# Skylight Leak



## bender_dundat (Feb 20, 2011)

The older Velux skylights used a rubber gasket/membrane to seal between the metal frame and the glass. Heat and time caused this rubber to harden and become brittle. When replacing the roof, if you move the skylight much thereby flexing the frame, it can cause this brittle gasket to crack eventually leading to a leaky skylight that has nothing to do with the flashing.

As someone else said, we give the Homeowner several options when they have a skylight. We'll replace it with a new one or we won't guarantee a leak around it. Those old skylights had a 5 year warranty. How can you warranty a product already out of the manufacturer's warranty?


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## pm_sup (Feb 19, 2007)

I'm going to ressurect this old thread, just in the interest of keeping things together, in case someone else does a velux skylight search.

I redid our roof in the summer 5 months ago. I am a contractor, but not a roofer. Likely I went overkill on a lot of my step flashing areas, and valleys by using eaves protection everywhere under the flashings and over the eaves. 4.5/12 pitch Harmony shingles

(yes I did caulk all the exposed nails)

We had a couple days of high wind and rain, and I noticed a brown stain on the ceiling on one side of the drywall under the skylight.

We've had lots of rain, and snow, but not the combination of wind and rain.

Because the velux has a built in curb, I used eaves protection style peel and stick under the flashings and step flashing, before redoing the asphalt and flashings.

I checked the attic expecting to find it soaked, but appears that it is leaking on the bottom corner only, on one side.

Is it possible that the wind was driving the rain under the cap flashing, and behind the step flashing?

I don't really want to caulk the s#!t out of it. 
I don't want to break all the shingles (even though I have extra ones) Once the weather warms up a little I was thinking of using some more peel and stick, and tuck it further up and behind the cap flashing on the skylight before reinstalling the shingles and step flashings.

I am assuming it's either the rain going under the cap flashing. A bad install by me at the lower corner, or the skylight gasket leaking at the bottom corner.

The skylight it west exposure, so I don't think the gasket gets baked by the sun too much. Skylight is probably 15 years old and a 4 x 4 vented unit.

Thanks for any suggestions


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## All City (Feb 22, 2013)

I would remove all shingles from around the skylight and redo the ice and water with a NEW flash kit. You could water test your flashing work first and soak the skylight second to confirm if it's your flashing or the skylight.


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## AndyWRS (Sep 12, 2010)

Sounds like you went over kill. Be a shame to pull it up just assuming its the flashing.

Fixed or Openable skylight - possibly not closed tight enough?

Check it for cracks, you never know. 

Take the lid off and see if there is staining on the top of the curb...this will indicate the skylight is the issue vs the flashing / roofing.

Water test the corner you suspect.


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## pm_sup (Feb 19, 2007)

Just a little follow up, in case it helps someone else.

Background; When I got a quote from one of my roofing contractors, I work with on multifamily jobs, I told him that I had two skylights, and asked if he replaced all the step flashing.

He said; no we just tuck the new shingles under the flashing.

So being a dummy, I did that, even though I thought I was being really careful.

AND for the most part I did a good job.

Problem came at the Velux skylight, which has a really short curb. The bottom and top corner step flashings were nailed on the vertical curb, under the skylight curb flashing.
No way to really do thes properly, without taking up the curb flashing.

I was in a rush, it was the last part of the roof, and I was getting tired (working nights and weekends to redesign a lot of the framing - built 4 dormers and a turret - and reroof)

When I went up on the roof yesterday, I pretty much saw where the problem was.

The bottom step flashing had been bent and butchered during my reroof.
Consequently there was a pinky finger sized kink and opening, right at the bottom corner of the skylight. Right where the water is going to drip down from the skylight.

Yeah so I did it right, and overkilled it.

Pulled off a couple shingles, pulled off the curb flashing, denailed and replaced the buggered step flashing.

Before I replaced it, I added a few pieces of peel and stick, for extra measure, including wrapping the bottom corner.

Yeah, after I put it all back together, it is a night and day difference.

I suppose I could have just caulked the $#it out of it, and fixed it that way. Probably what my roofer would have done.

BUT when the wife asks me, if I really fixed it, when it's pissing rain, I don't want to be keeping my fingers crossed behind my back


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## LCG (May 30, 2011)

pm_sup said:


> BUT when the wife asks me, if I really fixed it, when it's pissing rain, I don't want to be keeping my fingers crossed behind my back


Chicken!


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## Tom M (Jan 3, 2007)

I would remove the counter flashing and look around. The older velux had face screws in the cap flashing that would become a problem. If your skylight is new or old, under the counter flashing you will find a silver plate with face screws around the perimeter which holds the glass in place. Check these with a hand screw driver. Most installers never think to bother looking at this but I have had one leak in a bottom corner because of it.

If nothing seems out of place then dismember the flashing. I have also seen a good install leak because someone shot long nails in the finish trim from inside.


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## All City (Feb 22, 2013)

pm_sup said:


> Just a little follow up, in case it helps someone else.
> 
> Background; When I got a quote from one of my roofing contractors, I work with on multifamily jobs, I told him that I had two skylights, and asked if he replaced all the step flashing.
> 
> ...


Nice job, but why did you hire that roofer?


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## Dallas-Roofing (May 12, 2013)

There are many situations where the skylight itself could be the cause of the leak. Take a good close look at skylight from inside the house. You can also have someone spray water with a hose while your inside locating the leak. Another spot I would look at is the ridge and slope above the skylight. A lot of times, water will travel down the decking before it penetrates through the ceiling. 

Devin Mahdi
DFW Roofing Company


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