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We have just replaced our 30+ year old shake roof with a metal roof this summer. Due to the stormy conditions of our West Coast Canadian location, shakes were not a viable option. We sit on a cliff that is quite exposed to South-eastern winds , sometimes up to 80 km many times a month. We had previously experience leaking due to rain being pushed backwards up the roof by the winds.
After having the roof replaced I increased the soffit vents by 4 times since the shake roof “breathed” and the new metal roof with roofing felt underneath, did not. I now have about 4 sqft of soffit vents for 1200 sqft of ceiling area. The Ridge cap on the roof has gaskets along it to prevent water from backing up into the peak, but I was told these “Breathe”.
My problem is a familiar one… I am still getting condensation on the underside of the roof in our attic, though, it is only on the north side.
We have pink insulation in the attic… I believe it is about R20…
I am about to add a large gable vent at the peak of one of the gable ends.. I can’t on the other gable end since it faces the brunt of our winter storms…. and the high winds…
Will this be enough to reduce our moisture problem? What else can I do… I do not want to put vents in the roof itself… due to our high rains and trying to maintain a leak-proof membrane.
Brian Pearson
Replies
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the moisture probably is condensation which is caused by a leakage of warm, moist air coming from inside the house. i think you will stop the moisture when you stop the air leak from below. i also don't believe the 4 sq ft. are enough nor maybe not uniformly placed. best of luck to ya
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*Brian, I don't have an answer for your problem but am familiar with the enviromental conditons stated. I've been wondering if the outside air is so laden with moisture that it is pointless to vent it through the attic to dry out anything. In a year or 2 I'll have a more developed opinion about this.Joe another left-coaster.
*Sometimes, venting can do more harm than good.If night is cool and morning in humid, letting the water laden air in to the attic space will cause condensation.I would suggest a plastic vapor barrier in the underside of rafters. This might keep moisture from getting to the metal roofing and might not work if the plastic gets cold too.your attic vents can get automatic shutters or a ventilation fan that is controlled by a thermostat and/or humidistat.
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We have just replaced our 30+ year old shake roof with a metal roof this summer. Due to the stormy conditions of our West Coast Canadian location, shakes were not a viable option. We sit on a cliff that is quite exposed to South-eastern winds , sometimes up to 80 km many times a month. We had previously experience leaking due to rain being pushed backwards up the roof by the winds.
After having the roof replaced I increased the soffit vents by 4 times since the shake roof "breathed" and the new metal roof with roofing felt underneath, did not. I now have about 4 sqft of soffit vents for 1200 sqft of ceiling area. The Ridge cap on the roof has gaskets along it to prevent water from backing up into the peak, but I was told these "Breathe".
My problem is a familiar one... I am still getting condensation on the underside of the roof in our attic, though, it is only on the north side.
We have pink insulation in the attic... I believe it is about R20...
I am about to add a large gable vent at the peak of one of the gable ends.. I can't on the other gable end since it faces the brunt of our winter storms.... and the high winds...
Will this be enough to reduce our moisture problem? What else can I do... I do not want to put vents in the roof itself... due to our high rains and trying to maintain a leak-proof membrane.
Brian Pearson