Skylight Repair vs. Replacement: A Comparison

A leaking or fogged skylight is one of the more anxious roofing problems for an island homeowner, because it sits at the intersection of two systems: the glass unit itself and the roof it penetrates. On the San Juan Islands, with roughly 40 inches of annual rain, wind-driven storms, and salt air working on every metal component, a skylight problem rarely stays small if it is ignored. The core question is always the same. Do you repair the skylight you have, or replace it entirely? This comparison lays out how to decide.

What Actually Fails on a Skylight

Understanding the failure points makes the repair-versus-replace call much clearer.

• Flashing and seal. The most common leak source is not the glass but the flashing and sealant where the skylight meets the roof. Wind-driven island rain finds any gap.
• Seal failure (fogging). When the seal between insulated glass panes fails, moisture gets trapped and the unit fogs permanently. That is a unit problem, not a flashing problem.
• Cracked glass or dome. Impact, hail, or a fallen branch can crack the pane.
• Aged framing and gaskets. Older units develop brittle gaskets and corroded frames, especially near saltwater.
• Condensation confusion. Sometimes what looks like a leak is interior condensation from poor ventilation, not a roof failure at all.

The Head-to-Head Comparison

The table below frames the decision across the factors that matter most on an island roof.

Factor Repair Replacement Best when Flashing/seal leak, minor gasket issue, unit under ~10 years Fogged seal, cracked glass, unit 15+ years, repeated leaks Typical cost range $450–$1,500 $1,200–$3,500+ Disruption Low; often a half-day Higher; roof opening reworked Longevity gained A few years if unit is aging 20+ years with a modern unit Energy performance Unchanged Improved (modern glazing) Risk of recurrence Higher on old units Low Roof integration Reuses existing curb/opening Fresh flashing and membrane

Costs shown are an estimate, not a quote. On the islands, expect roughly 10 to 25 percent above comparable mainland pricing because crews and materials cross by ferry and old units leave the same way.

When Repair Is the Right Call

Repair makes sense when the skylight unit itself is sound and the failure is at the connection to the roof.

Good Repair Scenarios

• The leak traces to failed flashing or dried sealant, and the glass is intact and clear.
• The unit is relatively young, generally under about ten years.
• A single gasket or a cracked exterior dome can be replaced without disturbing the whole assembly.

The key to a lasting island repair is doing the flashing right. That means corrosion-resistant metal, fresh sealant rated for the exposure, and ice-and-water membrane integrated at the skylight where wind-driven rain concentrates. A sealant-only smear over old flashing is a stopgap that will fail again by the next November.

When Replacement Wins

Replacement is the honest answer more often than homeowners expect, because patching an aging unit often just delays a second bill.

Clear Replacement Signals

• Persistent fogging between panes. A failed insulated seal cannot be repaired; the unit must be replaced.
• Cracked glass. Structural glass damage means a new unit.
• Repeated leaks. If a skylight has leaked, been patched, and leaked again, the assembly is telling you something.
• Age. Units past 15 to 20 years are near end of life; reworking the flashing on an old, inefficient unit rarely pays off.
• Roof replacement timing. If you are re-roofing anyway, replace skylights at the same time. Opening the roof twice on an island, with ferry-driven labor costs, is money wasted.

A modern replacement also upgrades energy performance. Older single- or early double-pane units bleed heat; today's low-emissivity glazing cuts that loss and reduces the condensation that gets mistaken for leaks.

The Island-Specific Factors

Several local realities should weigh on the decision.

Salt air. Near saltwater, corroded frames and fasteners argue for replacement with corrosion-resistant components rather than nursing old hardware along.

Access and staging. Ferry logistics make every visit more expensive, so consolidating work, replacing rather than making a second repair trip, often costs less over time.

Moss and shade. Skylights on north slopes under Douglas fir collect debris and moss around the curb, which traps water. Whatever you choose, keep the surrounding roof clear.

Wind. West-side exposures drive rain uphill and sideways, stressing flashing hard. That environment rewards a properly integrated new curb and flashing over an old, marginal seal.

How to Decide, Step by Step

Homeowners weighing options for https://andersonsbra343.evergrovio.com/posts/understanding-roof-underlayment-and-ice-and-water-shield can work through a simple sequence:

1. Confirm the source. Is it flashing, a fogged seal, cracked glass, or interior condensation? The fix depends entirely on this.
2. Check the age. Under ten years and structurally sound leans repair. Fifteen-plus leans replace.
3. Count the leaks. First leak on a young unit: repair. Repeat offender: replace.
4. Consider timing. Re-roofing soon? Replace the skylight in the same project.
5. Account for salt and access. Corrosion and ferry costs both tilt the math toward doing it once, correctly.

The Bottom Line

Repair a young, sound skylight with a flashing or seal problem, and insist on corrosion-resistant flashing done to island standards. Replace a fogged, cracked, or aging unit, and always replace skylights during a re-roof rather than reopening the roof later. On the islands, where weather is relentless and every trip across the water carries a premium, the durable choice usually beats the cheap one within a few seasons.

About the Author

Nora Whitfield is a home-improvement writer and former glazing technician who has worked on daylighting and roof penetrations throughout the maritime Pacific Northwest. She focuses on helping homeowners make weather-smart repair-or-replace decisions.