What causes plaster to crack between the wall and the ceiling?
I saw other good answers here but thought these extra points may be valuable… YES, normal expansion and contraction of building-materials CAN and WILL cause cracks. However, those forms of cracking happen over long periods of time; typically decades. If you are noticing a sudden appearance of new cracks, especially large ones, then there are probably other mechanical causes. Such causes could include: Stresses from increased wind or storm activity, Mechanical load-shifting, such as moving a piano, pool table or heavy machines within a home. Failure of insulation systems so that drastic invasion of moisture causes severe expansion. Seismic activity… Do you live in an Earthquake zone? or Near a busy highway? Heavy truck traffic can cause some of the same foundation-shifting damage that minor Earthquakes do! Tree roots. Do you have several large trees on your property? If so, then roots can damage a foundation in just one summer. If you rule out all those potential causes, I suggest y
