Question

I'm replacing an asphalt shingle roof in heating-dominated Idaho. My first choice is metal roofing. Is a dark color best for our climate?

Asked by Kristi Appelhans
Idaho Falls, ID

We use no air conditioning in our home and are heating between October and the end of April, sometimes into May. The Energy Star roofing recommendations seem counterproductive for our climate when for most of the year we are looking for heat gain. Does a dark color roof add any significant heat gain in a roof with 12" of fiberglass insulation and a 4/12 pitch? Are there other considerations regarding color and/or material for a cold climate?

Answer

Martin Grohman

Answered by Martin Grohman

Biddeford, ME

GAF Materials Corp

September 30, 2010

Is your attic "conditioned space"? In other words, is the insulation up against the roof?  Or is the insulation on the floor of the attic, and the attic not heated or cooled (more common)?

In this more common non-conditioned case, the most important consideration is actually proper attic ventilation -- ridge and soffit vents that move air through the attic, helping the home to breathe and remove heat in the summer and moisture in the winter.

There's some fairly sophisticated energy modeling to really pin down heat gain vs. cooling (you can try a basic version here) but generally, since you don't have A/C, you might find you like having cool roofing. The argument being the sun is lower in the sky in the winter, and there are more cloudy days in the winter, so the heating effect is not as significant as the offsetting heat reflection from the cool roofing in the summer.

Please consider cool asphalt shingles, which work very well with the ventilation I described. And be sure to inquire about recycling your old asphalt shingles, which are widely used in asphalt pavement. You can learn more at shinglerecycling.org. Idaho does not have a spec for public roads yet, but they can still be used in commercial paving.

Tagged In: roofing, metal roofing

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