leaking toilet

Hi I’m having difficulty to one of my duplex house. The toilet wall is leaking from the ceiling. It looks damp all the time. How can I repair it. Any idea?

Like most of your posts this is very vague.

Is it a constant leak or only when flushed?
Do you have access to the pipes?

Do you mean the ceiling, located underneath an upstairs toilet. is damp?

The first two things I would check would be the wax ring of the toilet and the water line running to the toilet. If you have to replace the line, use the metal braided lines. There are two types of metal lines. One has a large open braid and one has a braid with many small strands. The tight braid costs more, and that’s the one you want to buy. (make the repair today, never do it again).

If you have to repalace the line, it’s a good time to replace an old turn-off valve, or install one if there isn’t one.

Another posible problem is that whoever is living there is getting a lot of water onto the floor when they shower. Or they don’t use the ceiling fan, and water is condensing on the outside of the toilet and running down.

For tenants, wire the exhaust fan and the light onto the same switch, so they have no choice: the fan goes on as soon as they turn the light on.