earlybirds
Well-known member
Here's what I have: 30x40x12 pole barn, trusses are 7 1/2feet apart,2x4 purlins 16" apart set on edge on top of trusses. Trusses have standard 4/12 pitch. Roofing metal sheets are nailed directly on top of purlins. Roof has full length ridge vent, and the metal roofing sheets are ribbed so there are also openings at the bottom of each sheet at the soffit.
Currently, I only heat the shop when I am using it with a torpedo style heater to get it up to 50 or 60 degrees.
Currently, there is NO insulation anywhere in the building. I NEED to change that! Putting in a ceiling at the bottom chord of truss height is out of the question because my lighting, air hose reels, AC cord reels, etc. are in the way. Besides, I want a more open feeling in my shop.
I am going to start by insulating the roof. I have researched this topic extensively, and have found some conflicting information. One article says to just use R13 fiberglass insulation with foil facing stapled between the purlins which would put the 3 1/2" thick fiberglass up against the metal roof. The only space left for air circulation would be the ribs in the metal. Other articles say to not use fiberglass because it will draw moisture from condensation making it useless.
Other articles talk about attaching ridgid insulation to the bottom side of the truss top chord. This would provide space for air circulation and hopefully eliminate roof condensation. 2" of polyiso ridgid board would give me R13.
I also researched the thin Prodex roll type foil insulation, but came to realize that it's more used to block radiant heat in southern US. This wouldn't work well in our long Iowa winters.
How would you advise insulating this roof?
Currently, I only heat the shop when I am using it with a torpedo style heater to get it up to 50 or 60 degrees.
Currently, there is NO insulation anywhere in the building. I NEED to change that! Putting in a ceiling at the bottom chord of truss height is out of the question because my lighting, air hose reels, AC cord reels, etc. are in the way. Besides, I want a more open feeling in my shop.
I am going to start by insulating the roof. I have researched this topic extensively, and have found some conflicting information. One article says to just use R13 fiberglass insulation with foil facing stapled between the purlins which would put the 3 1/2" thick fiberglass up against the metal roof. The only space left for air circulation would be the ribs in the metal. Other articles say to not use fiberglass because it will draw moisture from condensation making it useless.
Other articles talk about attaching ridgid insulation to the bottom side of the truss top chord. This would provide space for air circulation and hopefully eliminate roof condensation. 2" of polyiso ridgid board would give me R13.
I also researched the thin Prodex roll type foil insulation, but came to realize that it's more used to block radiant heat in southern US. This wouldn't work well in our long Iowa winters.
How would you advise insulating this roof?