In the case of the former Walter Mansion in Joisey City, spec-built in 1887
in the middle of a row of 32 houses, 14' and 16' wide, the original roof was
1" thick planking over wood joists, with soldered and painted flat-seam sheet
metal (probably terne-plate). After that, 100 years worth of bituminous
(tarry) muck.  I presume that mine was typical of most brownstone roofs.

I also found original terne plate on the pitched-roofed house I worked on in
Phoenix (1895) and in low-slope sections of our local Town Hall (1892). BTW,
Fat Tony's house, like the current Walter Manse, has slate on its
steep-roofed sections; his is the original Penna; mine was Penna and has been
replaced w/ more durable Vermont.

Anyway, back to Jersey City: Einstein here decided he couldn't possibly put
another layer of bituminous muck (it would've been more than 3, you know, and
3's the limit, even if you're not doing the work under a bldg permit, and we
wouldn't dream of doing anything that wasn't per code, would we?), so he had
the contractor rip it off down to the deck, and put on a nice new layer of
bituminous muck the right way.  Pretty smart, huh?

Well, the only problem was that Einstein had effectively lowered the level of
his roof in relation to the adjoining roofs, creating (theoretically at
least) a pond the size of his entire house, onto which all his neighbors'
roofs would (theoretically) drain.  Whereas if he'd been smart, he would've
saved the labor to rip off the old stuff, making his roof higher than the
ones on each side, and letting it drain onto their roofs.  But, no.......

I don't remember that it actually ever proved to be a problem, but I was
struck (yet again) by how stupid one--this one in particular -- can be in
trying to do the right thing.  Thanks for reminding me.  Maybe you'd like to
put in a call to Mrs. Ralph and remind her, too, even though the JC roof
predated her administration.

Ralph