Dave Page wrote:
I am trying to fix a plaster / lath ceiling. Near one corner, a
section approximately 2' square has fallen out, and the rest of that
corner is sagging visibly. It looks like the plaster has become
detached from the lath there, but the lath and joists seem solid. I
have a few questions about effecting a repair.

* Is it practical to only repair the damaged area? One option I was
considering was removing the sagging plaster and screwing plasterboard
into the joists below the sagging and the hole. However, it seems a
reasonable assumption that if one part of the ceiling is damaged, the
rest will be soon.


Correct.

* Is it possible to screw entirely new plasterboard over the sagging
plaster, and the hole, and the existing ceiling? This seems perfectly
possible from reading
http://www.diyfaq.org.uk/miscellaneous.html#repairing and similar, but
the problem is that the existing ceiling has stippled plaster.

It doesn't matter if it's stippled or not, plasterboard screws come in a few
sizes and anything less than 3 inches is a POP*


* Regardless of which option above is best, is it cost-effective to do
the plasterboarding myself and then pay a plasterer to do the
skimming, or should I just get the plasterer to do the whole job if
I'm not planning on skimming it myself?

Better to ask individual plasterers, some want the boarding some don't, if
you lived near me and you boarded it and supplied the scrim and plaster I'd
do it for £100.
Expect to pay a plasterer £200..ish for supply and fit.


*
Piece Of P1$$