If a skylight leaks, there are two broad fixes. Reflashing keeps the existing skylight and rebuilds or replaces the flashing, the metal and sealing pieces where the skylight meets the roof. Replacing removes the skylight unit itself, usually along with new flashing. Reflashing is often enough when the glass unit is healthy and the leak is at the roof joint, while replacement makes more sense when the unit is old, fogged, cracked, rusted, or past the point where parts and seals can be trusted.
The tricky part is figuring out which problem you have, because skylight water stains can come from several places: flashing, the skylight's own seals, condensation, or a roof problem uphill of the skylight. This page explains how to think it through from the inside of the house, without climbing on the roof, and what to ask a roofer. We do not list prices, and details on specific units should come from the skylight manufacturer's instructions.
Key takeaways
- Most skylight leaks are at the flashing or where the skylight meets the roofing, not through the glass itself. Seals, condensation and roof leaks above the skylight are the other usual suspects.
- Reflashing addresses the roof-to-skylight joint. Replacement addresses the unit. Sometimes you need both.
- The age and condition of the skylight, how it is mounted, and what the roof around it looks like drive the decision.
- Replacing a skylight is often most efficient at the same time as a roof replacement, because the flashing and roofing around it are redone anyway. Our crews' view: a new roof around an old skylight can leave the weakest link in place.
- Look from inside and from the ground. Please do not climb on the roof to check a skylight.
- Water stains do not always mean a leak. Condensation can look similar and has different causes.
How do you tell where a skylight leak is coming from?
A skylight can look like it leaks when the water is actually coming from somewhere else. Think of four possibilities.
1. Flashing leak. Water gets past the metal flashing and sealing pieces that surround the unit. Stains often appear along the skylight's well (the shaft that runs from the skylight to the ceiling), especially at the top or sides after rain, and the leak tends to track with wind-driven rain.
2. Unit leak. The skylight itself fails: a seal around the glass, a cracked pane, a failed frame joint, or a deteriorating gasket. Signs include fogging between panes (a sign of a failed insulated glass seal), staining or corrosion on the frame, or drips that start at the glass edge.
3. Condensation. Warm, humid indoor air meeting a cold skylight surface can make water droplets that run down and drip. This often occurs in colder weather and in humid rooms such as kitchens and bathrooms. Condensation is not a leak, but it can stain and mold a well. The fix may involve ventilation or the type of glass, not flashing.
4. A leak somewhere else. A leak from a nearby wall, a vent, a valley, a chimney or even higher on the roof can run along framing and show up at the skylight. Our guides on how to find a roof leak and what a roof leak looks like cover the general detective work.
Observations you can make safely from the inside and the ground:
- Does the stain appear only during or after rain, or also on cold mornings without rain? (Rain only suggests a leak; cold mornings suggest condensation.)
- Does the staining show at a particular side of the well?
- Is there fogging between the glass panes?
- Is there rust, peeling paint or soft drywall around the well?
- Are there stains in the attic around the skylight shaft, if an attic is accessible and safe to enter?
- Does the skylight look old, discolored or cracked from the ground?
Take dated photos. They help you and your roofer. A roofer can then inspect the roof side safely.
What is skylight flashing?
Flashing is the system of metal and sealing materials that directs water around a roof penetration. A skylight usually has a flashing kit or custom flashing around its perimeter. In general terms:
- Sill (bottom) flashing sits at the lowest edge of the skylight and sheds water out onto the roof.
- Side flashing runs along the sides, often woven with the shingles in a stepped pattern, which is what roofers call step flashing.
- Head (top) flashing sits above the skylight and directs water around the sides.
- Some roofs also have a saddle or cricket above a skylight on a steeper slope. It is a small peaked structure that diverts water around a larger obstruction.
Skylights come in different mounting styles. A curb-mounted unit sits on a raised frame built on the roof, and is typically flashed to the curb. A deck-mounted unit sits close to the roof surface with a flashing kit designed for it. Which type you have affects the repair, and the manufacturer's instructions for your model apply. Our overview of what flashing is explains the basic idea, and the same vocabulary comes up in our page on chimney flashing repair versus replacement.
What does reflashing a skylight involve?
Reflashing means the roofer rebuilds the weatherproofing around the skylight without replacing the unit. The scope depends on the roof and the skylight, but in general it may include:
- Removing shingles around the skylight to expose the old flashing and deck.
- Inspecting and repairing any damaged decking or framing near the opening.
- Installing new underlayment, self-adhering membrane and flashing pieces to the manufacturer's detail.
- Weaving new step flashing with the shingles and installing head and sill flashing.
- Replacing or reinstalling the shingles around it.
- Sealing as the manufacturer's instructions allow (sealant is a supplement, not a substitute for proper flashing).
Reflashing often works well when the skylight unit is sound, the leak is at the flashing, and a flashing kit or custom flashing is available for that skylight model. It is less likely to be the right answer when the unit itself is failing or when the old model's parts are no longer available.
What does replacing a skylight involve?
Replacement removes the existing unit and installs a new one, along with a new flashing kit or custom flashing sized for it. The work typically includes the roof-side steps listed under reflashing, plus interior work at the light well and ceiling opening if the new unit differs in size or the well is damaged. A new skylight may differ in glazing, venting, operation (fixed, manual or powered), shades and features, and manufacturers publish instructions for each model (check the manufacturer’s specifications).
If a skylight is being replaced with an identical or compatible size, the job can be simpler. If the size changes, framing may need to be modified, and it is worth asking whether permits or inspections are needed. Requirements vary by city and county; ask your building department or roofer.
How do reflashing and replacing compare?
Use this as a checklist for conversations. It describes general tendencies, not guarantees.
| Topic | Reflash the existing skylight | Replace the skylight |
|---|---|---|
| What changes | Flashing and surrounding roof layers | The skylight unit plus its flashing |
| Best when | Unit is sound; leak is at the flashing or roof joint | Unit is old, fogged, cracked, corroded or leaking through itself |
| Condensation problem | Does not fix it | May help if a different glazing or venting is chosen; ventilation may also matter |
| Interior disruption | Usually limited | May involve the light well and ceiling opening |
| Parts availability | Needs a compatible flashing kit or custom flashing | New unit and matching flashing kit are chosen together |
| Efficiency and features | Same as existing | Can change glazing, venting, shades and operation |
| Cost relationship | Usually lower; ask for an itemized estimate | Usually higher; includes the unit |
| Timing with a roof replacement | Works, but may be redone later if the unit ages out | Often cleanest done together with the roof, so the roof and skylight flashing are built as one system |
| Warranty | Depends on workmanship warranty and any part warranties | New unit has its own manufacturer warranty; read it (check the manufacturer’s specifications) |
| Risk | Underlying unit problems may remain | Cost, and a new unit's installation still depends on good flashing |
"Usually lower" and "usually higher" are relationships, not prices.
Which should you choose: reflash or replace?
A set of questions that tends to settle it:
- How old is the skylight, and what condition is it in? Fogging between panes, cracked glazing, rusted frames, brittle gaskets and discoloration point toward replacement. A younger unit in good shape is a reasonable reflash candidate.
- Where do you think the leak is? If the evidence points to the roof joint (rain-only leaks, staining at the well edges), a flashing repair makes sense. If the glass edge or frame is the problem, the unit needs attention.
- Is it condensation? If stains appear on cold mornings, in humid rooms and without rain, consider ventilation, humidity and glazing before paying for flashing.
- What about the roof around it? If shingles are old or the roof is near replacement, it is more efficient to address the skylight with the roof. A flashing repair on a roof that is about to be replaced may be a short-term fix.
- Are replacement parts or kits available? Older models can be hard to match. Ask the roofer and the manufacturer.
- Do you want different features? If you would like a venting skylight, different glazing or a shade, replacement is the time.
- What does the manufacturer say? The installation instructions for the specific skylight and flashing kit are the standard to follow.
- What does your budget allow? Ask for the reflash and replace options as separate itemized lines.
Our crews' view: if the roof is being replaced anyway and the skylight is old, replace it with the roof, so the flashing is built as part of the new system. If the roof has years left and the skylight is healthy, a proper reflash is a reasonable repair. A bead of sealant alone is a bandage, not a fix.
What mistakes do homeowners make with skylight leaks?
- Assuming the skylight is the leak. Always rule out another source and condensation.
- Relying on sealant alone. Caulk can slow a leak for a while. It does not replace flashing built to the manufacturer's detail.
- Climbing on the roof to look. It is dangerous, and walking on a roof can damage shingles. Look from inside and the ground.
- Waiting. Water traveling along the shaft and framing can cause rot, stains and mold before it becomes obvious.
- Reflashing a roof that needs replacement. Fixing one spot in a roof near the end of its life can be money spent on a short-term fix; get an honest assessment.
- Replacing without fixing flashing. A new skylight on bad flashing will leak too.
- Ignoring the interior. Wet insulation, stained drywall and mold are part of the repair scope.
- Not asking about permits. Changing skylight size or framing may involve rules that vary by city and county.
Frequently asked questions
Why is my skylight leaking? Common causes are failed or poorly installed flashing, aged seals and gaskets on the unit, condensation, or water entering above the skylight. A roofer can identify the likely source.
Can a skylight leak be fixed with caulk? Sealant may slow a leak, but flashing is the real defense against roof water. We view caulk as a temporary measure. Ask your roofer to inspect before relying on it.
How can I tell condensation from a leak? Condensation usually appears on cold, humid days with no rain and can drip from the glass or frame. Leaks tend to track with rain and wind. If you are unsure, note when it happens and tell your roofer.
How long do skylights last? It depends on the model, materials and exposure. Manufacturers publish information; ask about the specific unit (check the manufacturer’s specifications).
Should I replace the skylight when I replace the roof? Often yes if the skylight is old or has leaked, because the flashing is built as part of the new roof. If the unit is in good shape, reflashing it with the new roof may be enough. Ask your roofer to inspect first.
Can any roofer reflash any skylight? Flashing should follow the manufacturer's instructions for the specific skylight. Ask a roofer how they handle your type and whether they have experience with it.
Will my homeowner's insurance cover a leaking skylight? Policies differ. Many policies treat wear and tear differently from sudden storm damage, and we cannot say how yours would apply. Read your policy and ask your agent.
Is it safe to look at the skylight from the roof? We recommend you do not. Look from inside and the ground, take photos, and let a roofer inspect from the roof.
Need a skylight looked at?
We can look at your skylight from inside and outside, work out whether the problem is flashing, the unit or something else, and give you reflash and replacement options on a written, itemized estimate. An inspection tells you about the roof; it does not predict your insurer's decision, and we will not tell you otherwise. Call Total Roof Protection OKC at 405-415-5841, or see our roofing services.