Most skylight leaks come from failed flashing, perished seals or cracked glass, and condensation is often mistaken for a leak. Skylight leak repair usually means resealing, replacing the flashing, or replacing the glass; an old or poorly installed skylight may need to be replaced altogether. Limit the damage from inside, then have a qualified glazier or roofer inspect it.
This guide helps Sydney homeowners determine whether it’s a leak or condensation, safely narrow down the cause from inside, understand what each repair involves and what drives the cost, and decide whether to repair or replace.
What to Do Right Now if Your Skylight Is Leaking
Start by limiting the damage from inside the house. Don’t go onto the roof: skylights are fragile, and a fall can be fatal.
- Catch the water. Put a bucket or towels under the drip and move furniture, rugs and electronics away.
- Check the ceiling. If the plasterboard around the skylight is sagging or bulging, keep clear of it; it can hold water and collapse.
- Turn off nearby electrics if water is near light fittings, downlights or a motorised skylight, and have an electrician check them before using them again.
- Close a vented skylight if it’s open, using the pole, remote or wall switch.
- Photograph everything: the drip, ceiling stains and the weather at the time. Photos help your glazier and any insurance claim.
- Book an inspection before the next heavy rain, especially if the stain is spreading.
Is It a Leak or Condensation?
If water appears only when it rains, it’s almost certainly a leak. If droplets form on the inside of the glass on cool mornings, after showers or while cooking, and the glass looks fogged, it’s more likely condensation. Water trapped between two panes of double glazing means the unit’s seal has failed.
| What you notice | Likely cause | What it usually needs |
| Drips only during or after rain | Leak through flashing, seals or glass | Inspection and repair |
| Stain spreading on the ceiling around the skylight shaft | Water enters at the roof and travels down the lining | Inspection; flashing or seal repair |
| Droplets on the inside of the glass on cold or humid days, with no rain | Condensation | Better ventilation; possibly double glazing |
| Fog or water between the two panes | Failed double-glazed unit seal | Glass unit replacement |
| Water only when the vented skylight has been opened | Vent not closing fully or worn seals | Clean, adjust or replace seals |
| Rattling, visible crack or chip in the glass | Damaged glass | Glass replacement |
Condensation happens when warm, moist air meets cold glass. It’s most common over bathrooms, kitchens and laundries, and with single-glazed skylights. Running the exhaust fan, opening a window while showering or cooking, and keeping the skylight’s weep holes clear all help. If it keeps happening, replacing single glazing with a double-glazed unit is the long-term fix.
Skylight Leak Diagnostic Checklist
Work through these checks from inside the house and from the ground. Note what you find; it helps your glazier diagnose the fault faster and can reduce inspection time.
- ☐ When does it drip? Only in rain, only in heavy or wind-driven rain, or on dry days too?
- ☐ Where exactly is the water? On the glass itself, at the frame edge, running down the shaft walls, or as a stain on the ceiling beyond the skylight?
- ☐ Which side of the skylight? Water at the top (uphill) edge often indicates flashing or debris; water at the bottom edge indicates blocked drainage or seals.
- ☐ Is the inside of the glass wet, but the frame dry? That suggests condensation rather than a leak.
- ☐ Is there fog or water between the panes? That means the double-glazed unit’s seal has failed.
- ☐ Can you see a crack, chip or star break in the glass? Look from directly below with a torch.
- ☐ Is it a vented skylight? Check that it closes fully and that nothing is caught in the seal.
- ☐ From the ground, can you see anything on the roof? Use binoculars or a phone zoom to look for leaves piled against the skylight, cracked or slipped roof tiles, lifted metal sheeting or a missing section of flashing.
- ☐ Has there been a recent storm or hail? Note the date; it matters for insurance.
- ☐ How old is the skylight, and who installed it? Check for any warranty paperwork.
If you can’t pinpoint the source, that’s normal. Water can enter at one point on the roof and travel along the framing before it drips somewhere else. A qualified tradesperson can water-test the skylight safely from the roof using proper access equipment.
7 Common Causes of a Leaking Skylight
1. Failed or Poorly Fitted Flashing
Flashing is the metal (or metal-and-rubber) collar that directs water around the skylight and back onto the roof. If it was fitted badly, has corroded, or has been dislodged by wind or by someone walking on the roof, water gets under it. Skylights mounted flat on the roof deck depend almost entirely on their flashing, while those set on a raised upstand (curb) have an extra line of defence. Flashing faults usually show up as leaks at the top or sides of the skylight during heavy or wind-driven rain.
2. Perished Seals and Gaskets
Silicone seals and rubber gaskets hold the glass in the frame and keep water out. Sydney’s strong UV and heat break them down over time, causing cracking, shrinking or lifting. Perished seals typically leak at the glass edge and get gradually worse.
3. Cracked or Damaged Glass
Hail, falling branches and thermal stress can crack skylight glass, sometimes with a fine crack that’s hard to see from below. Skylight glass must be safety glass that meets the rules in AS 1288 for sloped overhead glazing, which allows laminated safety glass and, in limited cases, toughened safety glass. A cracked panel should be replaced by a glazier, not sealed over. Silicone on a crack is a short-lived patch that hides the problem and can leave the panel weaker.
4. Damaged Roof Around the Skylight
The skylight can be sound while the roof around it isn’t. Cracked or slipped tiles, perished pointing, or loose or rusted metal sheeting near the skylight allow water to enter, which then runs into the skylight shaft. Storms often cause this kind of damage.
5. Blocked Drainage and Debris
Leaves and dirt build up on the uphill side of a skylight and around its edges, causing water to pool and back up under the flashing. Many skylights also have small weep holes or a condensation channel that drains moisture outside; when these block, water overflows inside.
6. A Vented Skylight That Won’t Close
Opening skylights can let water in if they’re left open, if debris prevents them from closing fully, or if their seals or hinges wear out. Motorised units can also lose their rain sensor or close incompletely. If water appears only after the skylight has been opened, start here.
7. Installation Faults
Some leaks trace back to the original installation: a skylight fitted at too low a pitch to drain, a home-made flashing instead of a matched kit, a poorly sealed upstand, or a frame that wasn’t fixed square. These leaks often start within the first few years and come back after each patch until the installation is corrected.
How a Leaking Skylight Is Repaired
The repair depends on what the inspection finds. Most leaks are fixed by clearing debris and resealing or replacing flashing; cracked glass and failed double glazing need the glass replaced; and an old skylight or one that was installed poorly is often better replaced. Here’s what each repair involves, from the smallest job to the largest.
| Repair | When it’s needed | What’s involved |
| Clear debris and drainage | Leaves or dirt blocking water flow or weep holes | Clearing the roof around the skylight and unblocking the drainage |
| Reseal | Perished or lifting silicone and gaskets | Removing old sealant, cleaning, and applying new UV-stable seals |
| Vent adjustment or seal replacement | Vented skylight not closing or seals worn | Cleaning, adjusting hinges or motor, replacing seals |
| Flashing repair or replacement | Damaged, corroded or poorly fitted flashing | Lifting surrounding roofing, fitting new matched flashing, and restoring the roof |
| Glass replacement | Cracked glass or failed double-glazed unit | Removing the panel and fitting new safety glass or a new sealed unit |
| Roof repair around the skylight | Cracked tiles or damaged sheeting nearby | Replacing or re-bedding tiles or sheeting, often alongside flashing work |
| Full skylight replacement | Old unit, repeated leaks, damaged frame or installation fault | Removing the old skylight, correcting the opening and installing a new unit |
How Much Does Skylight Leak Repair Cost?
There’s no set price for skylight leak repair, because the cost depends on what’s causing the leak and how hard the skylight is to reach. A reseal or debris clean-out on an accessible single-storey roof is a much smaller job than replacing flashing, glass or the whole unit. For an accurate price, request a free, no-obligation quote.
The main factors that affect the cost are:
- The cause and the repair needed: resealing costs less than new flashing; replacing the glass costs more; a full replacement is the largest job.
- Access and roof height: a steep or two-storey roof needs more safety equipment and time.
- Skylight type: vented and motorised skylights have more parts to service than fixed ones.
- Glass type and size: double-glazed, laminated, Low-E or custom-sized glass costs more to replace.
- Hidden damage: rotted framing, wet insulation, or damaged ceiling lining found during the repair adds work.
- Roof material: working around tiles, metal sheeting or a flat membrane roof involves different methods.
Ask for a written quote that names the cause, the repair and what’s included. Catching a leak early usually keeps it at the smaller end of the scale, before water damages the ceiling and framing.
Should You Repair or Replace a Leaking Skylight?
Repair it if the skylight is otherwise in good condition and the fault is limited to seals, flashing, debris or a single glass panel. Replace it if it’s leaking repeatedly, the frame is corroded or rotted, it’s single-glazed and causing condensation, or the original installation is at fault.
Repair is usually the better choice when:
- The skylight is relatively new, and this is the first leak;
- The frame and glass are sound apart from the identified fault;
- The leak is from debris, a seal or a localised flashing problem.
Replacement is usually the better choice when:
- The skylight has leaked before and been patched more than once;
- The frame is corroded, rotted or out of square;
- The skylight is old, single-glazed and causing heat or condensation problems;
- The installation itself is faulty, such as the wrong pitch or home-made flashing.
Replacing a leaking skylight is also a chance to upgrade to double-glazed or Low-E glass. Learn more about skylight replacement in Sydney.
Why Skylight Leak Repair Isn’t a DIY Job
The biggest risk with a leaking skylight isn’t the water; it’s getting onto the roof to look at it. SafeWork NSW warns that skylights should be treated as non-trafficable unless certified otherwise, and falls through skylights and fragile roofing have caused serious injuries and deaths in NSW. Wet tiles and metal roofs are also slippery.
DIY fixes also tend to make things worse. Silicone smeared over flashing or a crack can trap water, hide the real fault and make the eventual repair harder. Lifting tiles or flashing without the right materials can open new leaks.
A qualified tradesperson has access to the equipment, matched flashing kits and safety glass to fix the cause rather than the symptom, and can tell you whether the fault is in the skylight or the roof around it. In NSW, residential glazing work over $5,000 (labour and materials, including GST) must be done by a licensed glazing contractor, so ask any installer for their licence number.
Talk to Majestic Glass About Your Leaking Skylight
Majestic Glass’s skylight specialists can talk you through your options for a leaking skylight, replace damaged skylight glass, or install a new double-glazed skylight if repair isn’t worthwhile. Call 1800 452 946 or request a free, no-obligation quote, and include photos of the leak and the ceiling to help us advise you quickly.
Frequently Asked Questions
Is a Leaking Skylight Urgent?
Yes, treat it as urgent. Even a small leak can soak the insulation, stain and weaken the ceiling plasterboard, rot the timber framing, and encourage mould. If water is near light fittings or a motorised skylight, there’s an electrical risk too. Book an inspection before the next heavy rain.
Does Home Insurance Cover a Leaking Skylight?
It depends on the cause and your policy. Sudden damage from a storm or hail is often covered, but damage from gradual wear, lack of maintenance or faulty artistry is commonly excluded. Check your product disclosure statement, photograph the damage, and contact your insurer before arranging repairs.
Why Does My Skylight Only Leak in Heavy Rain?
Heavy or wind-driven rain pushes water sideways and upwards, past flashing and seals that cope with light rain. Overflowing gutters or debris piled against the skylight can also send water where it normally wouldn’t go. Leaks that only appear in storms usually point to flashing, seals or drainage.
Can a Leaking Skylight Be Fixed From Inside?
Usually not. Most leaks start at the roof, so the flashing, seals or glass must be repaired from outside. Sealing the inside of the shaft only hides the water. Condensation problems are the exception: better ventilation, clear weep holes or double glazing deal with the cause.
Do Tubular Skylights Leak?
They can. Tubular skylights usually leak where the tube meets the roof, through a damaged flashing collar or a perished seal around the dome. Because they’re smaller, the repair is often simpler, but the same rule applies: the fix has to happen on the roof, by someone with safe access.
Stop a Skylight Leak Before It Spreads
A leaking skylight rarely fixes itself. Limit the damage from the inside, work through the checklist to tell a leak apart from condensation, and have a professional inspect the flashing, seals, and glass before the next downpour. Small faults caught early are usually simple repairs; leaks left for months can mean ceiling, framing and full skylight replacement.