How hot weather affects commercial roofs

When the idea of weather damage and roofs are brought together, most people think of windstorms, snow, hail and ice, even torrential rain. Little thought is given to commercial roofing systems when the weather is calm and dry, like it is over summer. 

But heat can do damage too. The extremes of the heat dome have passed, however the long-range forecast for Vancouver this July and August looks to be hotter than normal. Plus there’s always the danger of another extreme heat event like we just had.

Just how does heat affect a roof? A lot of it has to do with thermal expansion and contraction. As the sun bears down during the day, roofing material heats up and expands. At night the air cools and the roof contracts. 

This small shift in movement is more forgiving on newer roofs when the materials are at peak flexibility. With older commercial roofing systems, materials are drier and more brittle. This leaves them prone to cracking and fissuring.

Thermal shifting affects roof seams and fasteners too, causing the former to split and the latter to shear out of place. A sudden rain can also cause a thermal shift on a hot day. (Green roofs don’t experience these shifts as the vegetative layer resists temperature fluctuations.)

UV rays damage flat roofs as well, causing deterioration of the surface. Blistering and bubbling occur when cracks or holes in the roof have admitted water, which expands under the heat of the sun. Different layers of the roof will separate under the stress and pressure.

Hot weather can do different types of damage to flat and low-slope roofs. The best way to minimize this is through regular maintenance and inspections by a professional. Keep small problems from becoming big problems. If you haven’t had an inspection since the heat dome, talk to a commercial roofing contractor in Vancouver today. Schedule an appointment for a checkup of your roof.