Skylight Leaking? It Is Usually the Skylight, Not the Roof

A leaking skylight is usually the skylight itself, not the surrounding roof. Fog or standing water between the glass panes means a failed factory seal in the glass unit. A stain along the inside of the frame after wind-driven rain usually means the perimeter sealant or flashing has failed. Skylights are the second most reported leak source on our calls, right behind chimneys, and most of them get fixed by replacing or reflashing the unit, not by touching the shingles around it.

I am Aaron Scott, licensed Michigan residential builder and owner of Roofing Army. On the roofs we tear off across Southeast Michigan, skylights come up constantly: 61 homeowners have reported a skylight as their leak source on our calls this year, trailing only chimneys. Most callers assume the roof failed around the skylight. In our experience, the skylight unit itself, its glass seal, its frame sealant, or its factory flashing kit, is the more common culprit, and telling the two apart before anyone gets on a ladder saves a wasted service call.

Why Is My Skylight Leaking If the Rest of the Roof Is Fine?

A skylight is a manufactured unit dropped into a hole cut in your roof deck, sealed to the surrounding shingles with its own flashing kit, and sealed to itself with a factory glass seal and a bead of perimeter sealant. Any one of those three seals can fail on its own schedule, completely independent of how healthy the shingles around it are. That is why a five-year-old roof can have a leaking skylight, and a twenty-year-old roof can have a skylight that has never leaked a drop: the roof's age tells you almost nothing about the skylight's condition.

There are three separate places water gets in, and each one points to a different fix.

• The glass seal, between the panes. Modern skylights use insulated glass, two panes with a sealed air gap between them. That seal fails with age and sun exposure. Once it does, moisture gets between the panes and you see fog, haze, or actual water sitting inside the glass itself. This is not a leak into your house yet, but it is a sign the unit's weather barrier is compromised and full water intrusion often follows.
• The frame sealant, around the inside edge. The rubber gasket and sealant that seal the sash to the frame dry out and crack after years of UV exposure and temperature swings. Once that seal opens, wind-driven rain works its way in along the inside edge of the frame, especially during a sideways rain rather than a straight-down one.
• The flashing kit, where the unit meets the roof. Skylights are sealed to the roof deck with a manufacturer-specific flashing kit: a sill piece at the bottom, step pieces woven up each side, and a head piece across the top, the same layered logic as step flashing on a chimney or wall. When that kit was installed wrong, reused from an old skylight, or shingled around instead of properly stepped, water gets behind it and shows up as a stain along the top or sides of the skylight shaft.

Skylight Leaking From Inside the Frame? That Points to the Seal, Not the Roof

If the leak shows up as moisture along the inside perimeter of the glass, or fog trapped between two panes that will not wipe away because it is on the inside surface, that is a seal failure inside the unit itself. No amount of reflashing or recaulking the roof around it fixes that, because the water is not coming from outside the frame. The only real fix is a new sash or a full skylight replacement, since the glass unit is sealed at the factory and is not something a crew reseals on a roof.

This is also the case a homeowner most often mistakes for "the roof is leaking," because the stain appears right where the skylight meets the ceiling, and it is easy to assume the nearest shingles are the source.

Skylight Leaking in Heavy Rain? Check the Flashing First

A leak that only shows up during a hard, wind-driven rain, and stays dry through a light steady rain, almost always points to the flashing kit rather than the glass seal. Wind pushes water sideways and up under a flashing lap that would otherwise shed water downhill just fine. This is the same pattern we look for on chimney counter flashing: a seal that only fails under wind pressure is a flashing problem, not a material failure.

On a tear-off, we always pull old skylight flashing rather than shingle around it, because reused flashing on a new roof carries the same risk it does on a chimney: flashing that already leaked once rarely seals correctly a second time around new shingles.

Is It a Leak or Just Condensation?

Not every wet skylight is a leak. Warm, humid house air rising into a cold skylight shaft can condense on the glass or metal frame in winter and drip back down, looking exactly like a leak from the outside. This is the same mechanism behind attic condensation on a roof deck, just happening at the skylight shaft instead of the rafters. A few tells separate the two: condensation shows up on cold mornings regardless of whether it rained, tends to appear on the glass itself rather than the frame edge, and often clears up once the sun warms the room. A true leak tracks with rain or snowmelt and shows up at the frame edge or the drywall around the shaft, not on the glass surface.

Who Fixes a Leaking Skylight, a Roofer or the Skylight Company?

A roofer handles all of the actual repair work: reflashing, resealing the frame, or ordering and installing a replacement unit. A skylight manufacturer generally only gets involved for a warranty claim on a defective seal, and even then, a roofer typically does the physical swap. There is rarely a reason to call the manufacturer directly before calling the contractor who will do the work.

How Much Does It Cost to Fix or Replace a Leaking Skylight?

Across the repair quotes we wrote this year, the median price was $1,109, with the middle half falling between $600 and $2,658, and most jobs are one technician for about half a day. A skylight specifically, priced as its own line item, runs a median of $580, with the middle half between $260 and $978, depending on whether the job is a simple reseal, a full flashing kit replacement, or a new glass unit. On a full roof replacement, we replace the skylight outright on about 5% of the roofs we tear off. When a skylight is already showing wear and the roof is being torn off anyway, replacing it at the same time is almost always the better call than paying to reflash an aging unit and risk doing the labor twice.

Most of the skylights we encounter and replace are Velux units. Velux backs its own glass seal against fogging for 20 years and backs a correctly installed skylight and its factory flashing kit against leaks for 10 years, according to Velux's own warranty terms. That 10-year installation warranty is void the moment a flashing kit is improvised instead of installed per the manufacturer's instructions, which is exactly why we never shingle around an old skylight or reuse someone else's flashing kit on a new one.

Is a Leaking Skylight Covered by Homeowners Insurance?

It depends entirely on the cause, and this is a question for your policy and your insurer, not a blanket yes or no. A skylight cracked by a falling branch or hail during a documented storm is a sudden, covered event on most policies. A skylight leaking because a decade-old glass seal or frame sealant wore out is gradual deterioration, which nearly every homeowners policy excludes as a maintenance issue rather than a covered loss. If you are unsure which side of that line your situation falls on, our guides to what roof damage insurance actually covers and why roof claims get denied walk through how insurers draw that line in more detail.

Get the Right Fix the First Time

A leaking skylight wastes time and money when it gets treated as a roofing problem when it is really a failed glass seal, or vice versa. Every inspection we do checks the glass seal, the frame sealant, and the flashing kit separately, and we will tell you plainly which one is actually failing before quoting anything. For the roof-side version of this same diagnosis, see our guide to chimney leaks and who fixes what, and for how a skylight replacement fits into a larger project, see what is included in a roof replacement quote.

We serve Southeast Michigan from offices in Oxford, Ferndale, and Rochester Hills. See real project pricing in our job gallery, or schedule a free inspection to find out which of the three skylight problems you actually have.