How quickly the landlord must respond
A landlord must fix structural damage within a reasonable time after being notified, and anything dangerous — a collapse risk, a failing stair or balcony — should be addressed right away, not left for days or weeks.
There is no single deadline in the law, but the more dangerous the structural problem, the faster the landlord must act. A hazard that could cause injury calls for an immediate response, while a less urgent, stable structural repair may reasonably take a bit more time to arrange, since these repairs can be complex.
What is not acceptable is leaving a real danger in place while nothing happens. Report the problem in writing, note when it started, and follow up. If a building inspector gets involved, their orders may set their own timeline. If your landlord lets a dangerous structural problem drag on, a free review can help you understand your options.
This is general information about California tenant rights, not legal advice. Every situation is different.