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What the UL 2218 classes actually measure
UL 2218 is an impact-resistance test for roofing materials. In plain words, a steel ball is dropped onto a prepared roof sample, and the material is checked for damage under the test's criteria. The four classifications describe increasingly demanding impacts. Class 4 is the highest classification in that test, not a separate category of indestructible roofing.
The steel ball gives a repeatable laboratory comparison. Real hail is ice, with different shapes, hardness and ways of breaking apart, so laboratory results cannot reproduce every storm. Use the rating to compare tested impact performance, then also consider the roof deck, installation details, ventilation and the material's suitability for your home.
Class 3 versus Class 4
Class 3 uses a smaller steel ball than Class 4 under UL 2218. A Class 3 shingle has tested impact resistance, but it has not met the same impact classification as a Class 4 shingle. If a quote simply says “impact resistant,” ask which classification applies and which test was used rather than assuming it means Class 4.
The newer FM 4473 test uses ice balls instead of steel balls to evaluate impact performance. A product's test designation matters: ask for the actual rating documentation instead of treating every impact-related label as interchangeable. You do not need to become a testing expert, but you should know what the label on your proposed roof means.
Impact resistant does not mean hail proof
Class 4 shingles are designed to resist impact better than a comparable standard shingle without that rating. Large hail can still damage them, and wind-driven debris can strike in ways a laboratory ball drop does not capture. Repeated storms, aging and installation problems can also change how well the roof performs over time.
The rating is not a wind rating, a guarantee against leaks or an insurance promise. It also does not certify every other component on the roof. Flashing, vents and other exposed parts may respond differently from the shingles. A roof is a system, so selecting a stronger shingle does not remove the need for careful installation and inspection after a significant storm.
Why the decision matters around the Metro East
National Weather Service hail climatology indicates that about 73% of significant hail reports, meaning hail 2 inches or larger, in Missouri and Illinois occur from March through June, mostly in the afternoon and early evening. That seasonal pattern gives local homeowners a practical reason to discuss impact resistance before the next replacement rather than waiting until another storm arrives.
National Weather Service storm reports recorded 3 to 3.75-inch hail across parts of Madison County, Illinois, and St. Charles County, Missouri, on March 14, 2024. On May 8, 2024, reports included 2.75-inch hail around Hillsboro and Festus in Jefferson County. These events illustrate local exposure, not how any particular shingle would perform.
On May 16, 2025, reports included 2.5-inch hail around Harvester, Weldon Spring and Cottleville. On April 27, 2026, 2-inch hail was reported in Glen Carbon, Alton, Godfrey and Bethalto; on August 22, 2026, Highland had a 2.5-inch report. Past events are context for a material decision, not a prediction that your home will be hit again.
Ask your insurer about the discount first
Many insurers offer a discount; ask yours, it varies by carrier. That applies to homeowners comparing options in both Illinois and Missouri, but there is no universal discount. Ask your agent or insurer which ratings qualify, whether the roof's age matters and what proof of the installed material they will need.
Get the answer for your policy before you base a purchase on an assumed saving. A contractor's estimate is not confirmation that your insurer will reduce the premium. Keep the rating documentation and installation records, and ask when any change would take effect. Do not compare roofing choices using a discount that has not been confirmed.
Read for cosmetic-damage exclusions
Some insurers attach a cosmetic-damage exclusion to impact-resistant roofs. That can affect how a claim is treated when the roof has visible marks but still performs its water-shedding function. The rating and the exclusion are separate issues: stronger tested impact resistance does not automatically mean broader coverage after a storm.
Ask your insurer to explain whether an exclusion applies, what it covers and how it distinguishes cosmetic from functional damage. Read the actual endorsement rather than relying on a general sales description. For Illinois policyholder and legal detail, see our insurance and roof replacement guide; Missouri rules differ.
Compare the premium in words and scope
Class 4 shingles often involve a modest premium over standard architectural shingles, but the actual difference depends on the material and the work your roof needs. Ask for roof-specific alternatives with the same installation scope. Otherwise, a difference in tear-off, decking work, flashing or ventilation can look like a difference in shingle cost when it is really a different project.
Think about how long you expect to keep the home and whether a confirmed insurance discount changes the comparison. Added impact resistance may matter even without a discount, but it is not a promise that the roof will avoid future repair costs. No general calculation replaces a written estimate and your own policy terms.
Choosing a brand and an installation plan
All major shingle brands offer a Class 4 line, and we install all major brands. There is no single “best Class 4 shingle” for every home. Compare the documented rating, the suitability for your roof and the installation scope. A product name alone does not tell you whether the proposed roof system addresses existing problems.
Do not assume the impact classification describes a manufacturer's warranty. Ask for the specific product documentation separately. An existing roof also needs inspection before anyone decides whether it is a suitable base or requires tear-off; installing a rated shingle over an unsuitable base cannot correct the underlying condition.
For storm assessment rather than product selection, use our hail-damage guide and storm damage roofing page. A Class 4 label should never be a reason to skip an inspection after suspected damage.
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What to do next
Hail Mary Roofing & Exteriors is based in Glen Carbon, Illinois, serving the Metro East and St. Louis area. Request a free roof inspection with a photo report to understand your roof's condition. Call (618) 806-9898; if water is coming in, we offer 24/7 emergency tarping.
Limited Lifetime Craftsmanship Warranty on asphalt shingle roofs, transferable to a new owner one time; 10-year craftsmanship warranty on all other work.