What is Impact Rating? – The Secret to Total Roof Protection

Many people upgrading their roofs think that the only thing they need to consider when choosing a new roof is color. But all roofing is not equal. Besides the differences in material, ranging from asphalt shingles to metal, slate, wood, or rubber, there are also factors like resistance to issues, such as fire, wind, algae, and impacts.

Keep reading to find out what is impact rating.

Impact Rating - What Is It?

When browsing through the different roofing options, you may run across products that list an impact rating. This rating defines the material's ability to withstand impacts from culprits like hail, falling tree branches, and storm debris.

Having a roof that can resist damage from impacts can reduce the likelihood of paying for repairs after significant weather. If you live in an area with frequent storms and hail, a roof with a high impact rating is crucial.

Roofs fall into an impact rating classification of four classes - 1 through 4. Classes 1-3 do not generally have impact resistance, offering you the least amount of protection. Class 4 is the highest rating a material can receive, making it the most durable against wind and storm damage.

How is Impact Rating Determined?

Products receive an impact rating based on performance to tests on a scale of one to four.

UL - Underwriters Laboratories - devised testing that rates a material's strength. UL started in 1894 and is a not-for-profit organization that develops safety testing for many products, including roofs.

The UL 2218 Impact Rating-test - also called the steel ball test - consists of dropping four metal balls of varying sizes onto the same spot from various heights at 90 mph speeds, repeated twice. 

If the material shows signs of tears, cracks, or fractures, it receives a failing score of 1, 2, or 3. Examination for damage includes the top material, underneath layers, and back surface. For products that do not damage during these tests, they get the highest score - Class 4. 

The chart below demonstrates the different testing methods and impact rating classifications of the UL 2218 test. As it shows, the larger the steel ball and the higher the distance, the higher the impact rating classification.


Diameter of Steel Ball



1 ¼”

12 feet


1 ½”

15 feet


1 ¾”

17 feet



20 feet

Roofing Material Classifications

Unfortunately, most roofing materials will not have a Class 4 impact rating. If you choose an asphalt shingle with a Class 4 impact rating, you'll see a 10% to 20% increase in price.

To ensure you choose a product that's certified Class 4 rated, look for brands that list UL 2218 Class 4 impact rated, which means the brand went through rigorous testing.

If you see a product listed as Class 4 but does not have the UL 2218 test number, you may end up with an option that did not go through the standard testing and, therefore, may not perform as expected.

What Impact Rating Do I Need?

For many people, there is no need for the enhanced protection of Class 4 impact-rated roofs. However, you should always check with your local building code and state laws, as many places have regulations on what type of roof you can use.

You can also determine which rating you'll need by factoring in your climate. If you live in a dry location with little concern about storms, you could get by with a lower-rated roof.

But if your area suffers from frequent hail storms, tornadoes, or hurricanes, you would have better peace of mind (and better insurance rates) by choosing a Class 4 roof.

Pro Tip: A Class 4 IP does not guarantee higher wind resistance, as wind ratings are a different type of classification, which we explain here.

Also, if you have trees that extend over your roofline, you may want a Class 4 material, despite not having hail or significant weather. Falling tree branches, tree debris, and animals can cause damage to your roof if it has a low impact rating.

If you live in one of the following states, investing in a Class 4 IR roof would be your best option due to the significant hail storms:

  • Kansas
  • South Dakota
  • Texas
  • Colorado
  • Nebraska

Pro Tip: Many insurance companies offer up to 25% discounts on your premium for installing Class 4 Impact Rated shingles.

Best Class 4 Impact Rated Products

All of the major roofing distributors offer Class 4 impact-rated products. Asphalt shingles offer the least protection against impacts compared to more durable materials, although there are multiple lines with Class 4 ratings. Asphalt shingles come in 3-tab, architectural, or designer types. 

Class 4 shingles are primarily in the architectural and designer styles and rarely in 3-tab. These shingles are made in one of two methods to become impact-resistant:

  • A polymer-based mesh coated with asphalt.
  • Rubber-like polymers (SBS - styrene-butadiene-styrene) are blended into the asphalt to create a rubberized effect.

Most metal roofs will have a Class 4 IR (impact resistant), providing the most protection against storm and wind damage.

The list below provides some of the top-rated Impact 4 roofing options.

  • Owens Corning Duration Storm (asphalt shingles)
  • Owens Corning Duration Flex (asphalt shingles)
  • Owens Corning Duration TruDefinition WeatherGuard HP Shingles
  • CertainTeed IR Shingles
  • CertainTeed NorthGate
  • Atlas StormMaster Shake and Slate Shingles
  • Malarkey Legacy Shingles
  • Malarkey Vista Shingles
  • Tamko Heritage IR
  • IKO Nordic Shingles
  • GAF Timberline AS II Shingles
  • Enviroshake Shingles
  • Bartile Concrete Roofing (concrete)
  • DaVinci (synthetic)
  • F-Wave (synthetic)

Pro Tip: In addition to impact and wind ratings, you may also want to find a product that offers algae resistance protection. 

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