Metal Roofs in Hail, Wind and Hurricanes: What Upstate Storms Do to a Roof

You are standing in the yard after a storm, looking up. Maybe there are shingles on the lawn, a limb across the ridge, or just a bad feeling about the noise last night. The first useful question is what kind of storm it was, because wind, hail and falling trees damage a roof in different ways.

The National Weather Service office in Greenville-Spartanburg covers Anderson County. Its severe weather climatology for the area says damaging thunderstorm wind is the most common form of severe weather here, that large hail peaks in late spring and early summer, and that tornadoes are most frequent in spring. The NWS also notes that damaging wind from thunderstorms is much more common than tornado damage, and that debris laid out in straight lines usually points to straight-line wind rather than a tornado.

Hurricanes reach the Upstate too, as remnants rather than as coastal landfalls. The South Carolina Emergency Management Division's hurricane guide says hurricanes and tropical storms can impact every part of the state, even areas far inland, and credits Hurricane Helene (2024) with 21 tornadoes in South Carolina. The NWS Greenville-Spartanburg report on Helene lists a 63 knot gust (roughly 72 mph) at Anderson Regional Airport and describes widespread wind damage, with trees and power lines down across the area. Our post Can Hurricanes Affect a Metal Roof? covers the question in general terms; this guide gets into the mechanics.

Wind does not push straight down on a roof. It speeds up over the ridge and around the corners, which lowers the pressure above the surface and creates uplift. The strongest suction sits at the eaves, rakes, ridges and corners. If the covering, the trim or the deck lets go there, wind gets under the rest and peels it back.

That is why the Insurance Institute for Business and Home Safety (IBHS) builds its FORTIFIED Roof standard around attachment and edges rather than around the covering alone. FORTIFIED calls for ring-shank nails in a tighter pattern to hold the roof deck, a sealed roof deck so water stays out if the covering blows off, a wider drip edge with a fully adhered starter strip for what IBHS calls a stronger edge system, and attic vents rated to resist wind and rain. IBHS describes edges as a common starting point for wind damage. FEMA's 2023 Wind Retrofit Guide (P-804) lists the same basic package: inspect and improve deck attachment, seal the deck, improve underlayment details at the eaves, and install a wind-resistant covering.

For metal, the same logic applies to clips, fasteners and edge metal. IBHS requires metal roof systems in FORTIFIED homes to be tested for site-specific design pressures, which is a reminder that the panel profile, the fastening pattern and the trim details are what get tested, not the word metal.

UL 2218 is the Standard for Impact Resistance of Prepared Roof Covering Materials. UL Solutions says it was developed in the 1990s with industry and insurance companies, and that it works by dropping steel balls from set heights to replicate the impact energy of hailstones. The results are four classes, Class 1 through Class 4, with Class 4 the highest.

UL states that its requirements are based on physical breach damage viewed from the back side of the sample, and that they do not account for denting or granule loss. In plain words, a Class 4 panel passed a test for cracking and tearing through. The test says nothing about whether the panel will show dents afterward.

IBHS's 2013 hail demonstration showed the difference. Both metal roof sections took visible dents but no punctures, which IBHS classed as cosmetic damage. Metal installed directly over the roof deck took smaller, shallower dents than metal installed over a layer of old shingles. IBHS's own FORTIFIED hail supplement asks for UL 2218 Class 4 on metal panels. The NWS considers hail of 1 inch (about a quarter) or larger to be severe. If appearance after hail matters to you, ask the manufacturer in writing what its finish warranty says about dents and cosmetic damage, and read your insurance policy for any cosmetic damage wording. The sibling guide on insurance claims vs paying out of pocket explains why that matters.

Do not get on the roof, and do not lean a ladder against wet gutters. Walk the yard, look from upstairs windows, and use binoculars or your phone's zoom. IBHS's hail damage guide points out that collateral damage on softer items around the house is a good sign hail actually hit, and that some marks are look-alikes rather than hail.

• Dents in gutters, downspouts, metal flashing, window screens, the mailbox and the air conditioner's fins. IBHS lists these as indicators that hail occurred.
• Spatter marks, which IBHS describes as clean spots where hail knocked dirt or oxidation off metal. Spatter itself is not damage, but it tells you hail fell.
• Look-alikes to rule out: manufacturing defects, blisters, mechanical marks from installation, and general granule loss along shingle edges. IBHS says real hail damage falls in a random pattern.
• Lifted or missing panels, trim, ridge cap or shingles, and anything flapping. IBHS notes ridge caps are one of the most hail-vulnerable parts of a shingle roof.
• Debris on the roof, limbs resting on panels, and shingle pieces or screws in the yard and gutters.
• Inside: new stains on ceilings, damp insulation at the attic hatch, or daylight where there was none. Our post 7 Easy Steps to Recover from Roof Hail Damage adds the claim side of this.

When a tropical system comes through the Upstate, the roof problems are usually trees, wind-driven rain and lost power rather than coastal surge. In Helene, the NWS described widespread wind damage with trees and power lines down. A limb that punctures a panel or a shingle roof lets water in fast, and the sealed roof deck that IBHS and FEMA recommend is the backup layer that keeps a punctured covering from turning into a soaked ceiling.

Tornadoes travel with tropical systems as well as with spring storms. If a tornado or straight-line wind hits a roof directly, the covering type matters less than the attachment of the deck to the framing and the framing to the walls. Our post Tornado Damage in the Greenville Area? covers that side of it.

Safety comes before any inspection. The NWS says to go inside a sturdy building during a high wind warning and to treat power lines lying on the ground as live. FEMA's recovery guidance says to treat all loose or downed lines as energized and to report them to the power company. If a tree is on the house, leave and call 911 before you think about the roof.

A metal roof does not make a house storm-proof. If your current roof came through the storm with a few lifted shingles and sound decking, a repair may be all you need, and we offer repairs and preventative maintenance on shingle, metal and flat roofs through our roof repair and maintenance service. Impact-rated shingles exist too; IBHS publishes its own hail impact ratings for shingles.

If you are weighing a new roof after a storm, read the residential metal roofing page for the building types we cover, then ask for the panel gauge, coating, UL 2218 class, fastening pattern and edge details in writing. Compare them against the manufacturer's installation guide rather than against a brochure.

If the storm has already done damage, the next step is to record it before anything is moved. The guide on how to document roof storm damage walks through photos, weather records and the adjuster visit. If water is coming in right now, go to what to do about a roof leak right now first.