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Posted by McElroy Metal ● Sep 12, 2023 8:00 AM

Do Metal Roofs Make a Home Hotter in the Summer?


Energy efficiency plays a crucial role in the increasing appeal of metal roofing. Numerous metal roofing options incorporate reflective coatings that redirect sunlight, reduce heat absorption, and maintain cooler indoor environment. This reduces dependence on air conditioning in hot months, potentially leading to lower energy consumption and subsequent cost savings for homeowners.

Residence Stillman Valley, ILThe question, “Do Metal Roofs Make a Home Hotter in the Summer?” focuses on whether a metal roof absorbs more heat than a non-metal roof, increasing warmth within the underlying house. Several characteristics come into play:

  1. Low Thermal Mass: Metal roofs are made of materials with low thermal mass, meaning they don’t store and retain heat as effectively as slate or concrete, with higher thermal mass. This characteristic allows metal roofs to respond quickly to changes in temperature.
  1. Reflectivity: Metal roofs are often reflective, which means they can bounce back a significant portion of the sunlight that hits them. This reflection helps reduce the heat the roof absorbs and subsequently transfers into the building’s interior. The reflective property can contribute to keeping the building cooler and more energy-efficient, especially in hot climates. 
  1. Heat Absorption: Asphalt shingles, on the other hand, can absorb a significant amount of heat from the sun due to their higher thermal mass. Asphalt roofs are constructed using petroleum asphalt and mineral granules; these dense, black substances tend to absorb more solar heat. During the summer, bare metal might reach temperatures around 145 degrees, whereas black asphalt shingles can soar to 168 degrees. This absorbed heat can slowly radiate into the building, potentially increasing indoor temperatures and the need for air conditioning.
  2. Cool Roof Effect: Because of their reflective properties, metal roofs are often considered part of the “cool roof” Cool roofs are designed to reflect more sunlight and absorb less heat than standard roofs. This can lead to energy savings and increased comfort inside the building.
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How Metal Roofs Reflect Solar Radiation

A metal roof designed for coolness, boasting high solar reflectiveness and elevated thermal emittance, exhibits a lower surface temperature when compared to a roof characterized by low reflectance and emittance levels. In the context of such a cool metal roof, a reduced surface temperature leads to reduced heat uptake within the space beneath the roof, whether it's the attic or the living area. This outcome results in a more pleasantly cool living environment and decreases energy consumption for heating and cooling purposes. Research findings indicate that a building’s owner can reduce cooling expenses and qualify for money-saving utilities by opting for a cool metal roof.

Colors and Coatings

The color and coating on a metal roof can significantly affect how much heat it absorbs. Providing a range of high-quality coating systems, like Kynar 500®, is of the utmost importance to McElroy Metal. In order to offer the best possible performance options, we partner with Sherwin Williams®, a distinguished industry leader in coil coatings, to serve as our designated coatings manufacturer. It should be noted that lighter colors are more effective in reflection and energy savings than dark colors. However, it’s important to mention that even dark metal is a better choice when compared to shingles.

Insulation Materials

While color and coatings contribute to a roof's heat, insulation can help protect the roof and the occupied space. Insulation also reduces noise during heavy rain, hail, and extreme wind. Insulation with vapor barriers decreases moisture and a number of common roofing problems. When it comes to insulation for metal roofs, there are a number of options available, like fiberglass batts, rigid foam board, and spray foam insulation. Asphalt roofs are constructed using petroleum asphalt and mineral granules; these dense black substances tend to absorb more solar heat. During the summer, bare metal reaches temperatures around 145 degrees, whereas black asphalt shingles can soar to 168 degrees.

Conclusion

So, do metal roofs make a home hotter in the summer? The answer is no. When exposed to sunlight, both metal and asphalt roofs conduct heat to the underlying structure, although the heat conducted by metal roofs is greatly diminished, at a 25-40% reduction.

At its core, a metal roof, when improved with reflective coatings, can feel cooler in contrast to untreated metal surfaces. The improved coolness doesn’t stem from its insulating traits but rather its capability to redirect heat away from the home. As a result, it aids in sustaining a more comfortable indoor setting.

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Learn everything you need to know about Residential Metal Roofing. Check out our metal roofing resources for inspiration and answers to your questions.

About McElroy Metal

Since 1963, McElroy Metal has served the construction industry with quality products and excellent customer service. The employee-owned components manufacturer is headquartered in Bossier City, La., and has 14 manufacturing facilities across the United States. Quality, service and performance have been the cornerstone of McElroy Metal’s business philosophy and have contributed to the success of the company through the years. As a preferred service provider, these values will continue to be at the forefront of McElroy Metal’s model along with a strong focus on the customer.

Topics: Metal Roofing, FAQ, Residential

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