.

I was thinking of using the rigid poly(?) board insulation for the ceilings, the stuff that has silver coating on both sides, attached with roofing nails, with plastic washers.

How about the walls?

Does this sound OK? or does anybody have any different approaches I should investigate?

Thanks.
Jeff