Attic Ventilation - Heating

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Amanda Chambers

September 19, 2023 02:59

What is more important for helping reduce heat in an uninsulated attic? The roof color or the amount (ratio to sf) the attic is ventilated?

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  Kara Zhang September 19, 2023 17:44

  Hello Amanda,

  I don't know the answer. But I think it depends. The climate zone, slope direction. And I think in some local building code, roof ventilation is mandatory.

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  ccronin04 September 21, 2023 14:02 (Edited September 21, 2023 14:34)

  Interestingly - and contrary to popular belief - the purpose of attic ventilation is not to remove heat (although it sometimes does); the purpose is to remove moisture in order to control condensation. Roof color and reflectivity are more reliable ways of reducing attic temperatures. The surface temperature of a dark roof could be something like 220F, whereas the surface temperature of the reflective roof on the building next door could be something like 180F. In other words, it’s a big difference! 
  
  

  Attic ventilation, by contrast, might reduce attic temperature by 3-5 degrees. 
  
  

  These are generalizations to give you an order of magnitude type of comparison. If you’re looking for real research on this, I think Armin Rudd has published work.

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  Russell Forster September 25, 2023 05:26

  Perfect, thanks Christine!

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