Condensation in eaves with non-vented soffit

[PILOON]

I had a client with close to same situation.
He wanted me to re do his roofing due to leakage but as I pointed out his shingles were still good and his problem lay elsewhere.
Eaves totally filled with insulation and a cathedral ceiling also packed full of insulation.
My solutions that worked as jury rigged as it was.

I wrapped 1 x 3 furring strip ends with a plastic bag and slipped the strips between the roof deck and insulation and when inserted used a pipe wrench to rotate the strip. This created a tunnel for the warm air to exit up top near the roof peak. (sort of like a mini attic)
(The plastic bag was needed to prevent the insulation from bunching up when inserting the furring strips.)
I next created vents near the roof peak to allow heat to exit.
Naturally we did have to pry loose some sofit in order to insert out wrapped furring strips but that was fairly easy to re attach.
He was able to get another 6-7 years with same roofing until he did a very major renovation of the entire house.

For venting a product made by MAXIMUM is well rated.
Like a small 4 sided box with louvers on 4 sides c/w flashing and adjustable for different pitches.
Either way, you want passages for complete attic air circulation.

The cold sides of knee walls need to be treated just like an attic as in effect they are actually part of the ceiling.

 

[tlj87]

I got int the knee wall on the opposite end (east/right) today. All wood was dry. It appeared as though the insulation either never went down to the soffit or was trimmed back at some point after construction.

 

[dave1949]

Is the wet side the dormer side? Dormers are notorious for leaking if the roof isn't done correctly.

Is the bath or kitchen under the wet side or dry side, or neither?

 

[tlj87]

The bathroom is in fact under the damp area. The damp wood was on the front and back of the cabin although the bathroom is only on the front portion. The ~3' space above the ceiling of the bathroom extends to the room behind it. (Both rooms are on slab vs. the rest of the living space which is above a crawl space). I suppose moisture could have migrated through that ~3' space to affect both the front and back. The bathroom does have an exhaust fan that is vented through the west end wall of the building. Remember that in these two places the fiberglass insulation extended down to the wall below unlike the east end where it did not (and the wood wasn't damp). Here is a very rough layout sketch from the front:

 

[dave1949]

Well, best thing to do now, with the damp insulation out, is to monitor the situation and see what happens I think.

My best guess is it is either moisture from the bathroom migrating through the 3' ceiling area, or that side of the dormer leaks. Moisture will migrate through painted wallboard, wood, etc. Most bathroom fans eventually clear shower steam but are generally on the wimpy side in terms of cfm's.

You could lay plastic down on the 3' knee wall floor for a few days, check it for condensation on the underside.

 

[tlj87]

Ok, thanks for your suggestions. I will do that and see what happens. The contractor that did the roof in '08 is coming out today or tomorrow to take a look and see what route to go down. I'll try to update with my findings.

 

[dave1949]

Sounds like a plan. Good luck!

Any moisture that makes it into that unvented soffit and eave really has no good way to leave. It probably accumulates over time. The fiberglass insulation soaks it up and holds it like a sponge.

 

[tlj87]

Contractor came out yesterday. He suggested trying to seal off air leaks and the eaves from the living space with foam board, caulk, etc. I neglected to ask, but what kind of foam board should I get? I would think the foil faced ISO as it that serves as the vapor barrier? I think this is what I am trying to achieve with the eaves, although at this time I can't run the rigid foam all the way up the walls inside : http://www.finehomebuilding.com/CMS/uploadedimages/Fine_Homebuilding/Articles/221/021221071-1.jpg


I also am getting quote on drywalling the bathroom. Right now it is all plywood paneling and I suspect moisture is getting through the seams.

 

[PILOON]

If you drywall the Bath Rm be sure to use the blue drywall board that is made just for that.(might also be green).
Best still is a cement board but that's pricy and generally only used behind shower and bath tiles.

 

[tlj87]

Well here we are in the spring. We decided to rip out all of the paneling and fiberglass insulation and have spray foam and drywall installed to address our issue. After monitoring and thinking all winter, I decided the issue wasn't a moisture leak but just inadequate insulation. Most all of the roof deck was frosty on the underside at times because the insulation was way weak to keep the hot air in and the cold air out, so the dew point was reached. Lots of ice dams on the shady side of the roof. So after quite a bit of research, we went with open cell foam from the soffit to the peak, including the gable end walls, dormers etc. essentially everything above the first floor. We will also be replacing all windows with Andersen 400 series. And then some work in the bathroom including foam on the outside walls, drywall, tile floor with heat below it. Definitely some $, but it's time.