Do Metal Roofs Make Your House Hotter?
Quick answer
No — the opposite. A metal roof with a Cool Roof-rated reflective finish bounces solar heat away instead of absorbing it like dark asphalt, and metal does not store heat. Interlock's Alunar finish (solar reflectance up to 0.55, emissivity 0.84) helps keep homes cooler and can cut summer cooling costs.
Where the "hot metal" myth comes from
People picture a car left in the sun or a bare metal shed and assume a metal roof must bake the house beneath it. But a home roof is nothing like a shed panel. The intuition also confuses touch-temperature with heat transfer: what matters for your comfort and cooling bill is how much heat reaches your living space, and that depends far more on reflectance, emissivity, ventilation, and insulation than on the roofing material feeling warm on a sunny afternoon.
What actually happens on a metal roof
A Cool Roof-rated metal roof does two helpful things: it reflects a large share of incoming solar energy, and it quickly re-radiates the heat it does absorb rather than storing it. Interlock's Alunar finish reflects up to 0.55 of solar energy depending on color and carries a high 0.84 thermal emissivity across every color. Dark asphalt does the opposite — it absorbs solar heat and holds it, pushing it down into the attic through the afternoon and evening. That is why a reflective metal roof typically results in a cooler attic and lower cooling costs.
How to maximize the cooling benefit
You get the most from a metal roof's reflectivity by pairing it with good attic ventilation and insulation, which carry away and block the heat that does get through. Choosing a higher-reflectance color helps in hot, sunny climates, though every Alunar color is cool-roof capable. Homes with living space directly under the roof and modest insulation see the biggest improvement — exactly the situations where a hot asphalt roof is felt most.
Frequently Asked Questions
Do metal roofs make a house hotter?
No. A Cool Roof-rated metal roof reflects solar heat and sheds what it absorbs, unlike dark asphalt that absorbs and stores heat. Metal roofs typically help keep a home cooler and lower cooling costs.
Are metal roofs hotter than shingles?
No — a reflective metal roof runs cooler in effect than dark asphalt because it reflects more sunlight and does not store heat. The result is usually a cooler attic and lower air-conditioning use.
Do dark metal roofs get too hot?
Darker colors reflect less sunlight, but Interlock's darker Alunar shades still carry a high 0.84 emissivity that sheds heat, and metal doesn't store heat like asphalt — so even dark metal roofs stay cooler than expected.
Do metal roofs save on cooling costs?
Yes, typically. By reflecting solar heat and radiating away what they absorb, cool-roof metal roofs reduce the cooling load, which the U.S. Department of Energy notes can meaningfully lower summer energy bills in warm climates.
Sources
- U.S. Department of Energy — Cool Roofs — Reflective roofing & cooling
- ENERGY STAR Roof Product List — Interlock Alunar values — Reflectance & emissivity
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Last reviewed 2026-07-11 · Reviewed by Scott Plumptree, Director of Marketing