Well, I've been slowly insulating my attic space (R30fiberglass unfaced on top of existing R19 kraft faced which is over some felt paper filled with vermiculate or similar) over the past few weeks. Noticed today as I went up for another round of installation that there's mold on the sheathing surface and a large wet area on the sheathing about 16'wide by 2-3' high. Lots of moisture on the nail heads as well. this is all on the north side of the house. South side surface is perfectly fine. It's been fairly dry even though it was raining for the first time in a week today.
I had a couple other threads where Dana had helped me with some ideas on insulating near the soffits. This is a brick house with no soffits. The only venting comes from the gable ends. I was going to add the rigid foam and seal around at those locations but it's impossible to reach and do a thorough job. Now I'm just using baffles (not sure why at this point) and sending insulation (fiberglass) underneath along the whole ceiling.
I'm really confused as what to do now. I'm 90% certain this is a moisture issue related to water vapor and not a roof leak because the area is so large. Not sure why its just affecting an area about 1/3 of the way up.(roof is 3 tab installed in 98) Originally insulation was shoved all the way to the ends of the roof line with no baffles. As I pulled the insulation back it looked like the sheathing was dry below but immediately above it was when the moisture would begin. It actually feels soaked to the touch and the knots (tongue and groove pine) are really wet making me believe its definitely an issue of condensation. I'm going to keep insulating and installing baffles. My hope is there is some air leakage at the ends of the eaves where some air may roll up into the attic cavity.
Part of my concern is due to the construction (brick, air cavity, stud wall, plaster) in a really wet ground (high ground water table) that the cavity between the brick and stud wall is sending moist vapor up into the attic. Not sure if this is the case as I'm not certain how the construction is done in a case like this.
If anyone has any idea what might be going on please help. I've also gone through the attic and sealed off all the locations I can find of wires or vent stacks/light fixtures coming through the living area. Will eventually insulate the basement with rigid foam and spray foam in the area above the bottom plate hoping this will help reduce the migration of heat loss up to the attics space. Just not sure if humidity is coming from brick or somewhere else.
I've been in this house for 4 years now. I've noticed on previous observations some water staining in this same area and assumed it was ice damn related but not too certain now. I'm guessing this has been going on for some time but more worried this is more as a result of my recent activity in pulling the insulation blockage away from the roof.
Hope you can help. Not liking the way it is up there right now.