Over the last 30 years or so with our 1926 plaster/lath walls, I have
learned to just do it, plastering, that is. Over that time there have
been cracks large and small, loose sections of plaster which grew when
I started to remove the loose stuff, and electric boxes and wires added
which required purposeful enlargement and creation of holes. I have
enough old lath to allow replacement of bad pieces when necessary.
What I do is remove enough from a crack to get loose stuff out and
hopefully expose some of the lath along the crack, too.
Then the key is, I think, to use quality Gypsum plaster as a rough
coat followed by the Diamond white finish plaster. I always keep on
hand a bag of each stored inside plastic bags; it seems to keep quite
well. This plaster is purchased at a place which supplies plaster and
materials for professional use. I would advise against using the
hardware store stuff, since it is usually a fast setting diy kind of
plaster which is probably suitable for small holes, but not serious
work.
When I run into areas in a wall which are really bad, I try to remove
up to an area with good plaster even though it may have some keys
missing. Then I wet the lath and push the Gypsum plaster underneath the
loose plaster as much as possible and work it in tight to the exposed
lath. By the way, using new Gypsum plaster gives an extremely good bond
to the lath itself plus their are new keys that are created.
I'm not perfect at this, but with practice I continue to get better,
and it fits the character of the old house.
There are areas in our house which used to have large serious diagonal
cracks, and after 5+ years since repair are still looking extremely good
with no recurring cracks. But old houses with wood beams continue to
sag, and it is not surprising to have cracks continue to occur.
Would sheet rock be any better? In some large areas I have gone that
route coupling into plaster. But I doubt that sheet rock will resist
cracks much better than well done, high quality, plaster repairs. --Phil

"Zemedelec" wrote in message
...

I bought a house 120 years old with quite a few cracks in its
interior plaster (under 8+ coats of paint.) The previous owners
did some patch-ups, but now the cracks are surfacing again. Is
there any way to have a more or less permanent fix (I'd sett;e for
20 years or so} without tearing the plaster off and doing the whole
thing over again?

--
Phil Munro Dept of Electrical & Computer Engin
Youngstown State University
Youngstown, Ohio 44555