I bought a post-war story-and-a-half about a year ago. It had some minor
water damage, due to ice-dam roof leaks that are so typical of the
design. A new roof was put on, about five years ago, and when I bought it
the inspector said the interior was bone-dry. But the plaster ceilings
have a few cracks and some sloppy patches, made more obvious by a poorly
applied textured ceiling.

I "fixed" one bedroom by scraping the popcorn, fixing the cracks with
chisel, tape, and compound, sanding, priming, and painting. I'm not
really happy with the result.

I've been looking at the second bedroom, and considering my options. I'm
leaning towards laminating with 1/4 drywall.

The existing ceiling is built on rock lath, and it's solidly attached.
I don't see reason why it should need to come down. The problems are only
cosmetic. Beyond that, it's level and flat. I skimmed a laser-level over
the surface, and aside from a bit of protrusion where the patch was done,
it seems to be at least as straight as I could manage to get with firring
strips.

It seems to me that that the drywall would cover a multitude of sins, but
that that lumpiness is the one it could not cover. Cracks and depressions
would not force the drywall sheets from lying in plane, but a lump would.
Not just force the drywall out of plane, but tend to pull the edge of the
board so as to make an uneven joint.

So I plan on sanding the patch down until it's in-plane again, and then
rent a drywall lift and screw the panels into place. I'm anything but a
fast worker, but I think I can manage to get eight panels in place on a
single day's rental. Jointing I can take my time at.

I have three main questions.

1: Is this a reasonable way of dealing with the problem? The existing
plaster is firmly in place, it seems absurd to go through the work of
tearing it out simply to replace it with a lower quality substitute like
drywall.

2: What fasteners should I use? Drywall screws? Drywall nails?
Something else? Through the plaster into the joists, of course, but how
far apart? Should I add additional fasteners along the edges between the
joists? In the interior of each panel, not along the joists?

3: How do I treat the corners? Run joint tape and compound along the
valley?

Help would be appreciated.

--
Crime is not only a complete disavowal of the social contract, but also
a commandeering of the victim's person and liberty. If the individual's
dignity lies in the fact that he is a moral agent engaging in actions of
his own will, in free exchange with others, then crime always violates
the victim's dignity. It is, in fact, an act of enslavement. Your wallet,
your purse, or your car may not be worth your life, but your dignity is;
and if it is not worth fighting for, it can hardly be said to exist.
- Jeffrey Snyder