Why is hail so damaging
Factor #1 – Impact Energy
Hail varies in size, hardness, and velocity, creating Kinetic Energy (measured in Joules), more commonly referred to as impact energy. Impact energy grows exponentially as hail stones grow in size (See Chart below). Note that the impact energy of a 2” hail stone is over 22 times greater than that of a 1” hail stone. Wind assisted hail can further increase impact energy.
Factor #2 – Shape of the hail stone:
The shape of each hail stone also significantly affects the amount of damage inflicted on building components. Irregular shaped hail stones, with spike like appendages, point load Kinetic energy at impact, increasing their damaging effects.
Factor #3 – Attributes of the impacted roof:
Roofs vary in their resistance to hail damage as a result of one or more of the following factors:
- Type of roof
- Quality of materials
- Protective covering (coatings, granules, gravel, etc)
- Age of roof
- Temperature of roof at time of impact
- Density of insulation directly beneath roof
For building owners and insurers alike, roofs typically represent the single greatest risk of loss from hail.