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2023-11: Warosu is now out of extended maintenance.

/diy/ - Do It Yourself

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1586079 No.1586079 [Reply] [Original]

I bought a house with an attic that had R-19 insulation on the floor (cold attic) and I went and installed more insulation (R-30) over top of that about 5 years ago to try to save some on heating. It did cut down on oil usage, but long story short, I haven't been up there since I installed it 5 years ago, and this past winter I went up and the underside of the roof decking on the north side of the house only was sopping wet, presumably from inadequate ventilation and high humidity, which is probably from the poor vapor barrier between the living space and attic. I think the 70 degree house air is making its way into the attic, through or around the insulation and then the water is condensing out on the cold underside of the north facing roof. I'm hoping I can solve this by installing soffit vents (there were none) and using the existing gable wall vents, maybe with the addition of a fan to pull humid air out of the attic to keep the decking dry. My question is, if I do install a fan, what should the temperature and humidity ON setpoints be? I have the soffit vents in and will continue to check for moisture, but I'd be more comfortable venting the air at a humidity level below the point where my decking gets saturated. Any recommendations?

>> No.1586199

No need for power venting in winter. Just add the soffit vents.

>> No.1586637
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1586637

>>1586199
thanks, you think soffit vents + gable vents is sufficient? Any need for a ridge vent?

>> No.1587116

Can't say without knowing your climate.

>> No.1587117

>>1586079
Attics should be ambient temp, my house has soffit, ridge vent, and a few square vents. Can’t have enough ventilation.

>> No.1587124

>>1586637

stop posting that asian with orange palms pls.

thx.

ok bye

>> No.1587157

>>1587116
Why does the climate matter? I'm not disagreeing, because a lot of stuff online said 'depends on the climate'. In my retard brain it seems like there should be a number for humidity, above which wood decking gets moist, and below which it doesn't have problems?

>> No.1587157,1 [INTERNAL] 

Have you tried that on composite decking? I am thinking to do that too.