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Bit of a head sctratcher.


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A previous client contacted me about a roof leak that was occurring at their home. Has been about 18 months since the inspection. The home was built in 2007, 20yr three-tab shingle roof. What has me scratching my head, is where the leak(s) is showing. Not at a seam. Not at a roof can. Right in the middle of the sheathing. The shingles appear to have been installed correctly. All of the key's were over the shingle below.

Took a while for this to show. My first instinct is a nail head? Any other suggestions?

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I have seen them before and sometimes its impossible to figure out. The first thing I look for is an exposed nail or a hole in a shingle. I see many like that where scaffold brackets were nailed through shingles, but they are always close to edges.

Sometimes it can be water traveling down from above or from a nearby valley, but then usually would enter at a seam. Could have entered through a nail hole in the sheathing that it not in the roofing.

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I had something similar where there was wind damage to a couple of other shingles and a wet spot like that several feet away. I was able to lift a few shingles, so came up with this - wind lifted some shingles and blew rain in under.

The curse of untreated OSB is that it absorbs that water rather than shedding it.

It is a good bet there is no roofing paper under those shingles. 3 or 4 rolls of roofing paper underlay might have saved that roof for a few more years.

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It is a good bet there is no roofing paper under those shingles. 3 or 4 rolls of roofing paper underlay might have saved that roof for a few more years.

Probably. No underlayment, at least at those areas. I assume you lifted some shingles at the eave when you did the inspection and saw roofing paper. One layer of underlayment should stop leaks that severe I would think.

Did you rule out high indoor humidity bleeding into a cold attic?

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I also wonder if it's actually humidity and not a roof leak. Any chance there are can lights buried just under that insulation... although it's hard to want to crawl over there to see. How did they notice the leak? How much water came into the house?

Did you lift any of the tabs and see what the nailing looks like? There wouldn't be any toe-board nails on a roof like that.

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I'm going with missing underlayment or like Mike said about it being installed wrong in that area. Look at all of the other dark spot in the same area, it looks like it has done it before.

On a properly installed roof, the underlayment never gets wet save for the rare wind event that drives water uphill for 5 inches.

There's a nail between tabs, a nail worked up through the cover or two seams are aligned.

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The humidity levels were normal in the home. No cans. No forced air but wall heaters. I did look at the gutter edge and did see roofing paper.

The water appears to be literally pouring in the home. The main section, is now covered with tarp which did stop the water from entering the home. I couldn't find any damaged sheetrock.

The other strange thing, is that it's only happening at the front plane of the roof, nothing at the back.

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The humidity levels were normal in the home. No cans. No forced air but wall heaters. I did look at the gutter edge and did see roofing paper.

The water appears to be literally pouring in the home. The main section, is now covered with tarp which did stop the water from entering the home. I couldn't find any damaged sheetrock.

The other strange thing, is that it's only happening at the front plane of the roof, nothing at the back.

Why is that strange? There's a roof leak.

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Chad,

Just strange that the leak or leaks in this case are only showing at the front.

Things work until they don't. A roof doesn't start leaking all over all at once.

That roof is only 8 years old. No visible damage. Something is not right with the installation.

Robert, a strip of paper at the eaves is pretty standard, but then they will lay the rest of the shingles without underlayment. Even so, the roof doesn't usually fail that way so soon.

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Robert - It's due to such conditions that I include the following in my report; "Please be aware that even roofs that appear to be satisfactory can still leak. So while the

inspection may not find a concern there can still be a bit of an unknown over

the roof's ability to shed water." This helps set the client's expectation of my inspections.

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Is it just in that one area of the front plane of the roof? I see a gable end wall in your pic..

If so, is it possible that the rake edge shingles aren't installed properly, and that the water is working its way in from there? If that rake / gable truss sits just a little higher, water will run in and downwards diagonally. Then, water will travel down atop the felt paper until it finds a weak point to drip through.

Make sense?

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