What is the difference between Class 3 and Class 4 impact-resistant shingles?
Both ratings come from the UL 2218 test, where steel balls are dropped onto a shingle from a set height. A Class 3 shingle survives a 1.75 inch ball without cracking, and a Class 4 shingle survives a 2 inch ball, the highest rating the test gives. Class 4 is the one many Texas insurers discount premiums for, and it is the rating to ask about in a hail-prone area.
The test drops steel balls, and the class is the largest one the shingle survives
UL 2218 fixes a shingle to a roof deck and drops steel balls of increasing size onto the same spot twice. After each drop the back of the shingle is examined for any crack or tear. Class 1 passes a 1.25 inch ball, Class 2 a 1.5 inch ball, Class 3 a 1.75 inch ball and Class 4 a 2 inch ball.
A steel ball is harder than a hailstone and it is dropped straight down, so the test is a controlled comparison between products rather than a promise about any particular storm. Wind-driven hail hits at an angle and at a different speed. The rating tells you how one shingle stacks up against another under the same abuse.
Why Class 4 is the rating most North Texas homeowners ask for
The Dallas and Fort Worth area sits in one of the most hail-active parts of the country, and storms with stones over an inch arrive most springs. A standard architectural shingle can lose enough granules in one of those to shorten its life by years, even when it does not leak.
Class 4 shingles use a rubberized asphalt or a reinforced mat that flexes on impact instead of fracturing. They still get damaged by very large hail, but they shrug off the mid-sized storms that would otherwise send a whole street into insurance claims. Class 4 lines come from Owens Corning, Malarkey, and GAF, and we install all three.
The insurance side: discounts, and what a claim will and will not pay for
Texas insurers are allowed to offer a premium discount for a roof covered with impact-resistant shingles, and many do. The size varies a great deal between carriers and policies, so the only way to know is to ask your agent before you choose a shingle, and to keep the manufacturer paperwork showing the rating once the roof is on.
When hail has already damaged a roof and the claim is approved, the policy normally pays to replace like with like. Moving up to a Class 4 shingle may cost the difference, or your carrier may treat it differently, depending on the policy. Ask before signing, and weigh the upgrade cost against a few years of discounted premiums.
Related questions
Do Class 4 shingles look different?
Most Class 4 lines come in the same architectural profiles and colors as standard shingles, so from the street they look the same.
Is Class 3 worth it if Class 4 costs more?
Class 3 is a real step up from a standard shingle, but Class 4 is the rating insurers usually tie discounts to. Price both with the discount your carrier quotes before deciding.
