Checking Roof For Hail Damage
HAIL DAMAGE TO ROOF SHINGLES
Figure 3 shows shredded and pock-marked paint from a driving hailstorm. The base wood was undamaged but repainting was required.
Hail damage to asphalt shingles includes severe granule loss, material removal at the edges of the shingles and penetration. Figure 7 shows grit loss from asphalt after pounding from a hailstorm. 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.
In recent years, roof shingle manufacturers have been listing products that conform to Underwriters Laboratories test standard UL 2218, 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. The roofing industry takes issue with some of the testing methods, indicating that shingle aging and thermal environments are not taken into account.
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.