Quote Originally Posted by Rumline View Post
Thanks for the responses. There is a bathroom on that wall, about 10 feet left of the top photo and on the 2nd floor. The pictured part of my house faces southeast and is near the east-pointing corner. The water heater is in the center of the house and so is the sewer line, so that's why I thought there were no pipes going through that area. I guess it could be leaking in/under the bathroom and traveling a ways before coming out.

But judging by the color (and lack of putrid smell) my ignorant mind is inclined to think that Irving is on the right track regarding the tar. The 2nd story overhangs that part of the first floor by about two feet, so the horizontal section you see in the first photo is under the floor of the 2nd story. Can you get an ice dam underneath something like that? Other than blown rain/snow that area "should" stay relatively dry.

There aren't normal sources of humidity behind that wall, it's straddling the kitchen pantry and the dining room. Probably a leak somewhere but could be a siding issue. Our siding is getting near the end of its useful life.

Anybody have recommendations for a siding company in the Springs? I'm thinking I should start there and if they discover a plumbing problem try to call one of those 24-hour plumbers to fix it quick.
I would be chasing moisture to that bathroom.