My metal building shop, with garage doors open all the time.
I,m going to add eight inches of fiberglass insulation to the roof and then back that with plywood. To kill some of that summer sun heat. It doesnt matter if its face or not, do I need a vapor barrier
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Replies
Don't put insulation in contact with roof metal, keep it inch or so away, will promote good air circulation above insulation. Vapor barrier can be helpful under insulation, strong winds are a problem to keep out, with this type building.
BB,
FG insulation is not going to help you stay cool no matter where you put it in your building.- Unless you plan on conditioning the space. Your light colred roof helps, but I would give some consideration to using Astrofoil or some other comparable reflective Efoil. The insulation value of the foils is minimal, but keeping the heat out to begin with, more than makes up for it.
They make a bubblewrap with foil 1 side and white on the bottom to be used as a finished side down that would eliminate the plywood ceiling that you spoke of.
You can pin it to the purlins with some 1.5" plastic washers made for that application. Even if you add AC at a later date, I think you are way ahead of the game by using the foil.
I agree with Boats, vapor barrier or not, that FG insulation won't do any good if your door is left open, and the space is not conditioned.
What you want is a reflective surface which ill reduce the emissivity of the sun shining down on the roof. Go wtih the foil bubble wrap product, or something similar.
Justin Fink - FHB Editorial
Your Friendly Neighborhood Moderator
How do you heat the place? If you don't heat it 24/7 in the winter, and it's generally just a few people occupying it for a few hours a day, you don't need a vapor barrier unless there's something in there that puts out a lot of humidity.
IOW, if it's an MJ farm put in the VB, otherwise no need.
They don't call it HYDROponic for nuthin now huh?
Spheramid Enterprises Architectural Woodworks
I have irriatable Vowel syndrome.