Commercial skylight leak repair, resealing, and flashing replacement for Louisville buildings — curb-mounted and deck-mounted skylights on flat roofs across Jefferson County.
A leaking skylight in a Louisville commercial building fails at one of three points: the glazing seal, the curb-to-membrane flashing, or the skylight frame itself. Each failure mode has a different repair. We find which one it is and fix it with documented methodology — not sealant over the exterior frame and a hope.
Commercial skylights in Louisville's climate are under sustained thermal stress. The Ohio Valley sees temperature swings of 100 degrees or more between winter lows and summer highs — skylights on a Louisville building go from near-zero to 90-plus within the same annual cycle. That movement stresses every seal in the skylight assembly: the glazing seal between the glass or polycarbonate panel and the frame, the frame-to-curb seal, and the curb-to-roof membrane flashing. Louisville's ice storms add intermittent structural loading that can crack aging polycarbonate panels and compress curb seals beyond their recovery point.
Skylight leak investigations on Louisville commercial buildings require distinguishing between three failure modes that present similarly inside the building — water on the interior surface below the skylight — but have very different repair scopes. A glazing seal failure means water is entering between the panel and the frame; sealant replacement or panel re-bedding is the repair. A curb flashing failure means water is entering at the membrane-to-curb interface; re-flashing the curb is the repair. A frame or panel crack means water is entering through a structural failure in the skylight unit itself; unit replacement may be the only permanent repair. We do not skip the diagnostic step.
We repair commercial skylights on all commercial flat-roof system types — TPO, EPDM, PVC, modified bitumen, and BUR. The curb flashing repair is system-specific: re-flashing a curb on a TPO field requires TPO-compatible flashing material and heat-weld termination; re-flashing on a modified bitumen field requires compatible hot- or cold-process termination. Mixing incompatible materials at the curb flashing creates a new failure point within seasons.
Glazing seal deterioration: The most common skylight failure on Louisville commercial buildings older than fifteen years. Silicone or butyl glazing sealants at the panel-to-frame interface age under UV exposure and thermal cycling, losing elasticity and adhesion. Failed glazing seals allow water to enter the frame channel and migrate to the interior. In winter, ice formation in the frame channel accelerates seal failure — ice expanding inside the channel pushes the glazing sealant out of the joint. We re-seal or re-bed the panel depending on the extent of seal failure.
Curb flashing failure: The curb — the raised frame that elevates the skylight above the roof field — must be flashed at its base to the roof membrane. Curb flashing fails through differential movement (the skylight curb and the roof deck move differently under thermal load), adhesive bond failure at the curb base, and at counter-flashing terminations at the top of the curb. Louisville's freeze-thaw cycling is particularly damaging to curb flashings because it creates repeated small movements that accumulate into open gaps. Re-flashing the curb is a permanent repair when done with compatible materials and proper lap dimensions.
Polycarbonate panel cracking: Louisville's ice load events can crack aged polycarbonate dome skylights — the dome geometry concentrates ice load at the base ring, and panels that have been UV-degraded for more than twenty years become brittle under that load. Cracked polycarbonate cannot be permanently sealed; the panel must be replaced. We supply and install replacement polycarbonate dome and flat panels in standard commercial skylight sizes and can source custom sizes for non-standard configurations.
Frame corrosion and joint separation: Aluminum skylight frames on older Louisville commercial buildings — common on buildings constructed in the 1970s and 1980s in the J-Town industrial corridor and the Downtown office stock — develop frame joint separation as the original butyl tape or compression gaskets age. Separated frame joints allow water to enter the frame channel from above. Frame joint repair involves recompressing the joints and resealing with compatible sealant, or, where the frame is structurally compromised, replacement of the skylight unit.
Diagnosis first: We do not start with sealant. Every skylight leak investigation begins with a roof-side inspection of the glazing seal, the curb flashing, the frame joint condition, and the panel condition — and an interior inspection to map where water is appearing and its relationship to the skylight geometry. Where the failure point is not immediately obvious, we use controlled water testing at the skylight to isolate the entry point.
Scope documentation: Before any repair, we produce a written scope identifying the failure mode, the repair method, the materials to be used, and the expected service life of the repair. Glazing re-seal on a sound panel — eight to fifteen years. Curb re-flashing with compatible materials — fifteen to twenty years in Louisville's climate. Panel replacement — twenty-plus years on new polycarbonate under current UV stabilizer standards.
Repair closeout: Every skylight repair includes a post-repair water test and a written closeout document with before-and-after photos. For repairs where the interior damage required ceiling or insulation replacement below the skylight, we note the interior scope separately as a general-contractor item, since that work is outside our roofing scope.
Skylight repair is the right scope when the failure is in the flashing system or the glazing seal and the skylight unit itself is structurally sound. Skylight replacement is the right scope when the panel is cracked or beyond repair, when the frame has structural failures that compromise the unit's waterproofing integrity, or when the unit is old enough that repair costs approach replacement costs over the capital horizon. We give you that comparison directly — repair cost versus replacement cost at the current failure and projected failure frequency — so the capital decision has a factual basis.
For Louisville buildings undergoing broader roof replacement projects, existing skylights are an integration point. We coordinate skylight curb flashing with the new membrane installation so the skylight is properly integrated into the new system from day one, rather than re-flashed as an afterthought after the field membrane is installed.
Yes. Downtown Louisville and the Whiskey Row conversion district have a significant inventory of older commercial buildings with skylights that predate modern glazing standards — some are original wire glass or early polycarbonate in frames that have seen multiple roofing cycles. We assess each unit individually for repair versus replacement potential and work with the building's overall roof system, which in the Downtown historic district often involves modified bitumen or BUR systems rather than single-ply.
It is common but it is not normal in the sense of being acceptable. Leaking only during ice or snow events on a Louisville commercial building points to either a curb flashing failure that allows water to enter when ice-melt volume exceeds the drainage capacity of the lap, or to a glazing seal failure that is only overcome when ice load compresses the frame joint and forces water through. Either failure mode is repairable. It will not get better on its own — ice events will widen both failure modes over successive winters.
A curb re-flash with compatible materials — matching the field membrane system — and proper lap dimensions and termination should last fifteen to twenty years in Louisville's climate. The failure point is typically the top-of-curb termination, which takes the most thermal movement. We design the top termination with a cap flashing that allows movement rather than a rigid seal, which extends the service life significantly compared to a surface-sealed termination.
We serve commercial buildings across Jefferson County — Downtown, NuLu, Jeffersontown, the Shelbyville Road corridor, and the full Louisville metro. Written scope, material specification, and closeout documentation on every repair.
Tell us about the building and the roof problem. We'll document it and put a plan in writing — no pressure, no boilerplate.
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