"keeena" wrote in message
ps.com...
Hi,
Before I begin, I will note that I searched the NGs for this problem
and found enough answers to get me started. I want to get some more
input based on my specific problem. I just noticed this issue in Nov;
I'm in MA and its easily below freezing @ night.

HOUSE INFO: Attic shingle nails are wet and many of them have droplets
hanging/dripping from them.. House is 1.5 yrs old, colonial. R30 in
attic, kraft-faced, facing living space. Facing is not tacked to
joists, insulation is just stuffed in from the top. Ridge and soffit
vents w/ soffit vent "ducts" (no blockages). I keep the heat fairly
low in the winter (60*). No ice on nails. No rain in the last few
days (and no snow yet). Never had icicles on the outside of the house
last winter and roof seemed to have uniform frost/snow coverage.

I'm pretty sure its a condensation issue. I'm going to look at sealing
up all openings: whole house fan, bathroom fans/ducting and lighting.
I do remove the WHF in the winter and cover the opening w/ 2 sheets of
foam insulation (4-5" thick tot.), but this is probably still leaking
lots of air and hopefully the major culprit.

QUESTIONS: How significant of a problem is this? I don't have any
water spots on my drywalled ceiling. I noticed it due to water drops
on attic-side of the access panel (which is insulated and has a foam
gasket).

Does this stuffed-in kraft-faced fiberglass normally create a
sufficient vapor barrier? Or will I still have issues after
super-insulating the items I mentioned above? I'd rather have taped
6mil vapor barrier across all the joists coupled w/ unfaced batts
(prior to furring strips & drywall). I'm under the impression that VB
should be continuous and right now its far from it.

Lastly, are there any other things to investigate which may help? I'd
rather not redo the ceiling or add more insulation. I may want to add
gable vents due to poor exhaust for the WHF (ridge/soffit doesn't cut
it...another story). Would add'l vents help this condensation problem
by naturally venting more attic air?

Big thanks,
-K

The two most common reason for what you describe are water in a crawl space
or a whole house humidifier set too high on the humidistat. I've been in
attics in the winter that you could use a raincoat and umbrella. If the RH
(relative humidity) is very high in the house it will migrate to the attic,
where it will condense on the cold decking of the roof.

Sealing up the attic won't help because the circulation of cooler, dryer
outdoor air will lower the RH of air in the attic and would help with your
problem not make it worse. Cooler air can not hold as much vapor as warmer
air, so cooler air is normally dryer air.