Can't remember whether you mentioned what the subfloor was made of?

I didn't.

The subfloor is 1/2" plywood. BUT the joists are close together and the
relatively thin subfloor doesn't seem to have caused any problems. It
seems (to me) that each floor first had plywood laid down over the joists
and THEN the walls (interior AND exterior) were constructed. There is
brick veneer on the street side and the entrance side (end unit) but
composition board on back. As built the units were/are good looking but
MANY shortcuts were taken with the details. Some joists have a LOT of wood
missing for drains. In some cases, "they" changed their minds and two sets
of holes were made in joist. But, again, the joists are close together and
the floors just don't bounce!


The "paper" easily lifts off the plywood in many places. In other places I
have to scrape. In some places (I haven't finished the job), I suspect I
will have to do some HARD scraping or even some sanding.