I live in N-E QuÃ©bec, and from now till April, forget an unheated shop... I have 20 X 30 feet in the second story of an old barn with a tin roof over rough planks. The roof is at 45 degrees and meets the floor. No side walls. I just have to heat the place up to 50F occasionally. Does anyone have any experience with successfully insulating with LESS R-values than what is suggested, and maybe using other materials besides Pink wool ? How about 2 in of foam and some superfoil with air bubbles and TenTest? Also, to heat, I would like to avoid electricity ($), and wood stoves in such an old building are just like looking for trouble. Maybe a corn furnace with an outside air intake? My only question is wether the circulating fan could get clogged up because of dust? Any suggestions? Merci!!