What is the cause of the roof leak?

This is a 2004 home in the CA mountains. It is a pre-listing inspection for the seller.

The roof is 3-tab asphalt shingle, approximately 18 years old. When it rains, there is an active water leak at the end of the porch roof beam-second from the end, immediately to the right of the wood stove. The thermal camera image shows a potential damp spot (or change in emittance) immediately above (roughly parallel to the stove vent), along the top of the beam, and then down the side of the beam, although the water stains are only at the end of the beam. Everything is dry now (at the time of inspection) using moisture meter.

The only roof penetrations directly above that location are two DWV pipes 20’ higher up the roof over the main house. They looked good. There is a short eave on the outside that end of the porch. No damage to the fascia. There are no visible flaws in the roof covering immediately above the leak location.

The homeowner applied roofing mastic to everything in sight: the shingle valleys, the stove chimney, skylights, and so forth. It broadcasts “roof problems,” but he did not stop the leak.

Need some input. Is the thermal image indicating the leak is right there next to the stove vent? Or is the leak possibly coming from somewhere else?

As far as recommendations, I am thinking the DIY attempts are repairs are going to scream roof problems to potential buyers. So, the seller needs to definitely find the source and fix the leak, or replace the roof. Thoughts?

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Were you hired to find the leak and fix it?

The seller needs to hire a roofing contractor to fix the leak instead of playing DIY.


Likely coming in from this crappy roof repair. But as Simon said the seller needs to get a roofing contractor to determine what needs to be done and make the repairs.


Send me the raw radiometric scan to RequestAnInspection@gmail.com and I will analyze it with my software.

We are likely not looking at the right things here.
That looks like a shadow on the roof reducing heat transfer.


Was anything wet while you were there?
There are stains in the wood, but they never go away.


My question to you is… if “everything is dry now”… what exactly is the Thermal camera detecting as being a cooler temp?? Water moisture? Air movement? My WAG is there is hidden moisture/rot other than the initial cause, and a qualified contractor needs to investigate which may involve destructive methods to discover the true damages.

Edit: I see David just posted. Absolutely take him up on his offer. IMO, there is no other member on this forum with more knowledge about these things related to Thermal.


Nothing wet - dry as a bone. Going by the homeowner that the leak was not fixed. I like your observation that it could be simply a shadow from the chimney. I will send the thermal image.

No. Not hired to find the source of the leak or fix it and have my standard “Further evaluation and correction by a roofing specialist is recommended” is in the report. I was just trying to narrow it down a bit, as a courtesy and for my edification. A roofing contractor is most likely to recommend a new roof.

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I like David’s answer that it could be just the shadow from the chimney. Why didn’t I think of that! Must be no insulation whatsoever in the porch roof. It is pretty obvious that there is no insulation in the outside walls.

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That’s not a 3-tab.

The flue pipe crap-show is as close to a smoking-gun as you’ll get.

That roof looks borderline too low-slope for a shingle.


Low slope for shingle? What would be the other choice?

Flat roofing of some type - TPO/PVC/EPDM. Some shingles will go down to a 2:12 with certain underlayment requirements. That’s probably more than 2:12 but still pretty low and more likely to leak.

I’m mainly judging by the interior photo but I suppose that may not be a true vaulted ceiling (as in the interior ceiling slope might not be the actual slope of the roof).

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The pitch looks more like a 3.12 to a 4.12 based on the pic, possibly a 5.12


The water flow from the higher pitched roof to the right may contribute to the problem.

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My money is at the fireplace flue pipe.

You sure? What was the exterior temp today? That scan temp shows 78, and there is a heat wave around most of the country right now

Maybe I’m old-fashioned but I don’t understand what the purpose of an infrared camera is here. You’ve got a crappy roof penetration and a leak below. What benefit is the camera providing?


It felt like around a 4:12 slope over the porch. The main roof was definitely pretty steep, say 6:12 or even 7:12. I thought about the concentrated flow - definitely a concern. But, figuring that most of the flow would be to the inside of the stove chimney, not to the outside (where the problem is). At this point there is no concensus. So, it is probably going to take a roofing contractor to start tearing off shingles until the problem is revealed. Perhaps they could get away with only a partial re-roof.


There could be a plastic vapor barrier on the ceiling, and the leak could be ten feet away from where it is exiting?


Definitely possible.

Do the gutters have a leaf guard or are they just flat out full of crap? If they have leaf guards that are plugged up or if the gutters are full, then even rain water can back up under the shingles, etc…
Also you said California Mountains, that makes me think snow, if the gutters can’t drain away the snow melt, where is the water going to go???

Combine old shingles, which BTW are not 3 tab, a steep roof plane adjacent to the not so steep roof, and clogged gutters then you could have multiple issues and multiple “entry points” for the water. The only thing I can see for sure is a pricy repair bill :dollar::dollar::dollar:

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I would suspect Ice damming in this area has caused water to back up under the shingles.