Severe Weather and Your Roof, Part 3: Heat
By J-Conn Roofing, Friday, May 23, 2014
Damaged Shingles

In some ways, your roof is like the top of a solar oven. It receives the full brunt of the sun hitting your house, is your main protection against ultraviolet radiation, and covers the insulated area (attic and eaves) that, by design, trap heat during cooler months. Heat buildup, on your roof and in your attic space, is a major cause of deterioration of standard roofing shingles over the long term.

Your roof and attic have two main defenses against the sun. The first of these defenses is your roof shingles. Standard asphalt shingles have a coating of roofing granules, which provide reflection of the sun’s ultraviolet radiation. Homeowners should periodically check for loss of granules in the gutters and at the exit of the downspouts; excessive granule loss causes shingles to lose some of their protection from ultraviolet radiation.

The second defense against excessive heat is built into your roof: attic and roof venting. If your roof and attic did not have the capacity to ventilate against heat buildup, your roof materials would suffer heat damage from the inside. It also would be difficult to keep your house cool in the summer. There are different types of ventilation such as ridge vent, low profile attic vents, and wind turbines. J-Conn can help you select the option that is best for your home.

There are different factors that determine damage to your roof from heat and ultraviolet radiation:

  • Thermal cycling. If you live in a climate that experiences profound changes (high and low) in daily temperatures, your roof materials will experience greater amounts of contraction and expansion than homes in other climates. Great variations between high heat and cooler nighttime temperatures frequently result in thermal cracking, in which shingles crack or split due to contraction and expansion.
  • Shingle quality. High-quality shingles will have a longer life span than low-quality shingles.
  • Orientation of your house. A roof slope facing south will experience more thermal cycling and greater exposure to ultraviolet radiation during the day.
  • Elevation. If your house is situated at a higher elevation, it receives more exposure to ultraviolet radiation.
  • Slope. Flat roofs undergo more direct exposure to ultraviolet radiation than roofs with steep slopes.
  • Inadequate ventilation. Obstructed or absent ventilation structures are causes of dangerous heat buildup. Excessive attic heat can damage shingles from the inside of the house by causing roof shingles to curl because of heat stress.

As a homeowner you can look for the two major visual indicators of roofs suffering from heat damage: granule loss and split or cracked shingles; however, you should have your roof inspected by a roofing professional.