Metal roofs have a host of advantages including durability, flexibility in design, high weight to strength ratio, and fast and easy installation process. Additionally, repairs on Phoenix metal roofs are infrequent — as they can last for 50+ years. Overall costs of metal roofs are also lower than other types of roofing materials.
In warm areas like Arizona, people get the impression that metal is the least suitable material for roofing. Considering how metal heats up when exposed to heat, it is easy to assume and apply that analogy to the whole house.
In reality, metal roofs are best suited for houses in warm areas like Arizona. Tin, copper, aluminum, and steel, all of which are normally heat conductors, are most commonly used for metal roofing.
So, how does metal roofing cool the house?
Metals do not absorb heat. Unlike other roofing alternatives that absorb heat like asphalt slate, concrete, or wood, metals reflects light and heat.
In traditional roofing, the absorbed heat eventually creeps down from the roof to the interior of the house; as a result it takes a long time for the absorbed heat to cool down. Notice how a concrete wall is warm in the evening after a hot afternoon. As metals have less thermal mass, it does not retain heat for long. This can save you more than 20% in cooling costs on a hot day.
Light colored metals are more favored because they can better reflect the heat of the sun away from the house. The latest metal roofing technology infuses reflectors in the metal roof coating making even dark colored metal roofs effective in warding off the heat of the sun.
The Science of Cooling Arizona Houses with Metal Roofs and Ventilation
A tin, steel, aluminum, or copper roof will work best in warm places if the roof construction integrates a good ventilation system. Allowing air to circulate between the heated metal roof and the ceiling will prevent the heat from seeping into the interior of the house.
It is important for the ventilation system to include intakes and exhausts. Intake of air through eave soffit vents can efficiently provide cool air to the underside of roof decks, while ridge vent exhausts compliment the natural and continual airflow.
Ventilation is also essential in keeping the house comfortable during cooler months. As metal roofs do not absorb and keep heat, heating up the house can be a challenge, and expensive. However, with proper ventilation that insulates the living areas from the roof, can alleviate the cold and your heating expense.