Molly,

We have run into bituminous stuff (since you're a female person, I'll resist
the urge to call it "shit") applied to the interior faces of exterior walls
as a waterproofing membrane, so that the wind-driven rain gets stuck
"outside" instead of being  allowed to pass all the way through the wall.
The prob is that there are voids in the bituminous material and the water
makes it through anyway.  We've seen it applied to the inner face of (really
shitty) CMU backup walls from the 50's-60's, which themselves are full of
voids (since they're backup walls, after all).  I presume in your
recently-seen theaters, you saw this stuff on terra cotta.

Ralph