Is your plaster cracking?
This is actually a very common problem, especially in wood framed houses.
Before we get into the reason your house plaster is cracking, realize that home plaster walls and ceilings can be repaired.
Plaster is not a very elastic material, especially in wooden houses. There isn’t much “stretch” to plaster– it will break. Several
forces can work against the integrity of plaster, leading to subtle
movement in the house structure. This stress shows up as cracking or
buckling in the wall or ceiling plaster.
In many wood-framed houses, the lumber used for construction is still a little wet. Even kiln dried lumber has moisture, so wood in your ceiling joists and wall studs shrinks
over time, drying and moving. That movement can be amplified over the
years by weather changes.
Sometimes the ceiling joists old houses really aren’t strong enough
to support properly the full weight of wood lath and plaster. So they
sag and this too leads to cracking.
This is also true for houses with
wood lath backing for plaster. Again, the lath nails can loosen, causing
buckling and cracks.
Water intrusion and leaks from roofs or plumbing can wet and soften plaster. Cracks may show up as the plaster loses its strength.
One of the most popular home plaster systems since the late 40s has been rock lath and plaster.