Where did this idea come from? We're not sure; perhaps it's due to people's experience with being inside pole buildings or barns that have metal roofs. Chances are those un-insulated structures could be hot on warm days, but the fault isn't in the roof; it's the structure itself. Or perhaps it's because people believe metal itself absorbs heat. Cast iron pans on the stove, right? But that's an erroneous comparison.In reality, metal roofing actually reflects heat due to its relatively low thermal mass. The technical reason is that metal has a low thermal mass, and the lower the mass, the less heat absorption. (If you're really interested in the science behind this, check out this explanation on thermal mass. High thermal mass is a good thing if you're looking to store heat, such as in solar generated. Not so good of a thing in terms of roofing, though.)
Another reality is that metal roofing reflects rather than absorbs the sun's rays, and certain colors are even more effective at it than others. Metal roofing - especially the light colors - is considered a 'cool' roof.One thing you should understand is that a properly constructed home should not have much heat gain or loss due to the type of roofing. (This does not apply to attic space; however. That's a different issue, and one more related to ventilation and insulation than the roofing.) Where heat absorption by roofing material matters is in terms of durability. Certain materials such as asphalt shingles and tile roofing DO absorb more heat than metal roofing. What that means is the roofing will break down prematurely and you'll need a roof replacement sooner.
Got more questions about metal roofing? We've got answers. Check out the basics of residential metal roofing on our page here, or contact us for a free consultation to find out more about how a metal roof could protect your home for your lifetime.Quarve Contracting, Inc./Metal Roofing & Siding of Minnesota is a licensed home improvement contractor serving the greater Twin Cities metro area with exterior home solutions such as roofing, siding, and energy-efficient replacement windows.
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