Unconditioned Space Insulation


Old 07-12-05, 09:28 AM
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Unconditioned Space Insulation

My garage, which is an unconditioned space, becomes very hot and undesirable to work in during the summer. The attic above the garage is not insulated. The remainder of the attic, over the conditioned living area, has batt fiberglass insulation with the kraft paper facing the ceiling of the rooms. I live in South Florida with high temperature and humidity.

Can I use this same type of insulation over an unconditioned space? Will the insulation help with the heat problem in the garage? Should I keep the paper side of the insulation facing the ceiling of the garage?

Thanks for your help.
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Old 07-23-05, 11:18 AM
Join Date: Jul 2005
Location: Fairway, KS
Posts: 5
Generally, warm, humid climates year round require the vapor barrier on the exterior side of the insulation. This is because the interior usually contains cool dry air and without a vapor barrier, moisture will condense at some point within the thickness of the insulation. Warm air can hold more moisture than cold air. This results in constantly damp, ineffective insulation and mold growth on the back side of the sheetrock and/or exterior siding. As a general rule of thumb, you put the vapor barrier on the warm side of the insulation. In the Midwest, where I live, this rule is kind of a compromise because our winters are cold and dry, but summers are very warm and humid. Typically, we put the vapor barrier on the interior side of the insulation because we have more cool, dry days than warm, humid days. Any moisture that may get into the insulation will evaporate when the weather changes.

In your unconditioned garage, a vapor barrier is not really necessary since there is not a warm and a cool side. The insulation may not help too much with the heat problem in your garage. Insulation only delays heat transfer. What may be more effective is an attic fan that moves the air up and out through the roof or gable vent.
Old 08-03-05, 11:35 PM
Join Date: Sep 2004
Location: Canada
Posts: 71
I understand that SUPER THERM is an approved product in your state for this type of application. A few years back the Florida power company offered rebates if you used this product as it is proven to save energy costs. ST is a thin film multi-ceramic insulation coating. This type of insulation does not load up with heat like the standard bulk insulations. It is more effective in preventing heat transfer. Try an internet search for a distributor in your state.

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