Sika Sarnafil Hail Performance

Extreme weather such as hail has been increasing all over the world, and the roofing industry has been working hard to develop systems that can withstand it. After seeing years of damage from large size hail in certain regions of the United States, international insurer FM Global, along with the aid of FM Approvals, created hail test methods and ratings, including their latest for “Very Severe Hail.” When it comes to extreme weather, including hail, Sika Sarnafil has always had you covered, so it should come as no surprise that we have done it again! As the first PVC manufacturer with Very Severe Hail (VSH) approvals over gypsum cover board, you can rest assured your Sarnafil roof system can withstand these extreme elements or any other need your building might have.

Heads Up! Watch Out for Hail

Hail damage is no laughing matter. The impact energy that a single hailstone can have is enough to possibly puncture and severely damage roof coverings if not built with resistance in mind, even in moderate rated hail zones. You might be asking yourself, how can something so small cause so much damage to your roof?

Although many of us know hail as small ice balls that may seem similar to snow or sleet, they can vary in size and shape, as well as the amount of damage they can do. These balls of ice can form during storms year-round and have been known to cause some serious damage. Since hail is a solid ball of ice, the effects are quite different than other forms of precipitation like rain or snow. 

Sika Sarnafil Very Severe Hail Rated

If you’ve ever been hit by a falling acorn before, you know that small things falling from the sky can still hurt if given enough speed. Since hail is falling from a higher distance, it’s able to build up a lot of force. In fact, a falling piece of hail can reach incredibly high speeds – medium-sized balls are expected to fall between 25 and 40 mph, while larger balls can fall as fast as 72 mph according to the NOAA.

Extreme weather such as hailstorms can lead to serious damage if your roof system is not designed for that level of hail impact. Dents and cracks in your roof system or possible larger damage could lead to costly repairs or possible disruptions in operations inside your building. Damaged roofs can allow water to penetrate through to the interior of the building. Sometimes the damage is apparent immediately, whereas in other instances the damage may not become apparent for quite some time after the storm.

If your building is located within the severe to moderate hail zone, being prepared for hail is the only way to save you from spending money on costly repairs and/or roof replacement after something happens. By installing a roof system that is rated for your area's level of extreme weather needs or higher from the start, you can help mitigate potential losses down the line.

Heeding Hail Warnings

To ensure that the roof systems you are considering protecting your assets are truly Very Severe Hail ready, FM Global and FM Approvals designed rigorous hail tests to assess roof assemblies. To achieve a very severe hail rating (VSH), two-inch diameter ice balls are fired from air cannons at speeds of up to 160 feet per second. A ball of ice of that size, traveling at that high of a velocity could pose a serious problem, especially if those roof assemblies have been in place for several years and weathered. This test is done on three separate roof assembly samples: a brand-new system, a UV weathered system, and a UV weathered system that is also heat aged for prior to testing. A resilient roof designed for such events is able to resist the simulated hail impact even after these harsh conditioning procedures.

Hail Ball Measurements

FM Global has divided the country based on the areas’ historical hail exposure. These regions are now broken down into Moderate Hail, Severe Hail, and Very Severe Hail.

  • Moderate Hail (Grey): Hail size does not exceed 1.75" (44mm) diameter
  • Severe Hail (Light Blue): Hail size exceeds 1.75" (44mm) but remains under 2" (51 mm) in diameter
  • Very Severe Hail (Teal): Hail size exceeds 2" (51mm) in diameter


According to FM Global's new hail zone map, 'hot zones' in the United States include Texas, Oklahoma, Colorado, Wyoming, North Dakota, South Dakota, Kansas, Missouri, Iowa, Minnesota, Montana, New Mexico and some parts of Arkansas. Surrounding the 'hot zone' area is the Severe Hail zone and then the Moderate Hail zone. Depending on your location, it might be time to consider a more resilient roofing system designed specifically for your location. Even outside of the red zone, installing a VSH-rated system ensures your building is ready no matter what is thrown at it.

Sika Sarnafil wants to help protect your building from the elements and the possibility of damage, which is why we’ve developed many system options that can meet your building’s hail needs.

FM Global's Hail Zone Map:

hail size of a quarter

Moderate Hail (Grey):
Hail size < 1.75 in. (44 mm)

hail size of a golf ball

Severe Hail (Light Blue):
Hail size ≥ 1.75 in. (44 mm) and
< 2 in. (51 mm)

hail size of a billiard ball

Very Severe Hail (Teal):
Hail Size ≥ 2 in. (51 mm)

Very Severe Hail FM Rated Map
Sika Sarnafil Can Help

As the first PVC manufacturer to achieve FM’s VSH rating over gypsum-based cover board, Sika Sarnafil can offer you a resilient roof system to help you weather the storm. Not only are we the first PVC membrane to accomplish this rating, but we also have many systems that meet any hail rating for your project's specific needs. With over 55 years of roofing and waterproofing experience, Sika Sarnafil is the worldwide market leader in PVC membrane technology.

VSH rated roof systems are resilient, meaning they can withstand impact and continue to perform from what would otherwise damage roofing products. This helps to ensure that your roof will not only survive the first hailstorm but keep you covered afterward and when the next hailstorm arrives as well.

Industry best practice for developing a resilient roof, is that thicker membranes are better. When it comes to Very Severe Hail protection this is also true. Sika provides a thickness guarantee on our Sarnafil membranes. When you purchase any Sarnafil branded membrane we guarantee that it is produced at or above the labeled thickness for no extra cost or lead time. With a thicker membrane, your roof has more material to protect what is underneath.

Very Severe Hail Test

Weather can be destructive, but we’re here to protect your building from the elements. Sika Sarnafil is leading the way in hail protection as the first PVC roofing membrane to achieve Very Severe Hail Ratings from FM Global! Now you can rest assured knowing the Sarnafil systems you know and love, can be built to withstand your extreme weather needs. Check out this cool R&D test video to see how we reached those goals to offer you an amazing product.