Is there value to radiant sheathing on South/West-facing walls in hot climate?
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| Posted in Energy Efficiency and Durability on
Is there any measurable benefit to installing radiant barrier sheathing panels (7/16″ OSB) on vertical walls with a West or South exposure in a Southeastern climate? Of particular concern is the siding material ( 1/2″ thick fiber cement shakes) which will seemingly act as an unintended heat storage device, continuing to radiate heat into the wall assembly long after sunset.
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Dennis,
You'll only get a benefit from the radiant barrier if the radiant barrier faces an air space. It's fairly easy to create an air space (a rainscreen gap) with vertical furring strips for horizontal siding, but if you are installing shakes, it gets harder. One way is to add vertical furring strips followed by horizontal furring strips -- but that adds thickness and expense to your wall assembly.
All you get from the radiant barrier plus the air space is additional R-value (about R-2 or R-3 with the air space) -- and if you want the R-value, rigid foam is another option (or just better cavity insulation).