Roof shingles curl when the heat beneath the roof decking becomes hotter than the top surface of the shingle. The shingle soaks up the heat and transfers the heat to the attic or inside of the building causing a heat buildup. It is not unusual to see un-insulated attics reach well above 130 degrees.
Similarly, roof shingles can “pop” from excessive heat. Heat can cause gases to release from the asphalt in the shingles, resulting in a gas buildup in the shingle and forming a “blister”. When the pressure gets high enough, the blister can “pop” and leave a pockmark in the shingle. Although this may look from a distance like hail damage, there is no bruising beneath the pock.
Asphalt shingle nails can also “pop” from excessive heating and cooling, allowing a direct route through your shingle to the inside of the roofing envelope.
These problems can be avoided by using spray foam insulation in your attic space. Spray foam is by far the most energy efficient system of any insulation product available. Keeping your attic insulated from the heat of your house and the isolated from the outer temperature will prevent temperatures from rising and damaging shingles and your roofing envelope.
Some buildings have their HVAC units in the attic so keeping that space regulated will also prolong the health of your HVAC unit.