A ten-minute hailstorm in Phoenix can do thousands of dollars in damage to an asphalt shingle roof. Even clay and concrete roof tiles can crack from the impact of falling hailstones. Clues though can be almost microscopic.

An October 5, 2010 hailstorm pounded over 150,000 homes around greater Phoenix. Three-inch diameter hailstones were reported by NOAA in west Chandler.

Evidence of that storm is still showing up during home inspections for real estate transactions several years after the event.

In the August 2016 photo above, several small dents cover the surface of a roof box vent from a home in central Mesa near the Temple Historic District.

Roof box vents are a good first indication site for hail damage. Most box vents are made from aluminum or plastic which reveals hailstone impact through denting or cracking. If you find confirmation, look closely at the condition of the roof surface for more damage.

Asphalt shingles damaged by hail will have small, dime-sized indentions. On these spots where the granular shingle surface has worn slightly, the asphalt-coated mat underneath may be exposed. Clay and concrete tiles can exhibit hairline cracking or chipping.

If your home was built instead with gable vents or a ridge roof vent, the second area to look for hail damage is gutters, then downspouts. An aluminum gutter will be dented from the inside out giving a reverse-dimple appearance when you sight down its length. Also examine the metal chimney cap and aluminum step flashing at the base of the chimney stack.

If aluminum box vents or gutters are dented, it doesn’t automatically mean that this roof is damaged. Box vents can be reused by roofing contractors who are installing a new roof. However, damage to these initial sites is a clue to look more closely. Inspect the shingles and roofing tiles for cracking, pitting or degranulation caused by hail.

Below is a video of the same October 2010 hail storm captured by a homeowner in the Arrowhead Lakes subdivision in Glendale, Arizona.

Hail Storm in Phoenix, Arizona - Oct. 5th, 2010

(You are especially eagle-eyed if you noticed that the two shingles in the lower left of the photo above are improperly face-nailed. They puncture the surface of the roof and allow an entry point for water. The box vent flashing should have been nailed under the shingle.)

Was your Phoenix home damaged in a hail storm? Leave me a comment below. I am interested dating and locating these storms.


The time to repair the roof is when the sun is shining. – John F. Kennedy, the 35th President of the United States