Commercial Skylight Repair in Cleveland, OH

Commercial skylight leaks are among the most misdiagnosed repair calls in the Cleveland market. The water appears on the interior at the skylight frame — dripping from the edge of the glazing, running down the interior curb face, or pooling on the ceiling tile directly below the skylight — and the building owner or facility manager concludes that the glazing is cracked or the glazing seal has failed. In most cases, the glazing is intact and the leak source is the curb-to-field membrane flashing that surrounds the skylight at the roof level.

The mechanism is the same freeze-thaw pattern that drives parapet flashing failure in Cleveland: the skylight curb is a raised wooden or metal frame that sits on the roof deck, with the flat roof membrane terminated and flashed against the curb face. Every winter, the curb thermally expands and contracts at a different rate than the surrounding roof membrane. Over 10 to 20 Cleveland winters, this differential movement works the flashing termination away from the curb face, creating a gap that admits water on every rain event and ice on every freeze. The water runs down the interior of the curb and appears at the glazing — where the building owner interprets it as a glazing failure.

Our approach starts with the diagnostic. We inspect the curb flashing from the roof surface before we assess the glazing. On most Cleveland commercial skylight leak calls, the repair scope is curb flashing re-termination — not glazing replacement. Glazing that is genuinely cracked or delaminated gets addressed separately, but we do not replace functioning glazing to solve a flashing problem.

Skylight Curb Flashing Failure in the Cleveland Freeze-Thaw Climate

Curb-to-field membrane flashing on commercial skylights is installed at original construction as an upturned base flashing that terminates against the curb face at the standard 8-inch minimum height. On TPO systems, the base flashing is a TPO-bonded flashing that is heat-welded to the field membrane and adhered to the curb face. On modified bitumen systems, the base flashing is a granule-surface stripping built up against the curb. Both configurations are subject to the same Cleveland failure mode: differential thermal movement between the rigid curb and the flexible membrane pulls the flashing termination away from the curb face.

Wood curbs are particularly vulnerable in the Cleveland climate. Wood absorbs moisture, swells in summer, contracts in winter, and over 15 to 20 years develops surface deterioration and dimensional instability that makes re-termination of the flashing against the original curb impractical. When the curb substrate is deteriorated, the full scope is curb replacement — new pressure-treated wood or metal curb, new base flashing, and a new field membrane termination. We assess curb substrate condition before specifying the flashing repair scope.

Metal curbs — factory-fabricated curbs that come with commercial skylight units — are more dimensionally stable than wood but present a different challenge: thermal bridges. A metal curb in direct contact with a Cleveland winter ambient of -10°F creates a thermal bridge that generates condensation on the interior curb face. On occupied commercial buildings, this condensation can be misidentified as a leak. We assess thermal bridge conditions on metal-curb skylights and recommend interior condensation countermeasures where the building's interior humidity creates condensation conditions.

Glazing Assessment and Replacement

Polycarbonate and acrylic glazing panels on commercial skylights have a service life of 15 to 25 years in the Cleveland climate. UV exposure yellows the panels progressively, reducing light transmission. Hailstone impact leaves surface pitting that scatters light and can penetrate the panel at large stone diameters. Cleveland's spring hail season — April through June — is the primary source of glazing impact damage on commercial skylights.

Glass-glazed commercial skylights — more common in Class A office and institutional buildings — are not subject to UV yellowing but are vulnerable to seal failure at the insulating glass unit perimeter. Failed IG unit seals produce interior fogging between the glass lites. The repair is IG unit replacement, not full skylight replacement. We assess IG unit seal condition as part of the skylight inspection.

Skylight glazing that is structurally intact but showing hail impact pitting, UV yellowing beyond 40% light-transmission reduction, or cracked glazing from thermal stress — common on large polycarbonate units over 10 years old in the Cleveland climate — is a glazing replacement scope. We coordinate glazing replacement with the curb flashing scope when both are needed, avoiding the cost of separate mobilizations.

Snow Load and Structural Considerations on Cleveland Commercial Skylights

Commercial skylights in the Cleveland snow belt — particularly on buildings east of I-271 in Lake County and the eastern suburbs — carry snow load conditions that glazing manufacturers specify against ground snow load data for the building's location. Polycarbonate panels rated for 20 psf ground snow load may be undersized for the 40-to-50-inch lake-effect events that affect the Willoughby-to-Painesville corridor. We note skylight snow load ratings on inspection reports for buildings in the heavy snow belt and flag undersized glazing for review.

Drifting snow against skylight curbs creates asymmetric loading conditions that are distinct from uniform snow loading. A large HVAC unit or parapet that deflects prevailing wind into a drift adjacent to a skylight curb can create snow accumulation 3 to 4 times deeper than the surrounding roof surface. Curbs in drift accumulation zones need clear drainage paths for melt to prevent ice dam formation at the curb base — a detail we address in the repair scope when the curb is in a documented drift location.

Commercial skylight leaking in your Cleveland building?

We will assess the curb flashing and the glazing separately, identify the actual source, and produce a repair scope that addresses the entry point — not the interior symptom.

Frequently Asked Questions