How We Assess Hail Damage on Commercial Flat Roofs
Visual survey: We walk the full membrane field and photograph every impact mark we identify, keyed to a zone diagram. Impact marks on TPO and EPDM show as circular depressions or punctures in the membrane surface. On ballasted systems, hail displaces ballast and can expose unprotected membrane sections in low-ballast areas.
Bruising assessment: Impact bruising that does not create visible punctures is assessed by feeling the membrane surface for soft spots, locations where the insulation board beneath has been compressed. Compressed insulation under the membrane creates a thermal bridge and reduces the membrane's ability to resist further stress. We document every bruise location on the zone diagram and GPS-coordinate larger roofs where manual mapping is not sufficient.
Metal components: Hail damage to soft metal on commercial roofs, aluminum coping caps, lead flashings, HVAC cabinet covers, and sheet-metal curb flashings, is highly diagnostic. Consistent circular dents on soft metal at a specific density per square foot is the standard for establishing a significant hail event at that location. We photograph and measure metal impact density as part of every hail inspection.
Repair Scope for Hail-Damaged Commercial Roofs
Localized punctures, holes large enough to allow immediate water entry, are addressed in the emergency response phase. We carry TPO and EPDM patching materials for immediate temporary seal on actively leaking punctures while the full inspection scope is completed.
Membrane replacement in heavily impacted zones is the appropriate scope when bruising density or puncture frequency exceeds a threshold where patching becomes a patchwork exercise. For TPO and EPDM systems, we replace impacted membrane sections with new full-width sheets fully welded at the seams to the existing system. This maintains manufacturer warranty coverage on the repaired sections.
On modified bitumen systems, which are common on older commercial buildings along the Downtown St Louis and South City corridors, hail impacts can delaminate the cap sheet from the base sheet at impact locations. We assess delamination with a probe and replace cap sheet sections where delamination extends beyond individual impact points. A delaminated cap sheet zone does not protect the base sheet beneath it and needs to be replaced rather than patched.
Insurance Documentation for Hail Damage Claims
Missouri insurance adjusters handling commercial hail claims expect calibrated documentation: impact counts per 100-square-foot test square, soft-metal dent measurements, membrane damage photographs with GPS coordinates on large roofs. We produce that format as standard output from our hail inspections. The documentation is not produced for a specific adjuster's preference but to the objective standard that holds up under independent review.
We distinguish between hail damage and pre-existing deterioration. A roof with aging sealant around penetrations and weathered membrane edges has pre-existing condition that does not become a hail claim just because a storm passed over the building. Our reports are accurate on that distinction, which means the damage we document is defensible when the adjuster or a second inspector reviews the claim.
For hail events that produce large-area damage across the metro, the supercell events that affect entire commercial districts simultaneously, we prioritize inspection scheduling to get clients documented within the 30-day window that is most defensible for claims purposes. Do not wait to see if leaks develop. By the time leaks appear, the membrane has often been further stressed by subsequent weather that complicates the damage attribution.
Hail-Impact-Rated Assemblies and Future Risk Reduction
After a hail damage repair, the replacement scope is an opportunity to upgrade the membrane and cover board assembly to a hail-impact-rated specification. A high-density cover board, HD polyiso or a gypsum-based board such as DensDeck, installed under the new membrane distributes hail impact energy and achieves FM 4473 or UL 2218 Class 4 impact ratings on the appropriate membrane and cover board combination.
We document the impact-rated assembly in the repair closeout package so that if a subsequent hail event affects the building, the scope and impact rating are already on paper for the insurance conversation rather than reconstructed after the fact. That documentation is a material asset when the building's property insurer reviews the claim, because a building with a documented Class 4 impact-rated assembly is in a materially stronger position than one without the assembly documentation.
Modified Bitumen Hail Assessment in the South City Corridor
The South City industrial and commercial corridors, Soulard, Cherokee Street, Carondelet, and the warehouse districts extending south toward I-255, carry a significant population of modified bitumen and built-up roofing systems on older masonry commercial buildings. Hail damage assessment on these surfaces requires specific technique: granule loss mapping on modified bitumen cap sheets, aggregate displacement assessment on BUR systems, and delamination probing where the cap sheet surface shows concentrated impact patterns.
Granule loss from hail events on modified bitumen is the functional impairment indicator that insurance claims should document even before active leaks appear. The granules protect the asphalt matrix from UV degradation. When hail removes granules from a significant area of the cap sheet, the underlying asphalt is exposed to Missouri's UV load and surface temperatures, which accelerates brittleness and cracking. The damage is real and measurable even when the roof is not actively leaking on the date of inspection.
The 30-Day Inspection Window and Claim Position
The Missouri insurance claim window for hail damage is typically one year from the event date, but the most defensible documentation is produced within 30 days of the event. Weather, maintenance traffic, and any emergency dry-in or temporary repairs can alter the visible damage pattern between the event date and a delayed inspection. A date-of-loss report produced within 30 days captures the damage in its closest-to-event state and is the most credible evidence in a contested claim.
For commercial buildings on our annual maintenance program, we track significant hail events in the metro and proactively schedule post-event inspections before the 30-day window passes. Building owners do not have to monitor weather data or decide whether an event was significant enough to justify an inspection. We make that judgment call for the buildings on our maintenance roster and notify the building owner when a proactive inspection is warranted.
