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Hail 101

During the course of an average year, hail causes more than $1.6 billion worth of damage to residential roofs in the United States. Hailstorms are most frequent in the southern and central plains states, where warm moist air off of the Gulf of Mexico and cold dry air from Canada collide. The combination of the two different air masses spawns violent thunderstorms.

Hail is created when frozen water drops are lifted in turbulent wind regimes during thunderstorms. As the frozen water is driven to the earth at speeds up to 90 mph it has the ability to increase in size and form a hail stone. Hail stones can very in size from pea size (1/4 inch diameter, minimal roof damage), quarter size (1” diameter, moderate roof damage) and golf ball sized (1.5” diameter, severe roof damage).

The two main types of damage caused by a hailstorm to your composition roof is granule loss, exposing the underlying mat, and rupturing the mat of the shingle. Loss of granules will shorten the life expectancy of the roof. Since the granules have been removed by the hail stones the matting is now exposed to the elements. The UV rays from the sun overtime can cause the mat to crack, aversely affecting the water shedding  ability the roof previously had. Rupturing of the mat is the more severe of the two types of hail damage. This is caused by larger hail stones impacting the shingle. When a shingle’s mat has been ruptured the granules are gone and cracking is visual in places where the hail impacted the shingle. This greatly effects the shingles intended to purpose of shedding water.

Any time a shingle loses it’s water shedding ability, whether from granule loss or rupturing of the mat, water can start to deteriorate your roofing system.  Once the water reaches the roof fasteners, causing corrosion, or the butted joints in the roof decking, water will be permitted to enter the building. 

Inspect your roof as soon as possible after any storm or have NTBS, Inc give you a free roof inspection. Often you cannot see roof damage from the ground.

If you would like information on impact resistance shingles click here.