i am planning a new barn, anticipating a standard raised seam metal roof. 2x4 purlins over rafters, metal screwed to purlins. no insulation nor vapor barrier on barn roof. absent any heat within the barn that is not in a separately insulated / vapor-barriered structure (like a workshop), should i experience condensation on the barn roof?? thanks!
Guest User
2008-04-26 16:57:09.000000
well, i didn't plan any ventilation other than the large doors (sliding, not sealing) and ridge vents at top. i hadn't planned any overhang for soffit vents -- just enough for gutter. however, since i was going to use raised panels, there would be some vent at overhang by default (unless i sealed the raises).
if i wanted to be sure, could i use that foil/bubble rolls? and if so, would i affix it to the rafters, with 2x4 purlins on top (thus, 1.5" gap between bubble insulation / vapor barrier and metal underside, or would i attach the bubble stuff to the top of the purlins then the metal directly on top (no air gap)?
thanks for any help you can offer!
jt
Guest User
2008-04-27 13:25:36.000000
The determining factors will be how much moisture is generated in the barn (from livestock or other things) and how much ventilation will occur in the barn.
Todd Miller
2008-04-27 08:40:01.000000
A vapor barrier like that could be installed either place.
