Hello. I just peaked into my attic and I noticed some drips here and there. I live in Wisconsin and we currently have a quarter-inch of snow on the hip-style asphalt shingle roof.
What is funny is that I did some significant work up there during the summer and during heavy rain storms, there were no leaks.
Please advise. How do I repair these? It seems impossible to do any kind of roof work when the slooped roof is covered with snow!
Help!
live in Wisconsin and we currently
Could it be condensation? It's not uncommon for moisture in the attic to condense on the cold roof surfaces, form ice, and then melt again when the attic gets a bit warmer.
Go up there on a very cold day and look for frost formation. And if you have frost it may indicate excessive humidity in attic.
Jim
live in Wisconsin and we currently
Yes, I think you are right. In the summer, I replaced the old attic fan with one of those "all-season" ones that have the humidity sensor. The humidity is quite high up there as I activated the sensor at 65% and she is running. The problem is that the outside humidity is 70% so I'm not sure if it will ever turn off.
There is no frost present. How do you prevent condensation when the outside air is humid, the attic air is humid, but the surfaces are very cold.
Block the vents, and run a dehumidifier. When it gets cold enough so that icing on the roof looks like a realistic hazard, shut it off and unblock the vents.
in Wisconsin and we currently
If you don't see the actual dripping, and going by marks on the insulation, it's probly condensation off the roofing nails.
Check it further....
later,
tom @
Humidity is relative to the temprature. If your attic is warmer than it is outside then the moisture will not condense. Also the motion of the air helps also. This is why there is no fog if there is a decent breeze.
At 70% humidity dew will not form on the ground, so it should not form in your attic.
Roger Shoaf wrote: ...
Not necessarily so...dew may well form on the ground just not in the air as fog and may OP may well condense moisture out in the attic on cold surfaces even if the bulk air temperature is above ambient. As some other responder noted, protruding nails, etc., are prime candidates...
(Same phenomenon as the "sweating" of a water glass...
...
Just not so...if air movement is enough, yes, you may avoid it...but it's not so, and it is for there to be cold surfaces that are below the ambient air...
There's not enough data for to tell whether that is or is not the case in OP's case, but it is certainly a possiblilty to look for...
At 70% humidity the only way to get the water to come out of the air is to lower the tempriture of the air to the dew point. If the air is in motion, it will not be incontact with the colder surface long enough to cool and therefore condense.
In an attic you have problems if the air in the attic gets colder and the humidity rises. If the warm moist air goes out the ridge vent and it is displaced my colder air coming in from the soffet vents the air will warm a little and the humitity will drop. If however the attic is full of air at
70% humidity and has nowhere to go and the tempriture drops, then the humidity will rise to the point where it will condense on to the cold parts of the roof.Rather than the ice water on a warm day consider foggy windows in your car, and a disfunctional defroster. If you roll down the window and drop the tempriture on the inside of the glass to equal the outside, the fog goes away, if you try and just wipe the window the fog comes right back. If your heater finally kicks in, and you can raise the tempriture of the air in the car enough the air can hold enough moisture and your window stays fog free.
With your example of the cold glass on a warm day if your glass was in a sufficient air flow the air tempriture would not drop fast enough to reach the condensation point and therefore the outside of the glass would stay dry.
I would like to suggest that if the roof (due to radiant loss of heat at night) gets cool enough to form dew or frost on the outside, it is cool enough to form dew or frost on the inside if the humidity levels are similar. SJF
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