Plaster behaves different than drywall: it’s harder and more brittle, so when framing moves even a little—like what can happen with minor differential settling over loamy alluvial soils with caliche layers—the plaster doesn’t “give,” it fractures. Then the extreme heat and UV bake the building, materials expand in the day and cool at night, and you get those classic spider cracks, popped corners, and loose (hollow-sounding) patches. During monsoon flash-flood bursts, moisture can sneak in around windows/trim and soften old plaster keys or lath areas, which is when chunks start to delaminate. We also see seasonal shifts: summer movement shows up as long hairlines; cooler months tend to reveal the edges of prior patches if they weren’t sealed right. The durable repair is re-attach loose plaster, reinforce cracks, float with the right compound, then prime/seal so it doesn’t “ghost” through paint—materials for this are usually easy to source locally, but matching old textures is the real craft.