Metal roofs are highly resistant to hail damage. However, you may sometimes notice small dimples or chips on your roof after a major hailstorm comes through your area. Is this type of damage something that requires you to replace your roof?
Whether or not your roof will require replacement depends on if the hail damage is cosmetic or functional. Functional damage is damage to your roof that could potentially result in a water leak, whereas cosmetic damage doesn't affect the integrity of your roof. In most cases, hail damage to a metal roof only results in minor cosmetic damage. You only need to replace your metal roof after a hailstorm if it has suffered functional damage and its structure has been compromised. To help you tell the difference between cosmetic and functional damage, here are some types of hail damage that can qualify as functional.
Damage to Panels That Exposes the Steel Core
Hailstones that are large and dense can cause the coating on metal roof panels to chip. While this creates a visibly damaged area on your roof, it doesn't always mean that your roof has suffered functional damage. Most metal roofs have a zinc or galvanized layer underneath the coating that serves as a method to protect the inner steel core from rust. If this layer was not damaged by hail, then the hail damage is only cosmetic. Your roof is still protected from rust and leaks.
However, if the hail damage went all the way to the inner steel core and exposed it to the elements, then it qualifies as functional damage. Your damaged roof panel will eventually rust since corrosive rainwater will collect in the dimpled area and slowly rust the steel core. This only applies to metal roofs that are susceptible to rust in the first place. If your metal roof is made out of aluminum, for example, then even the inner core is immune to rust damage. In this case, the hailstone would need to break through the inner core and damage the underlayment underneath the metal roof panel in order to qualify as functional damage; this is an extremely rare event.
Warped Panels That Prevent Water Shedding
Repeated hail damage over a long period of time can eventually cause the metal panels on your roof to begin to slightly warp. In most cases, this is only a cosmetic issue — you may notice your roofing panels beginning to slightly curl up at the eaves. It only counts as functional damage if the deformed roof panels prevent your roof from shedding water, which can happen if the warped roof panels create a valley in your roof that collects water.
Damaged Seams That Allow Water to Travel Underneath a Metal Panel
Sometimes severe weather has particularly great aim and hailstones will repeatedly strike the seam between two metal panels on your roof. This can cause a tiny crack to form beneath the seam, allowing water to flow underneath one of the metal panels and onto your roof's underlayment, where it can become trapped and cause a roof leak. Severe damage to your metal roofing seams, therefore, can qualify as functional damage.
Damaged Vents or Flashings
While your metal roof is very hail-resistant, your other roofing features are not. Vents and roof flashings are more vulnerable to hail damage and may break or become deformed when hailstones strike them. In this case, no functional damage has been done to your roof itself. However, you'll need to replace the damaged vents or flashing in order to prevent a potential leak.
How can you tell if your roof suffered functional damage? Call a roof replacement service to examine your roof and determine whether the damage is cosmetic or functional. A residential roofing professional will be able to tell you if hailstones have managed to open up a potential leak in your roof or if the damage is limited to the surface of your metal panels. If your roof has suffered functional damage, then it is important that you have the roof replacement service replace the damaged panels in order to prevent potential water damage from a leak.