Pittsburgh experiences an average of 40 freeze-thaw cycles per winter. Water penetrates small gaps in skylight flashing during rain or snowmelt. When temperatures drop below freezing overnight, that trapped water expands with significant force, widening cracks in sealant and pushing flashing away from the curb. By March, a skylight that showed no leaks in October can have compromised flashing on all four sides. Heavy spring rains then expose these failures, creating sudden roof window leaking during storm events that seem to appear out of nowhere.
Local roofers who understand Pittsburgh's climate design flashing systems that accommodate expansion and contraction. We use flexible sealants rated for temperature swings from negative 20 to 180 degrees. We mechanically fasten all flashing components rather than relying solely on adhesive bonds. We also account for Pittsburgh's average annual rainfall of 38 inches when we size and position flashing to handle high-volume water flow. Choosing a contractor with regional experience means your skylight repair addresses the specific conditions that caused the original failure.