Ceiling sagging or drooping — Barcelona, Catalonia

A sagging ceiling is both a cosmetic eyesore and a potential structural warning sign that demands prompt investigation. The causes range from harmless to serious. On the cosmetic end, old plaster-and-lath ceilings sag when the plaster keys break loose from the lath strips due to age and vibration — the plaster is no longer anchored and gravity pulls it down. This can be re-secured with plaster washers and screws ($200–$600 per room) or replaced with drywall ($1,500–$4,000 per room depending on size). On the structural end, water damage is the leading cause: a slow roof leak, burst pipe, or condensation from a poorly insulated attic saturates drywall or plaster until it swells and sags. Termite or carpenter-ant damage to ceiling joists weakens the framing. Overloaded attic insulation — especially blown-in insulation added on top of old batts — can exceed the ceiling's weight capacity. In rare cases, undersized joists or removed load-bearing walls cause structural deflection. A carpenter or contractor should inspect the attic from above to identify the root cause. If the issue is water, the source must be fixed first. Joist sistering (reinforcing) costs $200–$500 per joist; replacing a damaged section of drywall runs $300–$800. If structural repairs are needed, expect $1,000–$5,000 depending on scope. Never ignore a ceiling that is actively bulging or cracking — a sudden collapse can cause serious injury.