Class 4 Impact-Resistant Shingles: Do They Make Sense in Michigan?

Livingston County has recorded nine confirmed hail events of an inch or larger since 2020, including half-dollar hail in Fowlerville this February and ping-pong-ball hail in Pinckney in 2023. Every one of them was large enough to damage a standard shingle. That is the case for Class 4 in one paragraph. Here is the rest of it.

What Class 4 actually means

The rating comes from UL 2218, a test in which a two-inch steel ball is dropped from 20 feet onto the shingle — twice in the same spot. A Class 4 shingle shows no cracking on the back of the mat afterward. Class 3 passes the same test with a smaller ball. A standard architectural shingle has no rating at all. The steel ball is roughly the impact of two-inch hail, which is larger than anything Livingston County has recorded in this decade, so a Class 4 roof has a real margin over the storms we actually get.

How the shingle does it

Two ways. Some Class 4 shingles use a rubberized, polymer-modified asphalt (SBS) that flexes on impact instead of fracturing. Others add a reinforcing layer under the granules. Owens Corning's Duration FLEX uses the SBS approach and keeps the SureNail reinforced nail strip, so it also carries the same wind performance as standard Duration. On the roof it looks identical to a standard Duration shingle.

Who should have it

• Lake homes and open lots around Lake Chemung, Thompson Lake, the Chain of Lakes and the farm country west and north of Howell, where there is no tree cover to break up hail
• Homeowners who have already had one hail claim and do not want a second
• Anyone re-roofing a home they intend to keep for 20 years or more
• Homes where a cosmetic-damage exclusion has been added to the insurance policy, because a roof that does not mark is the best protection against that exclusion

What to ask your insurance agent

Many Michigan carriers treat a UL 2218 Class 4 roof differently from a standard one. Ask your agent whether your policy recognizes Class 4 before you choose a shingle, and ask what documentation they need — we provide the manufacturer certification and the installation record for every Class 4 roof we install.

The honest downside

Class 4 is not a hail-proof roof. Very large hail can still damage it, and it does nothing for wind if the crew nails it wrong. It is a stronger version of the same shingle, installed the same way. If your home is in a wooded subdivision with mature trees on every side, standard Duration installed as a full system is still an excellent roof and we will tell you so.

See both on a real roof

We install Duration and Duration FLEX side by side across the county and can show you homes with each. Call (810) 588-3933 for a free inspection and a written recommendation for your specific lot.