On April 26, 2016

How Big Does Hail Have To Be To Cause Damage To Your Roof

While the recent hailstorms in Texas have caused damage that is just hard to believe, and has left many homeowners struggling to repair the giant holes in their roofs before the next storm, the truth is not all hail comes in the grapefruit-sized version that the residents of Texas witnessed. Typical hailstorms, as you can imagine are much milder. But does that mean they don’t cause damage?

This was a question that researchers from the Haag Engineering Company recently asked. Wanting to find out just how large a hail ball has to be to cause damage to a roof, researchers used a mechanical device called the IBL-7 (Ice Ball Launcher, 7th generation) to propel ice stones at various types of roofing material. To control the velocity of the ice stone, latex tubing was used to guide the ice stone on a track before being released.

Keeping the velocity constant, researchers tested ice stones from .75 inch to 2 inches in size on the following types of roofing material: 3-tab fiberglass shingles, 3-tab organic shingles; 30 year laminated shingles; cedar shingles; heavy cedar shakes; fiber-cement tiles; flat concrete tiles; S-shaped concrete tiles; and built-up gravel roofing.

The result? As you might expect, there was considerable variation in the impact resistance of different types of roofing material. However, the material most susceptible to damage was the aged 3-tab asphalt shingles. The material that held up the best against impact were the S-shaped concrete tiles and built-up gravel roofs. However, the study also found that the majority of roofing materials tested (5 out of 9) were damaged by an ice stone 1.25 inches in diameter. Further, using additional field observations, researchers were able to isolate the threshold level likely to cause damage based on the size of the ice stone for each roofing material as follows:

3-tab asphalt shingles                                              1.00

30 year laminated shingles                                     1.25

Cedar shingles                                                           1.25

Medium cedar shakes                                              1.50

Fiber cement                                                              1.50

Concrete tiles                                                             1.75

Built-up gravel roofing                                            2.50

While the national weather service issues a severe weather alert when hail is expected to be .75 inch or larger, as the residents of Texas now know, these warnings don’t give time to do the preventative maintenance that might have mitigated some of the damage. One of those prevention strategies is simply to have your roof inspected for damage. Most roofing companies, such as ASAP Roofing, in Aurora, Colorado offer free roof inspections.


Marshall, T., Herzog, R., Morrison, S., Smith, S., (2012) Hail Damage Threshold Sizes For Common Roofing Materials. Haag Engineering Company, Dallas, Texas.

This article is brought to you by ASAP Roofing, a national leader in hail restoration, roofing weatherization, and exceptional customer service. ASAP has offices in Aurora, Colorado, Dallas, Texas, and Indianapolis, Indiana. ASAP also offers free home inspections year-round.

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Contact Us today for Guidance on roof restoration from hail damage.

  • By Joe Carroll  0 Comments 

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