Class 4 roofing decoded: two tests, the fine print and the Texas credit

Where the classes come from

UL says it worked with industry and insurance companies in the 1990s to develop and publish UL 2218, the Standard for Impact Resistance of Prepared Roof Covering Materials. Certified products carry the UL Mark and appear in UL's Product iQ certification database, and the standard yields four ratings, Class 1 through Class 4 (UL Solutions). FM Approvals publishes a separate standard, FM 4473, for rigid roofing such as tile, which also uses four classes (FM Approvals).

How a UL 2218 test is run

The Insurance Institute for Business and Home Safety summarizes the method in its report on UL 2218 impact tests:

Each ball is dropped from the height needed to match the kinetic energy of a hailstone the same size. In IBHS's UL 2218 testing, shingles were installed on 3-foot-square panels following the manufacturer's guidelines, and each chosen spot took two strikes. Any tear, fracture, crack or rupture visible on the back of the shingle is a failure. Crushed or dislodged granules, dents, and openings visible only on the top are not counted as failures under UL 2218.

How an FM 4473 test is run

FM 4473 is written for rigid roofing materials, tiles or planks made from materials such as slate, concrete or clay. Instead of steel, it uses ice balls cast from distilled water and frozen for at least 48 hours, fired from a launcher at speeds that produce set kinetic energies. For Class 4, that is a 2-inch ice ball at a target of 26.81 foot-pounds. Each target spot is hit twice, within half an inch, and targets include edges, corners, unsupported areas, overlaps and joints. A specimen passes if it shows no visible cracking or breakage.

FM explains its choice of projectile: ice balls are generally harder and denser than real hailstones, so they stand in for a worst-case stone. It also says that meeting FM 4473 does not by itself qualify a product for FM Approval, and that the packaging and product must carry the FM Approvals name and hail classification.

The fine print a Class 4 rating leaves out

• Looks. UL 2218 judges breaches seen from the back of the shingle, and UL acknowledges it does not account for the denting or granule loss a homeowner or insurance adjuster can see (UL Solutions). IBHS has since developed a separate rating protocol for those surface effects, which requires UL 2218 certification as a starting point.
• Insurer judgment. IBHS cautions that UL 2218's pass or fail criteria do not necessarily match the criteria insurers use to decide whether to repair or replace a hail-damaged roof (IBHS).
• Age. FM notes that long exposure to the elements can significantly lower a covering's hail resistance, and its standard tests only new material (FM Approvals).
• Stone size. Both tests top out at 2 inches, and North Texas has recorded stones close to three times that, such as the 5.9-inch Sanger hailstone of 2023 (NCEI event 1109306).
• Wind. For wind resistance on asphalt shingles, the Texas Department of Insurance refers to ASTM D 3161 Class F or ASTM D 7158 Class H, which are separate ratings.

The Texas insurance side

TDI's page on impact-resistant roofing credits says eligible materials can take the form of shingles, tiles, shakes, formed metal panels or sheets, provided they were tested at a laboratory under a recognized standard. A Class 4 covering receives the highest premium credit, but each insurer sets the discount for each class and decides which tests, labels and paperwork it accepts.

TWIA is more specific. For its credit, the material must be classified under UL 2218, and since January 1, 1999 the manufacturer's label must show a UL label or one from another TDI-approved lab, the impact class, the manufacturer's name, the year of manufacture and the brand. TDI warns that products without that labeling do not qualify for the TWIA credit even if they meet the standard.

After installation, the roofer fills out TDI's form PC068, certifying the UL 2218 class installed. The form tells homeowners to keep the original and send a copy to their insurer, and says it is not a warranty by the manufacturer, supplier or installer. TDI's home insurance guide points to HelpInsure.com for comparing which discounts companies offer.

Five questions to ask before you pay for Class 4

1. Which standard and which class, and will the wrapper show it?
2. Does my insurer offer a credit for that class, and what paperwork does it want?
3. What wind rating does the product carry?
4. Will the roof deck be inspected, and is any decking replacement written into the contract?
5. Will the installation follow the manufacturer's printed instructions, as TDI's repair guidance requires for shingles?

The National Roofing Directory's encyclopedia entries on Class 4 impact-resistant shingles and on why roof claims get denied cover the product and the claim in more depth.

Frequently asked questions

Does a Class 4 rating mean a roof will survive any hailstorm?

No. Class 4 means the product withstood 2-inch impacts in a laboratory; UL 2218 does not rate cosmetic damage (UL Solutions), and FM 4473 tests only new material. NOAA's Storm Events Database logs 1,986 Texas hail events of 2 inches or larger from 2016 through 2025.

Can metal or tile roofs get impact-resistant credits in Texas?

They can be eligible. TDI's roofing discounts page lists tiles, shakes and formed metal panels or sheets alongside shingles, provided the material was tested at a laboratory to a recognized standard. Each insurer decides the credit.

What is TDI form PC068?

It is the Impact-Resistant Roofing Installation Form, on which the roofing company certifies the UL 2218 class it installed (TDI form PC068). TWIA requires it for its credit, and private insurers may use it or their own form.