New Skylight leaking - low pitch roof


Just had entire roof replaced a few months ago, including skylight. The new skylight just leaked during recent rainstorms. Roof pitch is 10 degrees. What went wrong here?

Skylight Installation



You have the wrong style skylight. Low slope roofs should have curb mounted units, much more reliable.


Did your “fix” have any effect?


The roofer just made that modification - we’ll find out over the next couple of days as some heavy rains are in the forecast.


It looks as though the roofer installed the skylight like it would be done on a pitched roof, as you can see that doesn’t work in this situation.

The cladding on the skylight needs to be removed and the entire skylight needs to be wrapped in the membrane used for the roof.

The bottom of the skylight is not to be exposed in this scenario.

Like Patch said it is not the ideal skylight for this application but it can be made to work.


It looks like your roofer tried to do right, just got it a little wrong if I am seeing what I think I am. It appears that he soldered a copper curb around a sloped roof deck mount skylight, rather than building a curb and wrapping that in copper. Not sure why he left the bottom exposed like you would on a shingle roof.

The copper flange should have been all set in a bed of flashing cement on top of the membrane, nailed securely, primed, then flashed in all the way around with strips of membrane.


That fix is a band aid, it may keep the water out temporarily, but that mastic/tar is typically used on certain leak repair and will eventually dry out and start cracking. It’s any easy fix, he needs to remove the copper and use torch a curb flashing goes up and over the lumber that the skylight is sitting on. Hopefully the skylight isn’t too snug.


Titan is right about the mastic/tar.
Make sure your house insurance, particularly storm damage, is kept up to date.
Best of luck