Originally Posted by GBR in WA
Sorry I gave you the wrong idea in not being specific enough. I should have said- Check to see from the BSC site if plastic (Class 1) is required or just a Class 2, vapor barrier primer paint on the lid from below. In your case the plastic would be extremely hard to do..... after the fact. V.b. vs v.r.; http://www.energysavers.gov/your_hom.../mytopic=11810
Is the frost at the sheathing/gable framing because the fan moisture is trying the exit and because it is colder there, condensing and freezing?
Just cut a new bath fan hole lower down on the gable, just above the insulation. Run ducting up at the fan to get some fall over the rest of run for drainage. Be sure to insulate and v.b. the ducting, air seal all joints (even the individual elbow ones). Another option; http://homes.winnipegfreepress.com/i...article&id=702
Thanks Gary, and yes, it could be that the fan is not venting as well as I had hoped, and the vapor is getting trapped under the peak, condensing, running down and freezing. We don't use the bathroom fan all that often as I take showers in the bathroom downstairs and not this one, but heat would constantly be escaping. I'm thinking cutting in lower is a good plan...
I was thinking, the fan is only about 2 feet from an exterior wall in the bathroom, I'll take a photo of the bathroom/wall and the one in the attic where the pipe comes in... I might be able to run it that way...much shorter distance.
There is frost on the other side of the attic also at the other gable, but its not as bad as the side with the fan venting out.
@mem: As far as the vapor barrier issue, I though I had seen some posts about that in this thread... I must be mistaken.
I'm thinking, looking back, the frost issue has been the poor installation of the ridge vent the entire time :-(
For starters, I'm going to go up there this weekend, check for vapor barrier, and I'm going to remove those pieces of batten insulation that are blocking the baffles out to the soffits. Hopefully that increases the airflow up to the ridge vent and reduces the frost.
If I think about this logically:
The house is about 32 years old. The roof was redone in 2003. Obviously, if this had been an issue the entire time, the roof would be rotten.
1-The insulation amount did not change.
2-The Soffit configuration did not change.
3-The attic hatches have not changed
The only thing that changed was the addition of this ridge vent and the fact they did not seal up the gables when they installed it.
AFTER the frost/moisture was discovered I:
2-Added the TrueVents and blocked off with insulation (now will remove)
3-Sealed up the attic hatches
4-Removed a leaky air exchanger and all the duct work. Sealed all louver holes into attic (4 of them)
5-Sealed the Gables
6-Re-routed the fan Duct from a soffit to the gable.
What do you guys think?
So in the spring, I'm going to hire a roofer to properly cut the ridge to the recommended size and install this type of ridge vent:
and have him install these
I'll then install those continuous soffit vents around the entire house.