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We recently discovered a leak manifesting itself with stains in our ceiling. It likely happened a few days ago when we had about 2-3" of rain overnight. We have never had a leak before, and the roof itself was installed 6 years with new sheathing. Since our solar panels are mounted close to the affected spot, my initial hunch was that the leak was from a roof penetration, but upon inspection I am unsure if that is the culprit. Because the rafters are old and have prior moisture marks, I can't determine the exact spot of the water penetration into the attic.

I do see that there is a visible gap between two sheathing OSB pieces where the one piece of rafter meets another, and the second piece is a bit higher (see photo #1 below). This manifested by a slight depression or dip in shingles above (photo #2). This is the general area of the leak (within a foot or so) but I am unable to see any gaps or issues with the shingles, so what should the procedure be to fix this issue? Should we run a hose and find the spot? And for the fix, should we just "unlock" shingles in the general area and apply sealant?

Note: There are no water pipes, HVAC or other water related stuff in the attic.

Height difference in OSB boards as seen from the attic

Slight dip where the sheathing pieces meet on the roof

Stains on ceiling. Biggest stain on the right is beneath the gap in the sheathing.

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    where are the stains that cause concern? can you add red circles or something?
    – depperm
    Commented Apr 13, 2022 at 15:28
  • That dip showing in the second picture might hold enough water to run back underneath the shingles. Maybe if can raise that section roof decking up or down it will fix it.
    – crip659
    Commented Apr 13, 2022 at 15:33
  • @depperm: No stains are visible in roof sheathing, but there was water on the insulation and stains on our ceiling drywall.
    – 0pt1m1z3
    Commented Apr 13, 2022 at 16:41
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    A post isn't the right way to fix that. If it is the cause of the problem (and I have doubts), you'd simply drive some shims under the sheathing to taper out that offset. Show us an exterior photo with more context, please. I don't have a good sense of the scene.
    – isherwood
    Commented Apr 13, 2022 at 18:16
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    The roof pitch looks fine, I have found leaks to travel as much as 15’ from the origin and I could not see it! How did I find it a FLIR camera, a FLIR camera sees things we cannot the water running in a crack or sistered board they have showed up really well infact I purchased my first FLIR camera that attaches to my IPhone a quite while back and a pro model maybe 2 years ago I use them for finding roofing leaks , bad connections in electrical panels and receptacles, hvac leaks Why the long list when some see the cost to possibly find a leak they pass but all the other things they are worth it
    – Ed Beal
    Commented Apr 13, 2022 at 19:12

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Always look upslope of the leak below. Water can run along roof framing for great distances, so the leak could be anywhere higher up the roof, rather than directly above the wet ceiling below.

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  • Thanks. We may have to wait for another rainy day then and look at that rafters in that area. Unfortunately, there are no visible moisture marks on the rafters or sheathing in that general area that would show travel of water from higher up. It also wasn't a dripping / heavy leak and so it took us a couple of days to even notice the stains.
    – 0pt1m1z3
    Commented Apr 13, 2022 at 19:45
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    You might try dusting the area (framing/sheathing) with something that would leave a track to show water has been there. Not sure what would work best for that. Chalk dust, maybe?
    – Ecnerwal
    Commented Apr 14, 2022 at 0:06
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    If you have (relatively) easy access to the roof, you could induce that rainy day with a garden hose. Just let it run for an hour or so on the suspected area, if possible with a hosing motion so as to cover a wider area.
    – MiG
    Commented Apr 14, 2022 at 7:45

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