Impact-Resistant (Class 4) Shingles: What the Rating Means and What It Doesn’t

A Class 4 label means a sample of the shingle earned the top class of the UL 2218 test, in which steel balls up to 2 inches across are dropped onto its most vulnerable points. It does not make a roof hail-proof, and the two manufacturer documents quoted below both exclude hail damage from the shingle warranty.

Whether Class 4 pays off for your house depends on three things you can check in writing: how often damaging hail reaches your county, how the specific product scores in independent hail testing, and what your insurer will commit to on paper. If you are still choosing between materials, start with how roofing materials compare and come back here once asphalt shingles are on the shortlist.

What a Class 4 Label Certifies Under UL 2218

UL 2218 is the Standard for Impact Resistance of Prepared Roof Covering Materials. UL’s catalog lists UL 2218 Edition 2 with an edition date of November 29, 2022 and a revision date of May 28, 2024, and describes the test as steel-ball impacts aimed at locations on the test assembly where the product is most vulnerable.

The class tells you the largest steel ball the sample withstood. According to the IBHS summary of UL 2218 impact tests (August 2014), the projectile is 1.25 inches in diameter for Class 1, 1.50 inches for Class 2, 1.75 inches for Class 3 and 2.00 inches for Class 4. Class 4 is the highest class and Class 1 the lowest.

Drop height ranges from 12 to 20 feet depending on the class, according to a 2022 Asphalt Magazine article on roof impact testing. One shingle manufacturer’s brochure describes its Class 4 test as a 2-inch steel ball dropped from 20 feet and its Class 3 test as a 1.75-inch ball from 17 feet. Treat those heights as that manufacturer’s description of the procedure, not as a figure printed on your product.

What to verify on your quote: the label or data sheet should name the standard (UL 2218), the class number and the exact product line. “Impact resistant” with no standard and no class is a marketing phrase, not a rating.

UL 2218 vs. FM 4473: Steel Balls and Ice Balls

Some product sheets list a second rating from FM Approvals. The ANSI/FM 4473 standard fires freezer ice balls instead of dropping steel balls, with the same four ball sizes: 1-1/4 inches for Class 1 up to 2 inches for Class 4. The edition on FM’s site is ANSI/FM 4473-2011, reaffirmed October 10, 2020, and its scope is new prepared rigid roofing materials, with slate, concrete and clay tile among the examples. Some shingle makers still publish FM 4473 classes for their shingles anyway.

FM also maintains a separate standard for steep-slope roof covers, FM 4475, which FM updated on September 21, 2022 to add Very Severe Hail testing using a modified FM 4473 procedure with a 2-inch ice ball.

Neither source publishes a conversion between the two sets of classes. A shingle can carry a UL class, an FM class, both or neither, so compare products on the same standard.

What the Rating Does Not Prove About Real Hail

UL’s own catalog summary of the standard notes that no direct correlation between steel-ball impacts and hailstone impacts has been established. That is the core limit: a steel ball has one density, one shape and one path straight down. Hail varies in all three, arrives at angles when wind drives it, and lands on a roof that has spent years in sun and heat, not on a fresh sample on test day.

Size is the one variable you can look up for your own area. NOAA’s National Severe Storms Laboratory treats hail quarter size (1 inch) or larger as severe, so the 1-inch mark, not the 2-inch test ball, is the line that matters when you read your county’s storm record later in this guide.

Impact-resistant products also differ from one another. In its fourth edition of ratings, released November 19, 2025, the Insurance Institute for Business and Home Safety (IBHS) evaluated 24 impact-resistant shingle products. Most earned “Good,” none earned “Excellent,” and IBHS states that if a product rates Marginal or Poor, it does not recommend using it in areas that experience hail. The IBHS ratings are one published test that separates the products they cover.

After a storm, judge the roof by what it shows, not by its label; what hail damage looks like on shingles covers the signs.

Who Pays When Hail Damages a Class 4 Roof

Not the shingle manufacturer, under the two manufacturer documents quoted below; read the exclusions in your own shingle warranty to confirm. One manufacturer’s impact resistance data sheet for its Class 4 line (January 2026) states that hail damage is specifically excluded from coverage under its warranty, and a second manufacturer’s impact-resistance brochure says hail damage is not covered under its limited warranty. A Class 4 label is a test result, not a hail warranty.

That leaves your homeowners policy, on its own terms. Some policies limit or exclude hail damage that changes only the roof’s appearance; how that wording works is covered in what homeowners insurance covers on a roof.

Three documents decide who pays on your house:

1. The declarations page, which shows your deductible and whether wind or hail carries a separate deductible.
2. Any endorsement that mentions roof surfaces, roof coverings or cosmetic damage.
3. The shingle warranty itself, read for its hail clause before you sign the roofing contract.

Is Class 4 Worth It Where You Live?

Value comes from two sources: a premium credit, if your insurer offers one in writing, and the hail losses you avoid paying yourself. Weigh both against the price difference between a Class 4 quote and a standard-shingle quote for the same roof:

value = (written annual credit x years you expect to own the house) + (your out-of-pocket cost per hail loss x expected hail losses in those years) minus the price difference between the two quotes

Each input has a place to come from. The credit comes only from your insurer’s written answer; if it offers none, the first term is zero. How credits are filed and documented is covered in roof-related insurance discounts. Out-of-pocket cost per loss starts with the deductible on your declarations page and grows if an endorsement excludes appearance-only damage. The price difference comes from two quotes on the same roof.

Expected losses come from local history. NOAA’s Storm Events Database holds the records behind the official Storm Data publication, with data from January 1950 to May 2026 as of November 2026, so the newest months lag behind. Periods of record differ by event type, and county filtering works only when you search a single state. Use a look-back window at least as long as the years you expect to stay, and count the years in it with hail of 1 inch or larger reported in your county; checking storm history for your address walks through the search and what the records do and do not prove.

Hypothetical example: with no written credit, a $2,000 out-of-pocket cost per loss, one expected loss over the years you plan to stay, and a $3,000 price difference, value = $0 + ($2,000 x 1) minus $3,000 = negative $1,000. These inputs are invented to show the arithmetic, not typical prices. Change any one with a written number and the answer can flip.

Read the second term as a ceiling. It assumes the Class 4 roof avoids the loss entirely, which no rating guarantees.

One exception sets a higher bar than the formula. If you want an IBHS FORTIFIED Roof designation, its Hail Supplement requires shingles rated Good or Excellent on the IBHS hail ratings, which is stricter than a UL 2218 Class 4 label alone.

Should You Pay for Class 4 Shingles?

Pay for Class 4 when all three conditions hold: your county logged hail of 1 inch or larger in more than one year of your look-back window, the exact product rates Good or better in the IBHS ratings, and the formula turns positive using numbers you have in writing. If any condition fails, the Class 4 premium is buying a lab class, not a measurable return. The hail-history condition is this guide’s screening rule, not a published threshold: 1 inch is the size the Storm Prediction Center’s frequently asked questions use to define severe hail, and more than one year in your window is a simple way to separate a pattern from a single storm. Use it as one input beside the insurer’s written answer and the real price difference, not as proof that Class 4 will pay for itself.

Before you sign, send three questions in writing:

1. To your insurer: “Would a UL 2218 Class 4 roof, or one rated Good by IBHS, change my premium or my roof-surface coverage? Please state the credit and the endorsement by name.”
2. To each roofer: “Name the product, its UL 2218 class and its IBHS rating on the quote.”
3. To each roofer: “Show me the warranty’s hail clause.”

File the answers with the quotes, and plug the written numbers into the formula above.

This guide is general information for U.S. homeowners, not legal, insurance, tax, or engineering advice. Codes, laws, and policy terms vary by location and change over time; confirm details with your local building department, your insurer, or a licensed professional.

Sources

• UL 2218 Standard for Impact Resistance of Prepared Roof Covering Materials, UL Standards & Engagement
• Relative Impact Resistance of Asphalt Shingles: Summary of UL 2218 Impact Tests, Insurance Institute for Business & Home Safety
• ANSI/FM 4473 Impact Resistance Testing of Rigid Roofing Materials by Impacting with Freezer Ice Balls, FM Approvals
• IBHS releases its most expansive impact-resistant shingle ratings to date, Insurance Institute for Business & Home Safety
• Duration Series Shingles: Impact Resistance Testing and Classification, Owens Corning
• Storm Events Database, NOAA National Centers for Environmental Information
• Storm Prediction Center Frequently Asked Questions, NOAA Storm Prediction Center