Hail Proof Roofing
A roof that can stand up against any hail storm event depends on your view of what should be considered a roof. If you are considering living in a bunker underground, with at least 6" of soil and a solid concrete slab as a "roof", then good news, there are options for you out there. Unfortunately for those of us that own a home or building above ground, there isn’t a single solution that truly provides a "hail-proof" option for your roof.
Protection against Hail Storms
In order to understand how well a roofing material will hold up against hail, it is first important to understand how these materials are judged. A common test for measuring the effectiveness of a roofing material against hail damage would be the UL 2218: Standard for Impact Resistance of Prepared Roof Covering Materials. This test uses a steel ball to impact various locations on a particular assembly including edges, seams or unsupported joints or sections. While this test provides one of the best gauges of how a roof will hold up against a hail storm, a steel ball is not a hail stone, and even this extensive test does not guarantee a material or product will hold up against a severe hail storm.
Impact Testing: UL 2218
While UL 2218 testing is one the best ways to gauge a material or product’s ability to hold up against a severe hail storm, hail can still ultimately damage or penetrate many of the toughest roof systems. The reason behind this is simple. A 1 ½ lb. hail stone (3.25 inches) will travel at speeds up to 105mph. The power behind these hail stones is incredible. While a material may resist a single impact, multiple impacts in the same location will eventually cause damage or penetration of the roofing materials.
Fortunately, baseball sized hail stones don’t happen every day. For the majority of homes, a Class 4 UL 2218 rating will be sufficient in protecting your home from roof penetration due to a hail storm. A Class 4 test involves a steel ball weighing 1-2lbs being dropped from a height of 12 to 20 feet on the same location of the assembly. This is considered by most professionals (and insurance companies) as the highest level of protection a roof covering material can provide.
Metal Roofing for Hail Protection
At this point I think it is my responsibility to state that I do work for a metal manufacturer. My knowledge of shingle, shake or tile roofing is not sufficient to speak of the benefits versus risks with hail damage. I would recommend that each person look into all of their options before making a smart decision on their next roof.
Metal roofing has always been known as one of the toughest materials available to use for a roof, and most roofing panels carry Class 3 or 4 ratings. Just choosing any metal roof will leave many owners with regrets after the next big hail storm. This has to do with the testing itself. While UL 2218 (and other testing standards) measure the ability of a material to stand up to rips, tears, holes and penetrating issues, it does not consider the visual appearance of the material once the testing is complete. In other words, your roof may still be 100% structurally sound after a severe hail storm, but will also look like someone took a baseball bat to every inch of your roof. Beyond a visual nuisance, some insurance companies who provide a discount for metal roofing will not cover cosmetic damage caused by hail as your roof is still intact and structurally sound.
Cosmetic Hail Dents & Dimples
To minimize cosmetic damage, you need to take into account the design of the panel itself. Many standing seam roofs have large, flat surfaces that show smaller imperfections due to their smooth uniform appearance. Breaking up a standing seam panel with striations or ribs will help minimize the visual impact of dents, as well as help with expansion and contraction in areas prone to temperature swings.
One of the best panel styles at minimizing the visual impact of dents from hail is the corrugated roofing panel. The design of a corrugated panel makes it extremely durable as the corrugations greatly increase steel’s already impressive tensile strength. This improved strength makes corrugated panels harder to have damage inflicted upon their surface. If imperfections are created, the corrugated panels have the added benefit of breaking up the sight lines and hiding these small visual imperfections better than other panels styles. For these reasons, corrugated roofing panels are among the most durable and best options for roofs in areas subject to hail storms.
Thicker is Better?
A common misconception when it comes to protecting a structure against hail damage is the thickness (gauge in the case of steel) of the material. Metal panels are made of a series of layers, some using galvanized coatings, others using galvalume coatings to create a combination of metals, primers and paint coatings. These materials are created in steel mills who use various techniques to create the best possible product for the widest potential series of use cases.
While thicker steel is often better at prevent dents and surface damage, it is also often less flexible than a thinner material that may dent easier, but is less likely to tear. While most panels ranging from 22 to 29 gauge steel offer a relatively similar level of protection, there is a difference in how each thickness will perform against different aspects of a hail impact.
Selecting Quality Metal Coils
Because of the incredibly sensitive process of milling steel for roofing uses, Bridger Steel has chosen to only use domestic steel mills using the highest level of technology to mill our base steel. We also use a minimum measurement to measure our coil, something uncommon in the industry. This means that we require a minimum thickness in each coil we purchase, ensuring that every panel we run adheres to our requirements. As steel coils are sold by total weight (after paint and primer has been applied), many manufacturers choose a maximum thickness for cost purposes, but also preventing them from ensuring a consistent product.
Choosing the Right Underlayment
An important factor in choosing a roofing envelope that holds up to most hail storms includes selecting the right underlayment material. Whether you are choosing a metal, shingle, shake or tile roof, choosing the right underlayment should be considered a critical portion of your decision-making process. Like visible roof coverings, underlayment materials are also tested for impacts. Often people spend a significant amount of time carefully choosing the surface of their roof system, without ever considering this second layer of defense. Underlayments can not only help protect your home from impact, but are also tested for water, air and fire ratings.
Get Advice from Experts
Ultimately there are a number of factors to consider when choosing a roof to help hold up against severe hail storms. Choosing the right materials, selecting the right installers, and speaking to your insurance company about the actual coverage of your plan are among the most important choices to make.
Other quick tips to designing a hail-resistant roof include:
- Maintaining a minimum roof slope of 6:12 has been known to help minimize hail damage
- Use roof decking or well supported plywood sheathing materials under a tested underlayment
While there are no true hail-proof solutions, choosing the right roof covering, along with a quality underlayment will help your roof hold up against most of the strongest storms. Doing the research, speaking to professionals about your options, and making decisions on which factors mean the most to you and your home will help you choose the right solution for your region.
If you need assistance, Bridger Steel has a team of roofing specialists that can help you select the right option for your roof (even if it’s not metal), and find a local contractor to help you with installation.
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