Hail Dents on a Metal Roof: Which Ones Matter After the Storm

A hailstorm on a metal roof leaves different evidence than one on asphalt shingles. There are no granules to find in the gutters and no mat to test with a thumbnail. What is left is a field of dents, and the question for a St. Louis homeowner is which of them still matter for how the roof sheds water and holds its fasteners. Most dents in the flat of a panel are cosmetic. A handful are not, and the difference shows up only when someone looks at the coating, the seams and the fasteners rather than counting marks from the driveway.

Start with the metal you have

Metal roofs in the St. Louis area are mostly steel or aluminum panels with a painted or coated finish. The gauge and the alloy set how easily a panel dents. Thinner aluminum dents at a smaller stone size than heavier steel, so two roofs in the same storm can show very different counts even when the hail was the same. A standing seam panel with raised ribs resists dents differently than a corrugated or ribbed panel, and a lighter gauge shows a dent more clearly across a large flat. Write the metal, the gauge and the profile on your first photo sheet, along with the slope and the date of the storm. A dent count means little without the panel it sits on.

Dents that are only dents

A dent in the flat of a panel is often cosmetic. If the paint or coating is unbroken, the metal underneath is still protected, and the panel still sheds water along its full length. Dents that sit away from seams, laps and fasteners usually do not change how the roof performs. They do change how it looks. Whether to leave a cosmetic dent alone is a decision you make with your own budget and your own eye, and a good roofer will say so plainly instead of pushing a replacement you do not need.

Dents that change how the roof works

Four places deserve a closer look on every slope that took hail.

• Dents that crack the coating. A dent can craze or split the finish at its crown, leaving bare metal in a spot the coating was meant to guard. In a St. Louis winter, with road salt splashing up from the drive and ice melt pooling at the eave, that bare spot is where corrosion tends to begin.
• Dents at a seam or lap. Where two panels overlap, or where a standing seam closes, a dent can keep the seam from sitting flat. A seam that does not close is a path for wind-driven rain, and the leak may show up on a ceiling a long way from the dent.
• Dents at a fastener or clip. A dent around a screw or a clip can stress the washer or pull the fastener out of true. Check each fastener line on the hit slopes, and look for a washer that is cracked, flattened or lifted.
• Dents in the trim. Eave, rake and ridge trim move water off the roof. A dent in trim can bend the edge that is meant to drip, and it can open a gap at the joint behind it.

Tell a dent from waviness

Metal can look hit when it is not. Large flat panels expand and contract through St. Louis summers and winters, and thin metal can show a wavy appearance called oil canning. Oil canning is a normal result of thin metal under temperature swings, and it is not hail. A true hail dent has a defined edge, and the finish inside it often looks different in raking light. Lay a straightedge across the suspect area. If the wave moves with the sun or the heat, it is oil canning. If the dent stays put when the panel cools, it belongs in the count.

What to photograph

Photograph each dent in two views. First straight on, with a ruler laid beside it so the size is in the frame. Then at a low angle with the sun raking across the panel, which brings out the edge and any coating crack. Shoot a third frame that shows the dent next to a seam or fastener so its location is clear. Note the slope, the panel and the count for each area. Keep the original files from your phone rather than screenshots, because the originals carry the capture details that matter if anyone reviews the file later.

What it costs

On metal, repair often means replacing a damaged panel instead of hammering out a dent. The price is usually counted by the panel, with trim, sealant and any cut-and-fit work listed on separate lines. Ask whether the damaged panel can come out without disturbing the seams around it, and whether the profile and finish are still made. If they are not, the scope needs a named fallback so you are not left with a panel that does not match the rest of the run.

Missouri has no matching statute for roofs. Whether a replacement panel has to match the existing one turns on the wording of your policy, so read that wording with your insurer rather than assuming the answer from the roof itself.

Missouri law (RSMo 407.725) forbids a roofing contractor from representing or negotiating a homeowner's insurance claim. What Keys does is document the damage, put a written scope with photos and measurements in your hands, and attend as the contractor while you deal with your own insurer.

What to ask

• Which metal, gauge and profile is on each slope, and which slopes took hail?
• Which dents did you count as functional, and what did you find under the ones that cracked the coating?
• How did you count the dents, per panel or per area, and how large was the area?
• Can a damaged panel be replaced without disturbing the seams around it, and is the profile still made?
• What is the price per panel and per trim piece, written out line by line?
• Will you hand me the written scope with photos and measurements so I can take it to my insurer myself?