It usually shows up after a big night of rain. A brown ring on the plaster around the skylight shaft, or a drip landing on the kitchen bench right under all that natural light. If you have a leaking skylight, the first thing most people do is blame the skylight itself. Often that is wrong. On the homes we look at across the Mornington Peninsula, the glass or dome is rarely where the water gets in. It is the roof detail around it.
That matters, because the fix depends completely on the cause. A tube of silicone from the hardware store will not help if the flashing is rusted through, and a new skylight will not help if the real problem is condensation.
Four places the water is usually coming from
A skylight is a hole cut in a roof that was designed to shed water. Everything that keeps it dry happens in a narrow strip around the frame. When we get up there, the leak almost always traces back to one of these.
The flashing around the upstand
Flashing is the shaped metal (or on older tile roofs, lead) that wraps the skylight frame and steers water around it and back onto the roof. It is the most common culprit by a long way. On metal roofs we see flashing that was cut short, screwed through in the wrong spot, or sealed with silicone that has long since let go. On tile roofs the tiles around the skylight get disturbed, often by someone walking on them, and the flashing underneath ends up sitting at the wrong angle. Close to the bay, salt air speeds up corrosion on any cut edge that was not treated. We cover the same failure in our guide to why flashings fail around chimneys and walls, and skylights go wrong in exactly the same ways.
Perished seals and old sealant
The rubber seals and sealant joints around the glazing break down in the sun. Once they crack, rain can track along the frame and into the shaft. This is the one case where resealing genuinely is the fix, but only once we have confirmed the flashing is sound.
Debris banked up on the high side
The top side of a skylight is a natural dam. Leaves, gum nuts and pine needles catch against the upstand, hold water, and in heavy rain it backs up over the flashing. Plenty of Mount Eliza and Mount Martha properties sit under mature trees, and this is a regular find there. Sometimes the whole repair is a clean out and a small change to the flashing so it sheds better.
Condensation that looks exactly like a leak
This one surprises people. Warm, damp air from showers and cooking rises into the skylight shaft, hits the cold glass or dome on a winter morning, and drips. It can soak the plaster just like a roof leak does. The tell is timing. If the water appears on cold, dry mornings rather than during rain, it is probably condensation, and that is a ventilation problem, not a roofing one.
Why it only drips in a storm
A lot of skylight leaks come and go. Light rain runs past without trouble, then a storm with strong wind pushes water sideways and uphill, under laps and over flashing that was only ever just good enough. That is why a skylight can stay dry for months and then drip twice in one week. If that pattern sounds familiar, our post on roofs that only leak in heavy rain explains the same problem across the rest of the roof.
What you can safely check from inside
You do not need to get on the roof to narrow it down, and we would rather you did not. From inside, note where the water appears. Staining high up the shaft on the uphill side points toward flashing or debris. Water collecting at the bottom corners of the frame often points to failed seals or a blocked drainage channel in the frame. Droplets spread evenly across the inside of the glass on a cold morning point to condensation.
If you can safely get into the roof space with a torch, look at the timber around the skylight opening. Dark water trails running down the rafters toward the shaft tell us the water is coming from above the skylight, not through it. Take a photo. It helps us more than you might think.
Reseal, reflash or replace: the cause decides
Once the cause is clear, the decision is usually simple.
- Reseal when the frame and flashing are sound and only the sealant or seals have perished.
- Reflash when the flashing is rusted, badly fitted or sitting wrong. This is the most common skylight repair we do.
- Replace when the unit itself is failing: a yellowed, brittle dome, a warped frame, or a skylight so old that fixing the flashing just moves the leak somewhere else.
What we try hard to avoid is a silicone patch over a flashing problem. It can stop the drip for a season, but it traps water against the metal and usually makes the next repair bigger. Our skylight leak repair service starts with finding the actual entry point on the roof. Then we give you a written quote that spells out which of the three jobs your skylight needs.
A small drip now is a ceiling repair later
Water getting into the skylight shaft does more than stain paint. It soaks plasterboard and the insulation around the opening, and wet framing timber around the skylight can start to rot. A small drip in spring tends to become a ceiling repair by the following winter. If you are seeing water now, put a towel or bucket under it, keep a note of when it happens, and get it looked at before the next run of storms.
Common questions about leaking skylights
Is it common for skylights to leak?
A well installed skylight with properly fitted flashing should stay dry for many years. When they do leak, it is usually down to the installation or the flashing ageing, not the idea of a skylight itself. Older units and ones fitted without proper flashing are the ones we get called to most.
Why is my skylight leaking in heavy rain but not light rain?
Heavy rain and strong wind push water sideways and uphill, where light rain simply runs past. Flashing that is a little short, debris dammed on the high side, or a gap under the tiles will only show up when there is enough water to back up over it. Leaks that come and go almost always point to the roof detail around the skylight, not the glass.
Can skylights be resealed?
Yes, and it is the right fix when the seals or sealant around the glazing have perished but the flashing is in good shape. It is the wrong fix when the flashing itself has failed, because sealant on top of bad flashing usually just delays the leak. Find the cause first, then decide.
How much does it cost to fix a leaking skylight?
It depends which job it turns out to be. A reseal is the smallest job, reflashing takes more time and material, and replacing the unit costs the most. Roof type, access and pitch also move the price. We quote in writing after inspecting the skylight on the roof, so you know exactly what you are paying for.
How long do skylights last before they leak?
There is no fixed number. It comes down to the quality of the unit, how well it was flashed, and how much sun and salt it sees. Plastic domes tend to go cloudy and brittle long before glass skylights wear out, and that is often the point where replacing makes more sense than repairing.
Is a leaking skylight covered by insurance?
Policies differ, and many treat sudden storm damage differently from wear and tear or poor installation. Read your policy and talk to your insurer before work starts. Our guide to home insurance and roof leaks covers what insurers usually want to see.
Who should I call to fix a leaking skylight?
Because most skylight leaks are really roof leaks, a roofer is usually the right first call rather than a glazier or a handyman. A roofer can check the flashing, the surrounding tiles or sheets, and the skylight itself in one visit, then tell you which repair it needs.
If water is coming in around your skylight anywhere from Mount Eliza down to Rye, we can find where it is really getting in and fix the cause, not just the stain. Take a look at our skylight repairs page or give us a call. We are available Monday to Sunday, 7am to 7pm.
