Home › Common Problems › Skylight Leaks and Seal Failure
Skylight Leaks and Seal Failure
in Raleigh, NC
Skylights are a popular feature in Raleigh's newer neighborhoods and in renovated mid-century homes throughout areas like Five Points and Boylan Heights, but they represent one of the more complex waterproofing details on any roof. The extreme UV exposure of a Raleigh summer degrades the EPDM gaskets and silicone seals around skylight frames far faster than the surrounding shingles, and the thermal expansion cycling between our hot summers and winter cold snaps works metal curb flashings loose over time. Because skylight leaks often travel along the ceiling drywall before appearing as a stain, homeowners frequently discover the problem well after significant hidden damage has accumulated.
Telltale Signs
Warning Signs to Watch For
- Water staining or drips appearing on the ceiling or wall near a skylight after rain
- Visible fogging, condensation, or moisture between double-pane skylight glazing panels
- Cracked, shrunken, or absent sealant visible around the skylight curb or frame
- Bubbling or peeling paint on the interior ceiling surrounding the skylight
- Daylight or drafts detectable around the interior skylight trim or frame
- Rust streaking visible on the exterior skylight frame or surrounding flashing
Root Causes
What Causes Skylight Leaks and Seal Failure?
Curb Flashing Deterioration
Raleigh's summer UV index is among the highest in the Southeast Atlantic states, and the metal curb flashing and adhesive sealant at the base of a skylight curb are directly exposed to that radiation for hours each day. After 10–15 years, the sealant cures to a brittle state and cracks, and the step flashing around the curb separates from thermal expansion, opening gaps that direct rainfall from the field of the roof straight down into the ceiling assembly.
The Fix
Skylight Curb Flashing Replacement
The existing flashing kit is completely removed, the curb is inspected for rot or damage, and a new manufacturer-matched or universal flashing kit is installed with proper step-and-counter-flashing integration into the shingle field and sealed with high-temp flexible sealant appropriate for Raleigh's temperature range.
Failed Glazing Seal or Cracked Dome
Polycarbonate skylight domes and dual-pane glazing units are subjected to significant thermal stress in Raleigh's climate, cycling between winter lows near 20°F and summer highs where the glazing surface itself can exceed 130°F. This cycling eventually causes the edge seals of IGU glazing units to fail, allowing moisture infiltration between the panes, or causes polycarbonate domes to develop microcracks that admit water directly into the well.
The Fix
Skylight Glazing Unit Replacement or Full Skylight Replacement
Failed IGU units are replaced with new argon-filled dual-pane glazing matched to the existing frame, or for domes with structural cracking the entire skylight unit is replaced with a current-model unit that meets NC Energy Code requirements for solar heat gain coefficient, improving both leak resistance and energy performance.
Condensation from Interior Humidity
Raleigh's muggy summers push indoor relative humidity high in homes without properly sized dehumidification, and bathroom skylights in particular accumulate condensation on the interior glazing and frame during the shoulder seasons when cold nights follow warm humid days. This condensation runs down the interior frame, saturates the drywall at the curb perimeter, and is frequently misidentified as an exterior leak when the moisture source is entirely from inside the home.
The Fix
Interior Skylight Insulation and Humidity Control
The skylight well is inspected and air-sealed at the ceiling perimeter, insulation is added around the curb in the attic space to raise the interior surface temperature above the dew point, and a whole-home or room humidity management assessment is performed to address the source of excess interior moisture.
Self-Diagnosis
Which Cause Applies to You?
Check the signs you're observing to narrow down the likely root cause before your inspection.
| What You're Seeing | Curb Flashing Deterioration | Failed Glazing Seal or Cracked Dome | Condensation from Interior Humidity |
|---|---|---|---|
| Water dripping at the curb base during or immediately after rain events | |||
| Fogging or cloudiness visible between the two panes of a fixed skylight | |||
| Ceiling staining appears only in cold mornings after warm humid nights | |||
| Exterior flashing lifted or separated visible from a ladder inspection | |||
| Cracked or yellowed polycarbonate dome surface visible from the roof | |||
| Dripping at skylight frame only in winter, not during summer storms |
Free Inspection
Get a Diagnosis in Raleigh
An on-site inspection is the only way to confirm which cause applies to your property. Free, no obligation.
(984) 500-1173Free on-site inspection
Written estimate before work starts
Serving Raleigh & surrounding areas
Other Problems
Also Helpful