A drip or a spreading stain under a skylight sets off understandable alarm — there is a hole in your roof with glass in it. But effective skylight leak repair starts with an accurate diagnosis, because a large share of the "leaks" we get called about are not leaks at all, and most of the real ones have nothing to do with the glass.
Here is how we sort out what is actually happening, and which fixes hold up under North Texas weather.
Condensation or a True Leak? Diagnose First
If moisture shows up as fog or fine droplets spread evenly across the inside of the glass on cold mornings — no rain in sight — you are looking at condensation. Warm indoor air hits the cold pane and sheds its humidity, especially above kitchens and baths, and especially on older single-pane units. Enough of it can drip and stain exactly like a leak.
A true leak behaves differently. It appears during or shortly after rain and favors one corner or one edge, sending a stain down the drywall of the light shaft.
There is a third impostor: blocked weep channels. Skylight frames include small drainage paths that carry minor condensation outside. When leaves and grit clog them, that water backs up indoors. Clearing the weeps is the cheapest "leak repair" there is.
Where Skylight Leaks Really Start
When it is a genuine leak, the glass is rarely the failure point. The usual suspects, in the order we find them:
- Flashing problems — a missing or improvised flashing kit, step flashing pieces out of sequence, or head flashing tucked under the wrong course.
- Debris dams — leaves packed against the uphill side, holding a puddle against seams that were never meant to sit underwater.
- Failed gaskets and cladding seals on units that have baked through decades of Texas summers.
- Underlayment shortcuts — no membrane run up the curb, so wind-driven rain finds the fasteners.
- A dead insulated-glass seal, which shows as permanent fog between the panes. That one is a failed unit, not a failed roof.
Curb-Mount vs. Deck-Mount Changes the Repair
A curb-mount skylight sits on a raised wooden box, with flashing wrapped around the curb — common on older homes and gentler slopes. A deck-mount unit fastens directly to the decking with a low profile and a manufacturer-engineered flashing kit matched to that exact model.
The distinction matters because parts and approach differ. Curb-mount units can often be swapped without disturbing the curb flashing, while deck-mount repairs call for the correct kit, not a universal approximation. Identifying which you have is step one of any honest estimate.
Skylight Leak Repair That Lasts
The durable fix for a flashing-caused leak is a reflash: strip the shingles around the unit, run waterproofing membrane up the curb or deck flange, install the proper flashing kit, and reshingle so every layer laps the right direction. Our roof repair crews treat a skylight like a chimney — a penetration that earns its own complete water-shedding system, as covered in our roof flashing repair guide.
What we will not do is bury the perimeter in roofing cement. Tar smeared over flashing cracks in a few seasons, traps water behind it, and turns a clean reflash into a messy excavation later.
When Replacement Beats Repair
Fog between the panes means the insulated seal is gone, and no amount of flashing work will clear it. Cracked cladding, chalky gaskets, and repeated hail seasons on the same acrylic dome all point the same direction: the unit is done.
Timing matters, too. If a roof replacement is on your horizon, replace aging skylights during the same project. The flashing integrates with the new shingle system, the labor overlaps instead of doubling, and the warranties start together. Old skylights reinstalled on a new roof are, in our experience, the first place that roof leaks. And if condensation keeps returning no matter what, have your attic humidity and ventilation checked — our attic inspection guide explains what to look for.
Frequently Asked Questions
How can I tell if my skylight is leaking or just condensation? Condensation appears as even fog or droplets across the inside glass on cold mornings, no rain required. A true leak shows up during or after rain, usually staining one corner or edge of the light shaft.
Can a leaking skylight be repaired without replacing it? Often, yes. If the unit is sound, stripping the surrounding shingles and installing a proper flashing kit stops most leaks. Fogging between the panes means the unit itself has failed and needs replacement.
Should skylights be replaced with the roof? Yes, whenever the units are aging. New flashing integrates with the new shingles, the labor overlaps, and the warranties line up. Putting old skylights back on a new roof invites the first leak.
What are skylight weep channels? Small drainage paths in the frame that let minor condensation escape outside. When they clog with debris, water backs up indoors and looks exactly like a roof leak, so they are worth checking first.
Skylight acting up? Call Cannon Roofing at (940) 627-1045 or request a free quote. Straight diagnosis and lasting fixes for Decatur and Greater North Texas since 1994.