Water underneath attic vapour barrer. Need help

I noticed paint bubbling in my kitchen ceiling. I went into the attic andfound alotof water underneath the tar paper vapour barrier as well as on top of the tar paper, which must have been soaked trough. The insulation is opnlywet where it meets the vapourbarrier. What the hell is going on here. I've about 50 sq feet of dammage plaster celing.
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Do you have a ceiling exhaust fan ? If so , is it venting into your attic or out the roof or eave vent ? If there is a fan exhausting or even leaking into the attic , your pumping warm humid air into a cold attic causing moisture . That is a no no ! If this isn't the problem , you either have a roof leak ( possibly ice damming ) or your house is so tight you have a moisture problem . Humidifiers can cause this if the house can't breathe . Just a couple sugestions to start investigating . Hope it helps .
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On Mar 16, 5:31 pm, snipped-for-privacy@sbcglobal.net wrote:

I think I hit the wrong post button. Anyway, what I was saying, is that the water is under the barrier against the celing material. I did have a lot of ice on the roof, so much that it had forced its way under the shingles and made the wood panels wet. This however dried up within two days of me clearing the ice. I'm so confused because the insulation is not wet. It's only wet way down deep where it meets the vapour barrier. I do have a vented microwave that goes out the roof through the attic, but this duct is insualted.
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Jetmech wrote:

bottom of the layer, as water drains quickly and the top of it would not feel wet. Sounds like you had an ice dam that backed up and dripped on the insulation. It would flow across the vapor barrier and collect, seeping slowly through seams and/or nail holes. Water could collect in the bottom of the space for some time before leaking through the barrier, and that would allow the upper portion of the insulation to feel dry. That is only my logic :o)
I had a similar backup, just from gutters being full of leaves (Florida, no ice) and got a smaller wet spot on a ceiling.
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Do you have a bathroom exhaust fan - is it anywhere near the area ? Are you sure the the piping from a fan ( especially if it's flexible ) is not leaking or not connected at the fan properly , thus allowing humid air to escape ? There could be a spot in the pipng that moisture is puddling at and leaking ? Was the snow or ice sitting above where it vents out the roof ? If so , this could cause the warm air to melt any ice or snow above and arround the roof vent , and it is melting back down in thru the vent into the house . Is your house humidified ?
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My understanding is that tar paper is a moisture barrier, not a vapor barrier - that is, it allows vapor to pass through it. So, the vapor in your house passes through it, then condenses in the insulation. It is possible a vapor barrier paint could help. Otherwise, install a proper vapor barrier in the attic under the insulation, or install insulation with a built in vapor barrier.
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Theres no venting from anything in the attic. The exhaust from thr Microwave is 6 inch galvanized insulated pipe. It's blowing into a lot of snow and has melted a large patch. The damage area in the attic is about 50 sq ft. It is also above the portion of the kitchen where all the cooking is done. i.e the stove is there, kettles, etc. I do have a humidified house that is automatically controlled. At -10 C I think I'm around 29% relatice humidity. Could this be as was mentioned, moisture going through the tar paper? Would 6 mil plastic be better? Does that much moisture actually travel through the celing? Right now I'v removed the damaged insulation in the hopes of the celing drying out.
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I'm no expert here . I have experienced some problems like you . No matter what , whether you have a leak , or a moisture problem , replacing the barrier is half the battle . You still need to address where the moisture is coming from , and how you are going to remove it from your house . There seems to be a lot to cause that damage and it needs to be removed from your house .
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Or Stopped !!!
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On Mar 16, 6:18 pm, snipped-for-privacy@sbcglobal.net wrote:

Thanks for all fo your input everyone. As I said earlier. There was quit a lot of leakage through the shingles over the whole damaged area. The wood wood roof panels were wet to the touch. If thats true what was said about fibreglass insulation allowing water to penetrate quickly, then all this may just make sense. I'm assuming the tar paper will let the water through it eventually? I have loose fill blown in over bats by the way
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Jetmech wrote:

:o), but the idea of water draining quickly through the insulation so that the top of the layer feels dry would not seem to apply to cellulose.........the vapor barrier is between the ceiling and the insulation, right? It doesn't make sense, to me, that moisture from the indoor space would move through the ceiling, through the v.b., and collect above the v.b.
Got soffits or open rafters? Any plumbing in the attic space? If the insulation is real wet, and the plaster is wet, I would be concerned about the added weight causing it to fall down. Real plaster? Any sags?
Another thought is whether wind driven rain might have added water in addition to whatever came from the ice dam. Had bad wind storms? Got plenty of ventillation and ridge vents? It would be worthwhile to have a couple of roofers look at it, get bids for any needed repairs and/or vents.
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Got plenty of ventillation

This is exactly what I was leaning toward . It could be damming . It could be a moisture problem . It could be a combo of things . The house could simply not be breathing !
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On Mar 16, 7:47 pm, snipped-for-privacy@sbcglobal.net wrote:

We have had real bad winds this winter blowing right at the back of the house. Where my problem is. But the problem is still somewhat localized and the penetration is at least 10 feet away from the soffits. The vapour barrier is between the ceiling and the insulation. Will the tar paper let water penetrate through it, so that it comes in contact with the giprock? If so then this is most likely the cause. As dfar as solving the ice damn, im re-doing the eaves this summer and adding the heated wire for the winter. I shoveled some of the snow off the roof gently I may add. The damaged are is under the part of the roof that would be 1/3 of the way from the wall (side split) and 10 feet from the eaves so past the ice guard. About mid way between the eaves and the peak. The rood is 5 years old, well shingles I mean. And black paper was applied to the whole roof and the bottom 3 feet have the rubber ice guard as well as a drip edge.
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This has to be water from above. I just read an artical saying that if you have at least two coats of oil based paint on the cealing, then that alone is a vapour barrier, and one in the attic is not really required. This was a question from an individual who wanted to insulate an 80 year old home's attic, and was told to not even bother if that plaster celaing is coated in oil. For that matter I can guarantee my 42 year old cealing is covered in oil as well. theres no way the water below my tar paper came up from the kitchen, it would have to be from above. oes this make sense to any of you?
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clipped

through a coat of paint. Acryllic paint allegedly breathes a tad more than oil, but it is still waterproofing. Someone said something about a microwave vent melting snow - OP or someone else? Vent penetration or flashing can leak, so those should be looked at as possibilities. My daughter recently had a leak in an area of repeat problems from a bad remodel.ing feature. She is happy to have a roof over her head and if it leaks a little bit, well, life could be a whole lot worse :o) We talked about roof leaks and got to the matter of ice dams. She called me back the next day to tell me what happened when she cleaned her gutters :o)
If I remember the formula, there should be one square foot of ridge vent for each 300 square feet of attic FLOOR space. Sounds like your problem might be too high, but I don't know how high ice damming can leak. I've seen small leaks follow a rafter or brace and fall far from where the water enters. Good luck!
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While doing some more reading, Im thinking that the paper in my attic may indeed be Kraft paper. It's very thin, black on the side facing up.
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According to http://www.bpa.gov/energy/n/energy_Tips/weatherization/vaporbarrier.cfm that would work.
It doesn't take much moisture getting through to add up over time, as very little evaporates in the cold temps.
Obviously, leakage has to be dealt with separately.
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 Does that much moisture actually travel through the

The best way to explain it is that you have moist - warm - rising air , penetrating the ceiling . It reaches the colder attic and is condensating under the barrier . It may actually frost up under there until it warms up . When it thaws , then the problem starts . Just like a glass off ice water . Cold water inside the glass , warm on the outside . Then the glass sweats and you have moisture on the outside . More so if it is humid out . If this indeed is your problem , the humidity in your kitchen as you cook could cause these problems . If so , you need to rid your house of extra humidity possibly caused by cooking or showers .
But then there is the damming problem ! The heat loss from your house helps cause this . Just make sure you find the true culprit .
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Jetmech - Just a heads up . Removing snow from your roof is ok . Removing the ice is another question . You may actually damage your roof and shingles more if you physically try to remove it . You did claim you removed it correct ? Frozen shingles are hard and brittle . They crack easily . I'm not sure if you are saying you did this . But doing so is asking for more problems . Good Luck !!!
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THAT's why you don't use a vapor barrier in attic insulation....
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