06/22/2025
Advantages of Class 4 Roofing Shingles
Class 4 roofing shingles are a premium shingle product and may cost more than standard, non-impact resistant shingles. However, due to the beneficial qualities of these high impact shingles, the initial expense may be worthwhile if you live in a region that frequently experiences hail and windstorms.
Class 4 impact-resistant shingles may:
Eliminate the need for, or reduce the frequency of, roof repairs. Enhanced protection can mean less damage and potentially fewer unexpected repair expenses.
Extend the lifespan of your roof. Your shingles are your roof’s first line of defense. A roof with intact, undamaged shingles is better protected season after season.
Be required to meet local building codes: Due to the frequency of hailstorms, some regional and local governments have established code requirements for Class 3 or 4 rated impact resistant shingles, especially for new installations.
You may save you money on homeowner’s insurance and premiums. Many insurance companies offer discounts for homeowners who use Class 4-rated shingles. Contact your insurance provider to learn more.
Impact-Resistant Shingles: Strength and Durability by Design
Non-impact resistant roofing shingles may be more easily damaged when struck by hail or other debris during a storm.
Therefore, industry-leading roofing manufacturers have engineered asphalt shingles that can help withstand greater impacts and potentially reduce the amount of roof damage caused by storms and hail. Thanks to advancements in shingle design and construction, homeowners can have more protection from hail events and less risk of a costly roof damage claim.
Impact-resistant shingles are commonly engineered in two ways:
A reinforcing, polymer-based mesh is added to the back of a standard asphalt shingle. This mesh is embedded into the asphalt to strengthen the shingle and help reduce cracking when impacted by a hailstone or other debris.
Rubber-like polymers, such as SBS (styrene-butadiene-styrene), can also be added to the asphalt composition to make a shingle more impact-resistant. Integrating the SBS polymer blend with the asphalt produces a rubberizing effect, creating a shingle that is more flexible than standard shingles and more capable of recovering from hail impact.
How Do Roofing Shingles Qualify for a UL 2218 Class 4 Rating?
Back in the mid-1990s, after a series of catastrophic hailstorms across the U.S., the roofing industry developed a test to evaluate their products’ resistance to impact. This standardized test, also known as the Underwriters Laboratory 2218 (UL 2218), is nicknamed “the steel ball test.” This test is now one of the most common used to test and rate the impact resistance of asphalt shingles. Based on the results of this test, UL assigns one of four ratings to a shingle, with Class 4 being the highest possible rating.
During this testing method, a steel ball is dropped from a specified height onto an installed roofing shingle several times. The shingle is then turned over and inspected for any breaks or cracks that could potentially allow water to leak through.
To receive a Class 4 rating, a roofing shingle must withstand having a 2-inch steel ball dropped multiple times from a height of 20 feet. To give you an idea of how strong the shingle must be — if this same test is repeated on a 4-inch concrete paver, the force of the steel ball could crack the paver in half.
While Class 4 is the highest rating for impact resistance, there are also lower ratings a shingle can receive, such as Class 3 and Class 2. The difference between the ratings is that Class 3 shingles withstand a smaller steel ball dropped from a lower height, and likewise for Class 2.
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Q: Are impact-resistant shingles worth the extra cost?
A: When considering which type of shingles to purchase, carefully weigh the long-term benefits of Class 4 shingles vs. the extra expense of a premium product. Don’t forget to factor insurance discounts, local building regulations and your region’s risk of severe weather into your calculations.
Q: What are examples of an impact-resistant roof?
A: Choosing Class 4 rated shingles designed specifically for impact resistant can improve your roof’s likeliness to withstand wind debris and hailstorms.
Owens Corning Roofing offers several asphalt shingles with a Class 4 rating for impact resistance:
TruDefinition® Duration FLEX®: These SBS modified asphalt shingles. Are made with a proprietary blend of SBS polymer modified asphalt. The rubberizing effect of the uniquely blended SBS modified asphalt makes the shingle pliable and gives them greater flexibility and enhanced durability and toughness, especially under intense storm conditions.
TruDefinition® Duration STORM®: Backed with a polymer-based mesh, these shingles are designed to perform better against storms and resist cracking upon impact.
ImpactRidge® Hip and Ridge Shingles: These SBS, polymer modified hip and ridge shingles are rated Class 4 and pair with both Duration FLEX® and Duration STORM®.
Both TruDefinition Duration FLEX® and TruDefinition Duration STORM® feature our patented SureNail® Technology, which helps prevent nail blow-through and pull-through.
