Why is my skylight leaking?

Most skylight leaks come from the flashing around the skylight, not the glass. Water gets in where the flashing is loose, rusted, or was sealed with caulk instead of being woven in with the shingles. If the drips show up on cold, dry days, it may be condensation on the glass, not a roof leak at all.

If you want me to take a look, text a picture to 443-900-4815 or call the same number. I'm James. I've worked on roofs around Baltimore City and Baltimore County for 24+ years, and I'm licensed and insured, MHIC #154344.

Where does the water get in?

• The flashing. The metal pieces around the skylight frame that send water around it and back onto the roof. When they loosen, rust, or were never lapped under the shingles, rain runs in at the edges. See roof flashing repair.
• The uphill side. Leaves and debris pile up above the skylight and hold water against it. In a heavy rain, that water backs up under the flashing.
• Old caulk or tar. A lot of skylights get "fixed" with a bead of caulk or roofing tar. It works for a season or two, then cracks and lets water in again.
• The curb. On many skylights the frame sits on a wood box built up off the roof. If water has been getting in for a while, that wood can rot, and the flashing has nothing solid to hold onto.
• The skylight itself. A cracked pane or a failed seal between the panes can leak or fog up. That is less common than a flashing leak.

Is it a leak or condensation?

Here's how to tell them apart:

• Drips only when it rains, or right after: most likely a leak at the flashing.
• Water at one corner or one side of the opening, often the uphill side: most likely a leak at the flashing.
• Drips on cold, dry mornings, with water beaded across the glass: most likely condensation. Warm, damp air inside the house hits the cold glass and turns to water.
• Fog or moisture between the two panes: the seal in the skylight has failed.

Condensation isn't a roof problem, so new flashing won't fix it. If we come out and it turns out to be condensation, I'll tell you that.

What happens if I leave it?

A small skylight leak tends to get worse. The water soaks the wood around the opening, which rots the curb and the roof deck around it, and then the flashing can't be fastened down well. Fixing the flashing early is usually a much smaller job than fixing rotted wood later.

What we do

1. Look at the skylight from the roof when it's safe, including the flashing on all four sides and the shingles around it. On a steep roof I can use the drone. I'm an FAA-licensed drone pilot.
2. Find where the water is really getting in, not just where it drips inside.
3. Send you pictures of what we found, with a price before any work starts.
4. Fix the source: reflash the skylight, lap the flashing in with the shingles the right way, and repair the curb and the wood around it when it's soft.

You can text me at 443-900-4815 with a picture of the skylight and where it's dripping, or call the same number.

Skylight leak questions

Why does my skylight only leak in heavy rain?

Heavy or wind-driven rain backs up behind debris on the uphill side and pushes water under loose or short flashing. A light rain runs off before it can get in. If it only leaks in a hard or windy rain, here's why a roof leaks only in heavy rain.

Can a leaking skylight be fixed without replacing it?

Usually, yes. Most skylight leaks are the flashing, and the skylight can stay. If the glass is cracked or the seal between the panes has failed, the skylight itself may need replacing, and we'll tell you what we see.

Can I just put caulk around my skylight?

Caulk can slow a leak for a short time, but it cracks in the sun and the cold. Flashing that is lapped in with the shingles sheds water on its own, without depending on caulk.

How do I know if my skylight is leaking or it's condensation?

A leak shows up during or right after rain, usually at one side or corner. Condensation shows up on cold, dry days as water beaded across the glass.

How much does it cost to fix a leaking skylight?

It depends on the size of the skylight, how steep the roof is, and whether the curb or the wood around it has rotted. You get a price before any work starts.