The surprising truth about heat, attics, and the one layer most roofers leave out.

You did everything right. You replaced your old shingles with a beautiful standing-seam metal roof — or maybe went with clay tile, like your neighbors in Florida or Arizona swear by. The salesperson told you it would reflect heat. Lower your bills. Keep your home cooler. And maybe it helped a little. But come July, your upstairs bedrooms are still stifling. Your air conditioner still runs non-stop from noon to midnight. Your electric bill still makes you wince.

You're not imagining things. And your roof isn't broken. The problem is what's under it.

The Real Culprit: Radiant Heat

Here's the physics lesson your energy bill has been trying to teach you. When the sun beats down on your roof — metal, tile, or otherwise — it heats the surface through solar radiation. That heat doesn't just sit there. It radiates downward, warming the roof deck (the wooden sheathing underneath your roofing material). The deck then radiates that heat into your attic. Your attic, now essentially an oven, pushes heat down through your insulation and into your living space.

Think of it like a campfire. You don't have to touch the flames to feel their heat — you feel it from several feet away. That's radiant heat. And it travels right through standard underlayments, right through your fiberglass insulation, and right into the rooms where your family lives.

Even perfect insulation can't stop radiant heat — it only slows it down. In hot climates, attic heat from the roof can account for 30–50% of a home's total summer heat gain.

This is the part that surprises most homeowners: insulation is not a radiant barrier. Insulation works by slowing conductive heat transfer — the kind that moves through solid materials by contact. But radiant heat travels like light, through air, without needing anything to conduct it. That's why you can have a perfectly well-insulated attic and still cook in your top-floor bedroom every summer.

Why Metal and Tile Roofs Aren't Enough on Their Own

Metal and tile roofs are legitimately better than asphalt shingles in hot weather. Metal reflects a significant portion of solar energy, and tile's natural thermal mass helps it resist quick heat transfer. These are real advantages. But here's what the marketing brochure doesn't always mention: even with a reflective metal or tile roof, heat still builds up between the roof surface and the deck below. And once that deck is hot, it radiates heat downward — regardless of what's on top of it.

The standard felt or synthetic underlayment installed under your metal or tile roof? It's doing its job — keeping water out. But it has no ability to block radiant heat. It's essentially invisible to the infrared energy that's making your attic miserable.

How a Radiant Barrier Underlayment Actually Works

A radiant barrier works on a brilliantly simple principle: it reflects radiant heat the same way a mirror reflects light. RoofingFoil™ + Underlayment All-in-One is installed directly on the roof deck before your battens and metal or tile panels go on. Because metal and tile roofs are installed with battens — creating a natural air gap between the roofing material and the deck — there's already a built-in space for the radiant barrier to do its work.

That air gap is the key. For a radiant barrier to be effective, it needs to face an air space. The reflective surface of RoofingFoil™ faces that gap, and when radiant heat comes radiating downward from the hot metal or tile above, it hits the reflective surface and bounces back. It never reaches the deck. It never heats up the attic. The effect inside your attic is dramatic — standing in it on a sunny summer afternoon, it genuinely feels like a cloudy day.

Here's how the layers work together, from top to bottom:

1. Metal or Tile Roof Surface — Gets very hot from direct sun exposure; surface temps can exceed 150°F on a summer day.
2. Air gap (created by the batten system or the natural curvature of the tiles) — This is where the magic happens- the heat from the roof converts into radiant form to cross the air gap.
3. RoofingFoil™ + Underlayment All-in-One Radiant Barrier — The foil reflective surface faces the air gap and reflects (or bounces) 97% of the radiant heat back up before it ever reaches the deck.
4. Roof Deck (Plywood/OSB) — Stays dramatically cooler; barely knows the sun is shining because the foil is keeping it cooler.
5. Attic Space — Temperature stays manageable, not the 140°F+ oven it would be otherwise.
6. Your Living Space — Noticeably cooler rooms, less AC strain, and lower energy bills are all benefits you see immediately.
   
   

The "New Roof" Opportunity You Don't Want to Miss

The absolute best time to install a radiant barrier is during a new roof installation — specifically, right before the battens go down. Once your metal panels or tile are on, retrofitting a radiant barrier under the roof requires removing and reinstalling everything (that's expensive & disruptive) or it requires you to crawl around in the sweltering attic space (if you even have one!). That undoes most of the cost savings.

If you're already planning a new metal or tile roof, adding RoofingFoil™ + Underlayment All-in-One to your project is a relatively small incremental cost with an outsized return. Your roofer rolls it out across the deck, secures it with cap nails or staples, then installs the battens right on top. The whole process adds minimal time to the installation. Compared to the total cost of a premium metal or tile roof, the addition of a radiant barrier underlayment is a fraction of the investment — and it's the piece of the system that actually addresses heat.

RoofingFoil™ + Underlayment All-in-One is also two products in one:

• Acts as a primary/secondary moisture barrier to protect the deck from any water that gets under the metal or tile.
• Reflects up to 97% of radiant heat — U.S. Department of Energy studies show radiant barriers can reduce cooling costs by 17% or more in hot climates!
• Tear- and puncture-resistant layer that is built tough enough for real job site conditions (you can walk on it!).
• Works under metal, standing seam, tile, slate, and any roof with a batten system or natural air space.
• Installs quickly — roll out, cut, nail, done. No special tools or techniques required.
  
  

What About My Existing Insulation?

This is one of the most common questions we hear: "I've already got good attic insulation. Do I still need this?" The answer is almost always yes — and here's why.

Insulation and radiant barriers solve different problems. Your attic insulation slows down (conductive) heat that has already gotten into the attic. A radiant barrier prevents that (radiant) heat from getting into the attic in the first place. These two systems are designed to work together, not compete. When you block radiant heat at the roof level with RoofingFoil™, your existing insulation becomes significantly more effective — because it's no longer fighting against a 150°F attic. The cooler your attic stays, the better your insulation performs, and the less your air conditioner has to compensate.

Think of it this way: if you're trying to keep a room cool, it helps to have good insulation in the walls. But it helps even more if you close the windows first. A radiant barrier closes the window on heat before it ever enters the attic.

The Bottom Line for Homeowners

Metal and tile roofs are excellent choices. They last longer, look better, and perform far better than asphalt shingles in hot weather. But they are not, by themselves, a complete thermal system. They reflect some solar energy from the outside — but without a radiant barrier underneath, they still allow radiant heat to pour into your attic and work its way into your home.

RoofingFoil™ is the missing piece. It's the layer that sits between what the sun is doing up top and what your family is experiencing down below. It's not a miracle — it's straightforward physics. Reflective surfaces stop radiant heat & air gaps make them work. Metal and tile roofs already have the air gap built in. All you need is the reflective layer.

If you're getting a new roof installed, or if your roofer is replacing the underlayment on an existing roof, this is your moment. Ask your contractor about RoofingFoil™ + Underlayment All-in-One. It's a small addition to the project with a big impact on comfort, energy bills, and the life of your HVAC system — for as long as that roof is on your home.

Energy savings estimates based on U.S. Department of Energy radiant barrier studies. Individual results vary by climate, attic configuration, and installation quality.