I found the Balto roof framing method (as described by our distinguished
colleague) a bit bizarre, too, in terms of seemingly uneconomical use of
members, but maybe their row houses are wider than ours.

For a good roof today, we use coal tar -- but ya gotta have a good roofer
with a good crew, both of  whom are used to working with coal tar, an owner
with deep pockets who realizes that this is a place to spend money, and you
don't want people too close to the work area--it stinks like hell.  The good
thing about coal tar is it reliquifies again in heat (i.e., summer), allowing
any defects to heal themselves.

There's a very large area of exposed coal tar roof on the Toy Center, which
nobody's ever reroofed, that's gotta be 80-90 years old; Senior (that's
][<en's partner at ARWNY) and I were told that it's never leaked and is good
as new. Which can't be said for the glazed white terra cotta (or was it white
glazed brick? SSDD) in the Toy Center's atrium.....

If I were building a townhouse today, or any other kind of flat-roofed
building, I'd go for coal tar.  For a pitched roof, I'd probably want slate
with terne coated stainless steel flashing or a whole TCSS roof. In the
latter case, I'd want to prequalify the hell out of contractors to make sure
they'd done TCSS before and that the owners and archts were happy with the
work.

Milner's office told me at the time BBH's TCSS roof was being installed in
the mid-late 80's that they had good tin knockers in Phila who could do good
work with TCSS, so we wound up with a local low-bidding sub to a low bidding
broker pretending to be a GCS.  Not a recipe for success.  As noted
previously, this roof (which has very low slope, large flat valleys, and
millions of penetrations) is about to be demolished and replaced with copper
over some sort of membrane.

Ralph