What Is the Difference Between Owens Corning Duration FLEX and Duration STORM?

Owens Corning Duration FLEX and Duration STORM are both UL 2218 Class 4 impact-rated architectural shingles, and the main difference is how each one earns that rating. Duration FLEX is made with a proprietary blend of SBS polymer-modified asphalt that Owens Corning says gives the shingle a rubberizing effect and greater flexibility, while Duration STORM uses WeatherGuard Technology, an integrated polymeric backing on the shingle. Beyond that, the two share a lot: the same nominal size, SureNail Technology, a limited lifetime warranty, wind coverage up to 160 mph when component requirements are met, and 25 years of algae resistance coverage with an approved Owens Corning hip and ridge product.

What a Class 4 rating does not change is the warranty on hail. In its guide to Class 4 shingles, Owens Corning notes that Duration STORM and Duration FLEX are tested in a laboratory and classified as UL 2218 and FM 4473 Class 4 impact resistant, but that the results "do not guarantee that the shingle will resist all weather conditions" and that hail damage is specifically excluded from warranty coverage. The value of a Class 4 roof lies in better resistance to impact and possible insurance savings, not in a manufacturer promise to replace hail-damaged shingles. This guide compares the two shingles, their colors, the insurance and warranty details, and how to decide whether either one makes sense for your home.

How Do Duration FLEX and Duration STORM Earn a Class 4 Rating?

UL 2218 is one of the most common tests used to rate the impact resistance of asphalt shingles, and Owens Corning says it is nicknamed "the steel ball test." A steel ball is dropped onto an installed shingle several times, and the shingle is then turned over and inspected for cracks or breaks that could let water through. Owens Corning lists the four classes this way:

• Class 4: 2 inch steel ball dropped from 20 feet

• Class 3: 1 3/4 inch ball from 17 feet

• Class 2: 1 1/2 inch ball from 15 feet

• Class 1: 1 1/4 inch ball from 12 feet

Owens Corning says impact resistant shingles are commonly engineered in one of two ways, and its two Class 4 Duration shingles use one each:

1. Duration FLEX (SBS modified asphalt): Rubber-like SBS (styrene-butadiene-styrene) polymers are blended into the asphalt, making the shingle more pliable and better able to recover from an impact.

2. Duration STORM (reinforced backing): A reinforcing, polymer-based mesh is added to the back of the shingle to strengthen it and help reduce cracking on impact.

For comparison, Owens Corning rates its standard TruDefinition Duration shingle Class 3. If you want to see what impact damage looks like on an ordinary roof, our article on what roof hail damage looks like on shingles walks through the signs.

What Are the Main Differences Between FLEX and STORM?

Here is how the two compare based on Owens Corning's product pages and announcements:

• Technology: FLEX uses SBS polymer modified asphalt throughout the shingle. STORM uses WeatherGuard Technology, an integrated polymeric backing material.

• Launch claims: When Owens Corning introduced Duration FLEX on February 12, 2019, it said the shingle offered 42 percent better nail pull resistance against wind than standard shingles, more than 10 percent greater tear strength, and that it lays flat more quickly during installation.

• Hip and ridge requirement: Owens Corning's STORM page says corresponding hip and ridge shingles are required to complete a UL 2218 Class 4 roof system for warranty coverage. Owens Corning's ImpactRidge hip and ridge shingles are SBS modified, rated Class 4, and pair with both FLEX and STORM.

• Colors: The two lines share five colors, and each has colors the other does not (see the next section).

Both shingles use Owens Corning's SureNail Technology, a fabric strip in the nailing area that Owens Corning credits with helping to prevent nail blow-through and pull-through. Our article on how SureNail Technology sets Owens Corning apart explains the design.

Which Colors Come in Duration FLEX and Duration STORM?

Color can decide the choice, because the two color lineups overlap only partly. Here is what Owens Corning's product pages show:

• In both FLEX and STORM: Brownwood, Driftwood, Estate Gray, Onyx Black and Teak

• FLEX only: Black Sable, Sand Dune, Storm Cloud and Summer Harvest

• STORM only: Antique Silver and Desert Tan

Owens Corning describes Storm Cloud as a medium warm gray with an overall green undertone, and Antique Silver as a neutral light gray made with white and gray granules. Several Duration colors, including Williamsburg Gray and Slatestone Gray, do not appear in either Class 4 lineup, so if your heart is set on one of those colors, the standard Class 3 Duration is the Owens Corning option.

Owens Corning also notes that product availability varies by location, so confirm with your contractor which Class 4 shingles and colors are available for your address.

Can a Class 4 Roof Lower Your Insurance Premium?

It can, but only your insurer can say for sure. Owens Corning's FLEX page says the shingle may qualify for a homeowner insurance discount, and its STORM page says that in some areas homeowners may qualify for premium discounts. Both tell you to check with your insurance company.

Owens Corning's Class 4 guide adds two details worth asking about before you sign a contract:

• Some insurers require both the shingles and the hip and ridge shingles to be rated Class 4.

• Some also require off-ridge vents.

Ask your agent what documentation they need, such as the product name and proof of installation, and whether the discount applies to your policy. Our post on how your roof can affect home insurance premiums covers the broader picture.

What Does the Warranty Cover on a FLEX or STORM Roof?

Both shingles carry Owens Corning's limited lifetime warranty. Their product pages list:

1. Wind: up to 160 mph when Owens Corning component requirements are met and starter shingles are installed on both the eaves and rakes.

2. Algae: 25 years of algae resistance coverage when the roof includes an approved Owens Corning hip and ridge product.

3. Hail: not covered. Owens Corning states that hail damage is specifically excluded from warranty coverage, even on its Class 4 shingles.

Hail damage is a homeowners insurance matter, not a warranty matter, so keep your policy details with your roofing paperwork. Owens Corning also notes that a Class 4 rating does not necessarily mean higher wind resistance, since wind ratings are a separate classification. For a general overview of what shingle warranties include, read what shingle warranties usually cover.

Is a Class 4 Shingle Worth It for a Pittsburgh-Area Home?

It depends on your insurance, your color choice and your budget. Owens Corning's Class 4 guide cites Insurance Information Institute figures showing the five states with the most major hail events in 2022 were Texas, Nebraska, Minnesota, Kansas and South Dakota. Pennsylvania was not on that list, so for most local homeowners the decision rests less on regional averages than on their own policy and priorities.

A Class 4 shingle is worth a closer look if:

• Your insurer offers a meaningful discount for a Class 4 roof

• The color you want is available in FLEX or STORM

• You plan to stay in the home long enough to benefit from any premium savings

The standard Duration shingle may be the better fit if your preferred color is only offered in Duration, or if your insurer offers no discount. Our article on whether impact-resistant shingles are worth the cost goes deeper on the tradeoffs.

FAQ

Are Duration FLEX and Duration STORM both Class 4 shingles?

Yes. Owens Corning classifies both as UL 2218 and FM 4473 Class 4 impact resistant shingles.

Which is better, Duration FLEX or Duration STORM?

Neither is better across the board. FLEX uses SBS modified asphalt and offers colors such as Black Sable, Sand Dune and Summer Harvest, while STORM uses a polymeric backing and offers Antique Silver and Desert Tan. Color availability and your insurer's requirements usually decide it.

Does the Owens Corning warranty cover hail damage on Class 4 shingles?

No. Owens Corning states that hail damage is specifically excluded from coverage under the warranty, even for Duration FLEX and Duration STORM.

Do I need special hip and ridge shingles for a Class 4 roof?

Owens Corning's STORM page says corresponding hip and ridge shingles are required to complete a Class 4 roof system for warranty coverage, and some insurers require Class 4 hip and ridge for a discount. Owens Corning's ImpactRidge hip and ridge shingles are rated Class 4 and pair with both lines.

Are Class 4 shingles more wind resistant?

Not necessarily. Owens Corning notes that wind ratings are a separate classification from impact ratings.

Can I get a Class 4 roof in Williamsburg Gray?

Not from Owens Corning's current Class 4 lineups. Williamsburg Gray appears in the standard TruDefinition Duration line, which is rated Class 3.

Why Pittsburgh Homeowners Trust Craig Gouker Roofing With Their Roof

Craig Gouker Roofing has replaced roofs across the Pittsburgh area since 1991 and works exclusively with Owens Corning Duration and Designer Duration shingles as an Owens Corning Platinum Preferred Contractor. If impact resistance is a priority, ask your estimator which Owens Corning options are available for your project and which components your insurer requires. Every installation is backed by a 5-year workmanship guarantee, and you can learn more on our residential roof replacement page.

Visit Craig Gouker Roofing or call (412) 664-7679 today. Contact us for more information.