Q & A - Repairing a Leaking Skylight

There are yellow water stains on the ceiling, is it because of my leaky skylight?

Elizabeth asked, "I have yellow water staining the ceiling near a recessed light. I had a roofer look at my roof and he said the roof was ok. He suggested to “boot insulate” around my six can lights at a cost of $1,000. My roof is 30 years old with a skylight near the leak. What do I do?"

Just because you see water stains in your ceiling near a light does not mean the moisture intrusion is because of the light. Water can flow sideways and downwards to seek a low area and when it finds a hole, like a light, it drips out at this spot. The leak, in my opinion, is probably something else since these lights have been in place for many years and have never leaked before. I am not sure what it means to “boot insulate” so I will leave that comment alone.

Most skylights leak because of poorly installed flashings.

Your 30-year-old roof is showing signs of age, but the main point of interest for me is the large skylight and it’s flashing. From my perspective, it looks to have a side flange on top of the shingles and is very near the leak area. Skylights installed on steep-slope roofs like yours should have step flashings woven into every course of shingles with an upper and lower saddle type flashing. Since this skylight also has been on your roof a long time it is hard for me to say this is the problem since I am thousands of miles away. Having repaired many skylights in my life installed wrong like this one, I would start looking here first. Flashed like this, they all seem to leak right near the side of the skylight and that is right where your ceiling stains are.

My next point of interest is the chimney that is on the edge of the roof. It has a long side and it also needs step flashings, one per every course.

My suggestion is to hire a licensed roof inspector and get another opinion.

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