Originally Posted by
Michael Thomas
Grade is a few inches below the window in the first picture.
Well ... most of it is below the window, and the height of it above the grade level could be saturation and soaking into the wall for the past 100 years ...
That black mottling did have sort of petroleum-based product sheen to it, though.
Could there have been an oil line(s) through the wall which was parged over?
If so, oil could have leaked outside that wall.
On those old homes, what was used as "waterproofing" on those walls? A petroleum based mixture (think 90 weight gear oil) mopped onto those walls? (I have no idea what was used 'back then', however, I am sure they used what was handy and locally available, maybe creosote type stuff?