Do you need a radiant barrier in the attic if you have a silver galv-alum or white metal roof?

These roofs are excellent reflectors of solar reflectance when new but over-time, as they age and get dirty, the reflectivity is lowered. Radiant barriers would still reduce whatever heat flow that penetrates the roof surfaces by the same percentage - there is just less heat coming through these types of metal roofing materials vs. a shingle roof. As the metal roof ages, and the metal reflects less solar radiation, the radiant barrier has a greater impact on energy savings.

Product Reference: 

FSK Shield
Radiant Shield

Professionals Reference: 

Builder
Insulation Contractor
Building Owner
Architect

Product Applications Reference: 

Roofs
Roofs
Roofs
Roofs
Roofs

Building Type Reference: 

Metal

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