One of the biggest misconceptions in the roofing industry is the idea that a metal roof automatically “reflects heat away” from your home simply because it’s metal or contains aluminum.

That sounds good in marketing. But scientifically, it’s incomplete at best — and often misleading.

Here’s what most roofing companies won’t explain. The truth is this: A metal roof may reflect a portion of visible sunlight, but that does not mean it effectively reflects radiant heat once the roof itself becomes hot.

Those are two very different things.

Reflecting LIGHT vs. Reflecting RADIANT HEAT

This distinction matters.

Visible Light Reflection

This is what most “cool roof” marketing is actually talking about. A light-colored roof or reflective roof coating can bounce away some of the sun’s visible light before it gets absorbed. That can help somewhat, but once the roof material heats up, the game changes completely.

Radiant Heat Reflection

Radiant heat is infrared energy — invisible heat radiation emitted by hot surfaces. Once a roof gets hot from the sun, it begins radiating heat downward into the attic and structure below. This is where emissivity becomes critical and this is exactly where most metal roofs fall short. You have to stop that invisible heat from radiating downward into your attic, your insulation, and ultimately your home. 

Why Metal Roofs Still Get Extremely Hot

Go touch a metal roof panel sitting in the sun. It’s hot, right? Very hot!

If the roof were truly “reflecting all the heat away,” it would not be radiating intense heat into the attic space below. 

Here’s the reality: Most painted metal roofs — including many aluminum roofs — have coatings, stone finishes, paint systems, oxidation layers, or textured surfaces that dramatically increase emissivity.

That means once the roof heats up, it becomes an efficient radiator of heat. So while some sunlight may initially reflect off the roof surface, the roof itself still absorbs a tremendous amount of energy and then radiates that heat downward. That radiant heat transfer is what superheats attics.

This Is Why RoofingFoil™ Matters

A true radiant barrier works differently from a roof coating or reflective paint.

RoofingFoil™ is engineered with a low-emissivity aluminum surface specifically designed to reflect radiant heat energy.

Installed beneath a metal roof with an air gap, RoofingFoil™ can reflect up to 97% of radiant heat away from the structure.

That means:

• The hot roof radiates heat downward
• RoofingFoil™ reflects that radiant energy back upward
• Far less heat reaches the roof deck and attic

This is the key difference: The roof may still get hot, but the structure below the roof stays dramatically cooler.

Why an Air Gap Is Critical

Radiant barriers only work when facing an open air space (doesn't have to be vented, but has to be open with nothing there). That’s why batten systems, counter battens, purlins, or furring strips or the natural curves of tile roofing are so effective when paired with RoofingFoil™.

The air gap creates a space where radiant heat can travel — and where the foil can reflect it away before it enters the building. Without that air space, you lose most of the radiant barrier effect.

“But My Roof Is Aluminum…”

This is another area where roofing marketing gets slippery.

Simply containing aluminum does not automatically make a roof a high-performance radiant barrier.

For example:

• Galvalume roofing contains aluminum, zinc, and silicon
• Painted metal roofs have coating systems over the metal
• Stone coated steel roofs have textured finishes and coatings
• Oxidized or weathered surfaces lose reflectivity performance

Many of these materials may reflect some visible light, but they are not low-emissivity radiant barriers like pure aluminum foil surfaces. That’s a massive difference.

A true radiant barrier is specifically engineered to have:

• High reflectivity (RoofingFoil™ is 97% reflective)
• Extremely low emissivity (RoofingFoil™ has an emissivity of 0.03)
• Proper installation facing an air gap (½" minimum air gap recommended)

Those three things together are what block radiant heat transfer effectively.