Was this staining outside indicative of a problem inside?
Looking up these foundation stains were directly under a third-floor, bathroom window. The two bathrooms abutted and shared a single drain stack which ended in the basement.
The siding was new, but these stains were old and had two colors, indicating they happened more than once.
Seeing these stains I suspected a plumbing problem indoors.
Looking inside I saw what appeared to be previous leaking, and an unprofessional repair. So I ran the water in both bathrooms at the same time, and for a while.
The sill plate (the board on top of the foundation) was black and rotted.
The floor joists nearby were black and rotted where they rested on the sill plate.
The rim joist (the board covering the outside opening where the floor joists end) was black and rotted. That is where the staining in the first photo was manifesting.
And, after running the water, droplets could be seen in the white poly foam.
Someone apparently thought that poly foam would "seal" up the leaking. It did not. Open-cell poly foam, like you see here, is not waterproof and should not be used to seal leaks.
Further, that poly foam makes it exceptionally more difficult to get to and analyze the source(s) of the problem(s).
In short, this was a mess. It will require the investigation of a plumber and a structural engineer.
My recommendation: looking outside often gives clues as to circumstances inside! Have a look. I typically arrive early to walk around a house, first looking at the grounds - grading and vegetation. Then again looking at the lower half of the house. And then again (!) looking at the upper half of the house. By that time, when I walk around the house with the buyer I have informed myself and can talk about things and suggest a plan of action for when we get indoors. When I see clues outdoors I am looking indoors to see if they lead anywhere. Sometimes they do!
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560