Commercial Roofs After Hail or High Wind: Inspection, Records and Rating-Safe Repairs

Pin down what hit the building

Start with the weather record, because hail size drives damage. The Storm Prediction Center posts storm reports by day; its August 10, 2020 page, for example, lists measured gusts and damage reports by location and time. The permanent record is NOAA's Storm Events Database, where each event carries a magnitude, time and narrative; its search page notes that events take three months to appear.

Neither source tells you what fell on your roof. RICOWI's Texas A&M report found a mix of hail sizes and impact frequency not only between buildings but on the same roof, and its North Texas report points out that official and third-party sources give maximum hail size but say nothing about quantity. Measure on site.

Walk the roof: where damage hides

SPRI's guidance is to inspect every low-slope roof at least twice a year and after any major storm, checking the perimeter for loose metal or fasteners, the flashings around penetrations, and the drains. Note what has changed since the last inspection, and bring in the installing contractor or a Registered Roof Consultant if questions come up.

After hail, look past the obvious. RICOWI's 2025 campus report separates spatter marks and dented metal, sometimes treated as cosmetic, from functional damage, and flags three hidden forms:

• Crushed insulation under TPO. A sheet showing only divots can sit over partly crushed insulation, leaving voids that weaken support and reduce thermal value.
• Fractured metal coatings. On standing seam panels, a cracked factory coating may be invisible to the eye and detectable only in a lab, yet it can speed corrosion.
• Granule loss on modified bitumen. Impact damage showed as circular bare spots about 2 inches across, unlike the even, gradual look of age-related loss.

After wind, go to the corners and edges first. RICOWI's Hurricane Ian report recorded copings torn loose because of too few fasteners, and membranes peeled back at the corners and perimeters where uplift is highest; the details are in our wind uplift guide.

Test before you trust the surface

The Texas A&M investigators did no destructive testing and did not examine membrane undersides, where fractures sometimes show, so their visual survey could not rule hidden damage out. SPRI's advice for any re-cover decision points the same way: make core cuts to learn how the system is built, including whether a vapor barrier would stop wet insulation from drying, and run a moisture survey to find where wet insulation is.

Document it for the owner and the insurer

• Photograph hail on the ground and on the roof beside a scale, and record impact counts per 100 square feet, the measure RICOWI uses.
• Map damage by location, separating the field, perimeter, corners, seams and fastener rows.
• Pull the roof file: the tested assembly and its FM listing, warranty terms, and past inspection reports for comparison.
• Save the event records from NCEI and SPC with the date of loss.

The National Roofing Directory's guides to documenting roof damage for a claim and why roof claims get denied cover the insurance side.

Repairs that keep the rating

Two lines in FM 4470 matter most after a storm. First, maintenance coatings, applied over a functioning roof system, do not increase its fire, wind or hail resistance, so a coating is not a hail upgrade. Second, a certified assembly's components may not be substituted without the certification agency's prior authorization, and that rule reaches the cover board, insulation and fasteners, not just the membrane.

Replacement edge metal should be an ES-1 tested product from a fabricator that tested it or is licensed and audited to make it, per SPRI's position. And check state licensing before the crew arrives: Illinois, for one, requires an unlimited roofing license for commercial and industrial roofs (225 ILCS 335).

When RICOWI deploys

RICOWI's Hail Investigation Program mobilizes for storms with hail larger than 1.5 inches that causes significant damage over 5 square miles or more in a target area, and it also studies areas of 0.5- to 1.5-inch hail to find damage thresholds. Investigators serve in three-person teams, commit five days and cover their own expenses; the program is seeking volunteers for 2026. RICOWI's fall 2026 seminar and meetings are set for November 3-4 at Oak Ridge National Laboratory, according to its website. Its NRD page is in the directory.

Contractors who handle post-storm commercial work can claim a National Roofing Directory listing, see the membership levels, and get Storm Watch alerts for chosen states through The Roofing Wire.

Frequently asked questions

How soon should a commercial roof be inspected after a storm?

SPRI advises inspecting low-slope roofs after any major storm, in addition to at least two routine inspections a year. Confirm the date and hail size from the weather record, then check perimeters, flashings and drains.

Can a roof coating repair hail damage?

Not in rating terms. FM 4470 defines maintenance coatings as products applied over a functioning roof system and states they do not increase fire, wind or hail resistance, so damaged components still need proper repair.

Why take core samples after hail if the membrane looks intact?

Because the damage may be underneath. RICOWI notes that crushed insulation and underside fractures can hide below a TPO sheet that shows only divots, and SPRI recommends core cuts and moisture surveys before deciding whether to re-cover.