Skylight Leaks and Seal Failure
in Charlotte, NC

Skylights require a multi-component flashing system — a sill flashing at the downslope edge, step flashings along the sides, and a saddle or cricket at the upslope edge — and any weakness in this system allows Charlotte's frequent heavy downpours to force water under the shingle line and into the curb assembly. Many older Charlotte skylights were installed with simple surface-applied lead or aluminum flashing without a step system, which performs adequately in light rain but fails under the intense rainfall rates that Piedmont thunderstorms routinely produce.

The neoprene or EPDM gaskets that seal the glazing panel to the skylight frame degrade progressively under Charlotte's high UV index and thermal stress, becoming hard, brittle, and shrunken — eventually pulling away from the frame contact surface and allowing windblown rain to enter between the glass and the frame directly. This failure mode is distinct from a flashing problem because water enters the skylight unit itself rather than around its perimeter, often appearing as a slow drip from the center of the glazing rather than the edge.

In Charlotte winters — particularly during the cold snaps between December and February when interior humidity is elevated from heating systems and occupant activity — single-pane or older double-pane skylights act as thermal bridges where warm interior air contacts the cold glazing surface and deposits moisture as condensation, which then runs down the frame and drips onto interior finishes in a pattern identical to an active roof leak. This problem is often mistaken for a flashing failure and leads homeowners to pursue unnecessary exterior repairs when the actual issue is the thermal performance of the skylight unit itself.