Skylight leaks are among the most persistent and difficult-to-resolve roof repair issues in Palm Beach County — because skylight installations involve the intersection of multiple building systems and failure modes that require targeted diagnosis to distinguish. Florida Building Code Section 2405 governs skylight installation requirements, and most skylight leaks on PBC homes result from flashing failures, condensation misidentification, or installation errors rather than glazing failures. Understanding which failure mode you are dealing with determines whether the repair is a $300 flashing fix or a $3,000 unit replacement.

The Four Skylight Failure Modes in South Florida

Skylight leaks in Palm Beach County fall into four distinct categories, each requiring a different diagnostic approach and repair strategy.

Failure Mode 1 — Step flashing and counter-flashing failure. The most common skylight leak source on tile and shingle roofs in PBC. The skylight curb is flashed to the roof deck with step flashing (individual metal pieces interwoven with the tile or shingle courses) and counter-flashing (a cap flashing attached to the curb that overlaps the step flashing). When either element fails — through corrosion, improper installation, or thermal movement — water enters the gap between the curb and the roof surface. This type of failure produces water at the skylight during or immediately after rainfall, typically at one corner or along one side of the unit.

Failure Mode 2 — Condensation misidentified as a leak. In South Florida's high-humidity climate, condensation on the interior glazing surface of a skylight can produce dripping that appears identical to an active leak. Single-pane skylights in particular — and even some older double-pane units with compromised seals — collect condensation during the temperature differential between the cool interior air conditioning environment and the hot exterior. Condensation drips are most common in the morning after a night of air conditioning and are not correlated with rainfall. Misidentifying condensation as a leak leads to unnecessary flashing repairs that do not resolve the actual issue.

Failure Mode 3 — Glazing seal failure. Double-pane skylights have an insulating gas seal between the two glazing layers. When this seal fails — a common occurrence on skylight units over 15-20 years old — the insulating property is lost and the risk of interior condensation increases significantly. Seal failure is visible as fogging or moisture between the glazing layers that cannot be cleaned from either interior or exterior surface. A skylight with seal failure requires unit replacement — the seal cannot be repaired in the field.

Failure Mode 4 — Curb flashing failure at the roof deck interface. On flat and low-slope roof sections, skylight curbs are embedded in the membrane system. When the membrane at the curb base fails — through membrane shrinkage, thermal cycling, or inadequate overlap — water enters at the base of the curb directly. This failure mode is more common on older TPO and modified bitumen systems where the curb flashing has separated from the field membrane.

FBC Section 2405 — Skylight Requirements for PBC

Florida Building Code Section 2405 establishes the requirements for skylights in Florida, including glazing material specifications, frame construction requirements, and installation requirements for hurricane-prone regions. In Palm Beach County's wind speed zone, skylights must meet impact resistance requirements — either through impact-rated glazing or through a tested, listed impact-protective cover system. Skylights installed before the current FBC edition may not meet current impact resistance requirements, which creates a code upgrade obligation when a skylight requiring replacement is in a home that does not currently have compliant glazing.

The practical implication for PBC homeowners: a skylight that was installed in 1995 and is now leaking may need to be replaced with a unit that meets current FBC Section 2405 impact requirements, not just like-for-like replacement of the same unit. Confirm with your contractor whether the proposed replacement unit is FBC Section 2405 compliant for your specific location's design wind speed before the purchase is made.

The Repair vs Replacement Decision for Skylights

Skylight repair is appropriate for: isolated flashing failures on units with intact glazing and functional seals, condensation issues addressed by adding ventilation rather than unit replacement, and minor curb flashing repairs on flat roof systems. Skylight replacement is required when: the glazing seal has failed (fogging between panes), the unit is over 20 years old and the glazing or frame has deteriorated beyond repair, the unit does not meet current FBC impact requirements and replacement is triggered by a repair permit, or the curb itself has failed structurally and cannot be reused. A skylight unit replacement in Palm Beach County costs $800-$3,500 for the unit plus installation — labor and flashing are additional. This cost range makes the repair vs replace decision economically meaningful when a flashing repair at $300-$600 is genuinely addressing an isolated failure on an otherwise functional unit.

  • Diagnose the specific failure mode before any repair: flashing, condensation, seal failure, or curb base failure
  • Test for condensation: does dripping occur in mornings after AC use without recent rainfall? If yes, condensation not a leak
  • Check for fogging between glazing layers — indicates seal failure requiring unit replacement, not flashing repair
  • For tile and shingle roofs, inspect step flashing and counter-flashing on all four sides of the curb
  • For flat roof sections, inspect curb base membrane overlap — shrinkage creates gaps at this location
  • Confirm replacement units meet FBC Section 2405 impact resistance requirements for PBC wind zone
  • Confirm repair or replacement requires a permit — skylight work in PBC typically requires permitting
  • Verify CCC license at myfloridalicense.com for any contractor performing skylight repair or replacement