I deal with every kind of leak imaginable. Roofs, radiators, baths, sinks you name it. The photo below is from a bathroom that was installed shoddily leading to several ongoing leaks. The toilet pan connector was incorrectly sited, the sink waste was loose, the tap connector clamp on the sink corroded meaning water getting through the loose tap/sink joint, the silicone around the bath loose, cracked tiles around the bath, and torn lino on the floor. In short, a major remediation job.
However, if the leaks are dealt with in good time the wooden floorboards and joists can be unaffected. The leaks on this job are dealt with and a few weeks wait will tell what the state of the wood is.
The ceiling in the roof below will need some minor repairs and repainting but I like to wait a month or two after the leaks are repaired to allow it to dry fully.