Hi, about 2 years ago I had an addition on my house, all new framing and insulation. At the end of last winter I noticed a wet spot on the bathroom ceiling. I called a roofer who did not notice any leaks in the roof it noted that there was a lot of moisture in the attic. As recommend an attic fan with temperature and humidity sensors. The humidity has been maintained between 50 and 70 percent. We had a rapid cool down the other night and the spot returned, but the attic does not feel damp or show evidence of a roof leak, however that section of the roof is not accessable. I removed some of the drywall and there is a nail plate right where the ceiling/wall is wet. The insulation is also wet there. There is a pvc vent pipe that goes through that wall bay. I am thinking that the plate being on an exterior wall and extends slightly above the wall it getting cold and the interior warmed air is causing condensation. It just seemed like it was too much water damage for that. Anyone have thoughts or experienced something like this? Thanks

I appreciate it!! Thank you!!

You need to trim your way out of this somehow.

There may or may not be blocking, but to get to the basement, you will have to go through what I think is called a sill plate. If you can locate exactly where in the basement would be below your wall opening, you might be able to drill up through the sill plate and then push a stiff wire up inside the wall. I did that in my 1895 house to run some wires, but there was no insulation in that wall. Another possibility would be to temporarily remove the baseboard and drill a hole in the sill plate from above. Of course, a professional electrician would know all the tricks for doing this.