How can I tell if there is hail damage to a roof?  If there has been a hailstorm in your area, a close inspection of the roof will determine if the shingles have been damaged. Generally you cannot tell from the ground.   What does hail damage look like?

When hail hits a shingle a "bruise" appears that looks like a dark area where the grains or granules of the shingle have been knocked off and the base of the shingle is exposed. Recent hail impacts have a shiny look because the base material has been freshly exposed, eventually the "bruised" area will become weathered. 

How does this damage affect my roof? Hail damage to asphalt shingles includes severe granule loss, material removal at the edges of the shingles and penetration. New asphalt shingles are more resistant to hail impact than older shingles since the asphalt becomes more brittle with age. Warmer shingles are more compliant and more resistant to fracture from hail when compared with colder shingles. Shingles rely on a structurally sound substrate for hail damage resistance. Flexible roof sheathing allows the shingles to flex during impact causing damage, while more rigid roof sheathing supports the shingle during impact resulting in less shingle damage. 

 Most hail related damage is cosmetic and does not affect the useful life of roof shingles. In other cases severe wood splitting, significant granule loss, penetration of the shingle and fracture may require shingle replacement.

 Assessing hail damage is often accomplished by a roof inspection, which usually occurs several days to several months after the hail event. Determination of whether hail actually fell at a site can be made through statements and weather reports. Inspection of thin, aluminum fixtures helps verify hail impact.  Denting of a roof vent caps might indicate that hail had struck the vent at one time.  The denting on these caps does not usually impede their function.

 However deformation to air conditioner condensing unit fins can result from a driving hailstorm. This type damage may impair operation of the unit, in that air flow through the coils is reduced, causing higher refrigerant temperature, lost performance and lost reliability.

In recent years, roof shingle manufacturers have been listing products that conform to an Underwriters Laboratories test which classifies the resistance of a particular product to hail damage. The test entails dropping steel balls on samples and observing the damage. A Class 4 rating is the most resistive to hail damage, while the Class 1 rating is the least resistive. Some insurance companies are reducing premiums when Class 4 shingles are used

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