Different roof types heat up differently for two main reasons: membrane colors and materials. Lighter roof colors have higher levels of solar reflectivity. That means they reflect more visible light, UV rays, and heat off the membrane than darker colors. Dark colors absorb light and heat, causing the membrane to grow hot. However, membrane materials also absorb light and heat differently. For example, built-up roof (BUR) membranes contain layers of gravel, slag, and reinforcement fabric, and these materials often absorb more heat and light than single-ply TPO and EPDM membranes, which only have one layer. Also, one roof membrane type can come in multiple colors. Some roof membranes, such as EPDM, come in both black and white. White roof vs. black roof temperatures can vary greatly, as can temperature differences between roof materials.
Here’s how hot different flat roof types get in summer weather:
- Black Roof Membranes: 140 to 190 degrees Fahrenheit
- White Roof Membranes: 102 to 120 degrees
- Built-Up Roofs: 125 to 140 degrees
- Green Roofs: Up to 90 degrees
These roofs vary in temperature because of their colors and materials. If you want to keep your commercial building cool during the summer, choose a membrane with light colors and cool materials.