Hail Impact Test: 2-inch Steel Ball vs 4 Types of Asphalt Shingles

Colorado gets damaging hail nearly every year, and most homeowners assume every asphalt shingle is basically the same. They are not. The difference between a shingle that shrugs off a hailstone and one that fractures can be the difference between keeping your roof and filing a claim.

So we tested it ourselves. We took four shingles, two of them rated Class 4 and two of them not, and ran them through a Class 4 style impact test to see which ones actually hold up. Here is what the test showed, what Class 4 really means, and how to decide whether it is worth it for your home.

What we tested

We ran four shingles through the test, two that carry a Class 4 rating and two that do not:

Class 4 rated: GAF ArmorShield II and Owens Corning Duration Storm.

Not Class 4: GAF Timberline Natural Shadow and Owens Corning Duration.

Both Class 4 products have technically passed the test on paper. We wanted to see how they actually behaved side by side, and how far apart the non rated shingles really fall.

What is a Class 4 shingle, and what is the steel ball test?

Class 4 is the highest impact resistance rating an asphalt shingle can earn under the UL 2218 standard. To get it, a 2 inch steel ball is dropped from 20 feet onto the shingle, twice in the same spot, and the back of the shingle is then examined for cracks, fractures, or displacement of the mat. If it holds up with no rupture through the back, it passes. A standard shingle does not.

There are two different ways a shingle reaches Class 4, and the difference matters. Some shingles use a mesh or scrim laminated to the back to resist the impact. Others mix an SBS polymer, a kind of synthetic rubber, into the asphalt itself, which makes the whole shingle more flexible so it absorbs a hit rather than cracking. The best performing Class 4 shingles tend to be the SBS modified ones, because the toughness is built into the material, not added on the back.

What the test showed

GAF Timberline Natural Shadow (not Class 4): Fractured, as expected. This is a quality standard architectural shingle, but it is not built to take a Class 4 impact, and the test showed it.

Owens Corning Duration (not Class 4): Also showed damage under the impact. A popular shingle in Colorado, but without a Class 4 rating it is in a different category for hail.

Owens Corning Duration Storm (Class 4): Held up better than the non rated shingles, but it was only marginally better than standard Duration in our test, and noticeably behind the SBS modified option.

GAF ArmorShield II (Class 4, SBS modified): The clear standout. The SBS rubber gave it real flexibility, the impacts were shallow, and we could not fracture the back even under hard pressure. This is the shingle we most often recommend for Colorado homes.

Our takeaway: if you are going Class 4, an SBS modified shingle like ArmorShield II is where the real protection is. Paying to step up from standard Duration to Duration Storm did not show a difference worth much in our test.

Does Class 4 matter on the Front Range? A real story

During the 2023 hailstorm that hit Erie, Frederick, Firestone, Longmont, and the surrounding northern Front Range, we had a homeowner with a rental in Frederick who had spent roughly a $2,000 upgrade to go Class 4. After the storm, nearly every neighboring roof was damaged. Hers did not have a single impact through the shingle. With a high deductible, she never had to file a claim, and she came out thousands of dollars ahead.

That is the real value of Class 4 in hail country. It is less about a small insurance discount and more about avoiding the next deductible, the next claim, and the next re-roof entirely.

Class 4 and your insurance

Historically, carriers including State Farm, Farmers, Allstate, and USAA have offered premium discounts for Class 4 roofs. Those incentives are changing heading into 2026, and with deductibles now often running several thousand dollars, the bigger financial benefit is often avoiding a claim altogether rather than the discount itself. Ask your agent two things: whether they still offer a Class 4 discount, and how a Class 4 roof affects your deductible and claim history.

Where Class 4 is required by code in Colorado

Some Front Range jurisdictions now require Class 4 shingles by code. As of this writing that includes Fort Collins, Lafayette, Loveland, and unincorporated Boulder County, among others. Areas like Denver, Northglenn, Westminster, and Thornton do not currently require it.

So, is Class 4 worth it?

For most homes on the Front Range and in the foothills, where hail is a near annual event, a Class 4 roof is one of the better value upgrades you can make, especially an SBS modified shingle. It costs more up front, typically a modest percentage over a standard architectural roof, but it can pay for itself by avoiding a single hail claim and the deductible that comes with it. If you are well outside hail country or on a tight budget, a quality standard shingle may still be reasonable. The honest answer depends on your roof, your area, and your risk.

Frequently asked questions

What is a Class 4 shingle?

A Class 4 shingle has earned the highest impact resistance rating under the UL 2218 standard. It survives a 2 inch steel ball dropped from 20 feet, twice in the same spot, without fracturing through the back. It is the most hail resistant category of asphalt shingle.

What is the difference between ArmorShield II and Duration Storm?

Both are Class 4. GAF ArmorShield II is SBS modified, meaning a synthetic rubber is mixed into the asphalt for flexibility, which is where the real impact resistance comes from. In our test it clearly outperformed Duration Storm, which was only marginally better than standard Duration.

Are Class 4 shingles required in Colorado?

In some jurisdictions, yes. Fort Collins, Lafayette, Loveland, and unincorporated Boulder County are among the areas that currently require Class 4, while places like Denver do not. Codes change, so confirm with your local building department.

Will a Class 4 roof lower my insurance?

It may. Several carriers have offered Class 4 discounts, though those incentives are shifting in 2026. Often the bigger benefit is avoiding a future hail claim and deductible. Ask your agent how it affects both your premium and your deductible.

How much more does a Class 4 roof cost?

Impact resistant shingles generally run a modest percentage more than standard architectural shingles. On most Colorado homes, avoiding a single hail claim can offset that difference. You can see how shingle choice fits into the full picture in our Colorado roof replacement cost guide.

Are Class 4 shingles guaranteed not to be damaged by hail?

No. No shingle is hail proof, and Class 4 products are generally not warranted against hail damage. They are significantly more resistant, which is a real risk reduction, but not a guarantee.

Get a straight answer on your roof

WestPro Home Exteriors is a GAF Master Elite roofing contractor based in Longmont, serving Boulder, Denver, Fort Collins, Loveland, Estes Park, and the entire Front Range. If you want to know whether your current roof can take a hailstorm, or whether a Class 4 upgrade makes sense for your home, we offer a free inspection. We will get on the roof, check for storm and hail damage, and give you a straight answer, whether or not that ends in a project with us.