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90%-er
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Discussion Starter · #1 ·
Was called out to a customer today who had some fresh water staining in a couple of upstairs rooms, on outside of the house.

I headed up into the attic/crawlspace and discovered all of the OSB sheathing on the inside of the peak of the roof was wet. It was shiny and damp to the touch.

My suspicion is that since the entire wall is pretty universally wet, that we aren't dealing with a leak here per se, but somehow vapor is penetrating that wall then condensing and dripping down. This is outside of my area of expertise now and I told him as much, but I promised to ask the forum to help point him in the right direction.

If it helps, we are in a very cold climate here. He says it seems like the water coming down is worse in the evening.

Anyway, sorry about the quality of the pics. Hopefully they contribute something. This is me standing on the trusses and facing that outer wall.

Vapor barrier issue? Time to tear down siding?
 

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Did you inspect the outside? Any rotted trim? Is the underside of the roof also wet? Is there snow on the roof? Answers help narrow it down.
 

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90%-er
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Discussion Starter · #4 ·
Did you inspect the outside? Any rotted trim? Is the underside of the roof also wet? Is there snow on the roof? Answers help narrow it down.
The peak is a good 35 feet up, so I can't say 100% on the trim. But these houses are all relatively new and the trim looks good at least from ground level. It just doesn't seem like a leak because there are no obvious water marks on the sheathing; it's just simply wet everywhere.

And it's wet only on that wall, as far as walls go. If it were improper venting of a kitchen or bath, wouldn't we see moisture all over the place and not just isolated to one wall?

There is no snow on the roof right now; but there is no snow on any roof in the neighborhood (almost no snow, anyway. There is still some in the random valley here and there).
 

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90%-er
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Discussion Starter · #5 ·
How much intake vents and breather vents on the roof??
Whew. Got me. Good question. This subdivision is new enough to be still under construction. There are at least a hundred homes in there. It seems unlikely that they missed the mark on vents, but then again I know very little about roofing.

Furthermore, this is a new problem for these folks. They've been there a couple years and this is a recent problem.

It's confounding but I would love to offer them at least a direction to head in.
 

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I would make sure that the bath and kitchen venting is to the outside through the roof and not the soffit. If there are no leaks from the outside it has to be warm are condensing on the sheeting.Any gas appliances venting through that area. This problem could be from day one and only now made its way through the insulation to show water stains. Have a real good look with lots of light.
 

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And it's wet only on that wall, as far as walls go. If it were improper venting of a kitchen or bath, wouldn't we see moisture all over the place and not just isolated to one wall?

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Is it the North wall? Condensation on cooler side, The other side may have just dried out already
 

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Sluggin away
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Call a local inspector or restoration contractor that has a FLIR camera. This could help pinpoint any intrusion points.

I see this quite often and normally its Ice Damming or insulation covering soffit vents.
 

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Head Grunt
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Any kind of overhand to help prevent water intrusion? Snow melt getting past the shingles/felt and behind the drip edge? Ridge vented? May not hurt to install a small gable vent to help air movement through the attic.
 

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Everyone has mentioned to check the home venting, especially the moisture related venting, bath fans, kitchen fans, (and your furnace stack also.) Check/trace each one.

I often find a bath fan just terminated in the attic, maybe hidden/forgotten under insulation. That vent should be run/terminated within 6" of a roof vent (gable or ridge...not a soffit vent).

For some reason, those vents seem to get run up to the attic, and then someone forgets to extend them to a roof vent... and this might explain why the other homes in the division have not noticed/had a problem.
 

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We did a roof a few years ago and noticed the plywood decking was all wet and separated. Come to find out that someone installed a bath fan, but never installed the vent kit through the roof. The bath fan was still buried in the insulation and tape over the outlet for the vent pipe.
The homeowners were very surprised at how well that fan worked after we installed the vent kit.

This could be the problem here. The wall is closer and colder than the roof sheathing so that is where the vapor goes.
 

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Come to find out that someone installed a bath fan, but never installed the vent kit...and tape over the outlet.
I know of a condo development that has about 600 units like that, where there's a bathroom fan, but it's capped off. Light works and fan whirrs though. :laughing: Oh, make that 1200 as each unit had 2 bathrooms.
 

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The Dude
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over that wall? I've seen a lot of those leak at the flashings or windows, roll down the felt, and down the wall. I've also seen leaks at the eave that rolled across the soffit, and down the wall.

Ice damming, debris on roof ... does it only happen when it rains? Ventilation issue, bath fan, etc. I wouldn't tear off siding yet.

I've never heard of a vapor barrier in attic space btw.
 
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