Why Stucco Cracks in the First Place
Stucco is rigid and cement-based. That makes it durable, but it can't flex much to absorb building movement or thermal expansion. It's the same daily expand-and-contract stress covered in our thermal cycling article, acting on a wall instead of a roof. Because stucco can't absorb that movement the way a more flexible material could, some cracking over time is close to inevitable, even on a well-installed wall. Keep that in mind before assuming a crack means a serious problem.
The Normal, Cosmetic Kind
Hairline and spider cracks are thin, typically under 1/16 inch, and often form a fine web-like pattern or single thin lines. They're generally caused by normal curing, minor shrinkage, or the same thermal cycling that affects every exterior surface in this climate. They're cosmetic. Patching them helps keep moisture out over time, but they don't point to a problem with the wall or foundation underneath.
The Kind That Deserves Attention
Diagonal cracks originating from window or door corners are a different story. These often point to foundation settlement or structural movement instead of routine wear. Cracks wider than about 1/8 inch, especially ones that are deep, jagged, or growing over time, cross from cosmetic into structural territory. Any crack with staining or visible moisture is worth attention regardless of width, since it means water is already getting past the surface.
How Storm Damage Looks Different From Both
Hail-caused stucco damage has its own pattern, different from both normal cosmetic cracking and settlement cracking. Hail strikes a wall's exposed surface fairly evenly instead of concentrating stress at specific structural points. So storm damage tends to show up as widespread impact marks across the whole exposed area. You won't see the corner-concentrated diagonal pattern of settlement or the fine web pattern of ordinary cosmetic cracking. This matters for the same reason it does with roof hail damage (see our hail damage article): separating storm impact from pre-existing wear is the kind of assessment that should happen before deciding whether a claim makes sense. A wall that already had scattered hairline cracks before a storm can also take real hail damage during it. The two can happen together, which is why pattern and timing matter more than whether there are cracks at all.
What This Means Practically for Homeowners
- Measure before you worry. A crack under 1/16 inch with no staining is almost certainly cosmetic, regardless of how it looks at a glance.
- Pay attention to location, not just width. Cracks radiating diagonally from a window or door corner deserve a professional look, even if they're thin.
- After a hailstorm, check for widespread, evenly distributed marks along with isolated cracks. The pattern itself tells you a lot, the same way it does in a roof hail assessment.