I've got a 24x52 lean to on my pole shed that I want to better insulate the ceiling. Has parallel trusses about 2' deep @ 8' OC w/ 2x4 purlins on top, with R11 or R13 kraft faced inbetween the purlins. Walls are 2x6 and insulated. So the ceiling needs major attention if I don't want to go broke heating the place. Just looking for opinions. My FIL suggested nailing 2" poly foam to the bottom of the purlins and calling it a day. I don't think that's near enough R value. I'm central MN with R49-60 recommended in house attics. Next winter I absolutely will be heating both sides of the shop and realize the benefit of spending money up front to save on natural gas later. This past spring I got significant condensation on the slab so....how to improve ventilation??? I'm redoing all the steel on the building come spring due to hail and am just starting to get this insulation/venting situation plan started. I've searched around and every thread I found is with standard trusses.
