Advice and help regarding leaking toilet

27 May 2015
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United Kingdom
Hello All,

I am in a deep mess now and I hope someone can give me sound advice.

We just moved into our first home a month ago. Before moving in we had a non load bearing wall between the toilet and bathroom removed by a builder to create a bigger bathroom, followed by tiling of all the walls and floor . The sink, toilet and tub were reused since they were a new installation(done in 2012).

Now, the toilet when refitted developed a slight leak in the toilet seal which could not be noticed till yesterday. Surely it was leaking, however water was not visible probably due to the water finding its way through the tiling onto the paster board below on the false ceiling below the toilet(which is the ceiling of the kitchen). The leak became evident when a wet patch developed in the corner of the staircase 2 weeks ago, on the common wall with the bathroom. Today I noticed that the kitchen ceiling is become soft to push and press and I cut a hole through the crack and felt the ceiling board (plaster board ?)is become soft and probably wet.

I have told my builder to fix the leak and he has agreed to do that. However, he has said to me that the wet ceiling will dry up by itself with small holes cut through it. I am unsure if the issue can be fixed so easy since the ceiling and the joists have probably been subject to this wetness for about a month now.

Would all of the kitchen ceiling need replacing? Also, should the ceiling void be treated with anti mould etc and the joists be checked? Should I leave an inspection hole to check if the joists have dried up correctly. Please remember that the cause of wetness is waste from the toilet

I have attached some pics to see. One thing which delayed the discovery of the leak so much is that the kitchen ceiling does not have a single damp spot on it though it does seem to have become damp.

Any help appreciated.
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Get the toilet leak fixed, take down the kitchen ceiling (or a section of it) and leave it off for 3-4 weeks for everything to dry out. Then replace the plaster board and re-plater.


Thanks for getting back to me Andy. My worry is more of mould growing in the ceiling void after the ceiling gets closed. Also, is there any anti mould treatment I need to apply. Also , should the ceiling plaster board be replaced totally since it is wet and maybe if it does it not dry out correctly could let mould grow in the void.

Do the joists need to be checked and is there something I can install in the ceiling to check if the toilet is leaking again...

Any help appreciated.

The plaster board will need to be replace where it got wet.

As long as the faulty plaster board is removed and the void is allowed to dry out then all will be ok, you can buy anti mould spray from Tesco's but not really needed.

The timber joists will be fine.

You can buy some drain dye from toolstation:

Pace a small amount in the toilet cistern and flush the toilet, any leaks will some up. Do this once the ceiling is removed.

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Thanks for responding Andy . I was thinking of actually replacing the whole kitchen ceiling with ceiling tiles on a suspended frame from the joists. I cant give the frame too much depth because it will reduce ceiling height. The purpose of using ceiling tiles is so that I can close most of the void and leave some tiles out for airing the ceiling void.

I also feel plaster board was the main reason the leak was not detected a month ago when it started.

What do you think.

I was thinking of using this:
Don't use ceiling tiles, it will look like an office.

99.9999% of ceilings are plaster board.

Stop being paranoid and just do as the man tells you.
Hello Andy and Jo,

Thanks for your responses. I have removed the ceiling now and the joists seem ok though I do see the black line on the joist next to the wall. There were also leaking isolators which were replaced.

Should I get the joists checked by someone else? Also , after the joists dry up, I plan to apply anti rot treatment to the joists - I am guessing this should be ok to do.

Do let me know your thoughts.


Would anyone be able to tell me if the joists need to be inspected or shall I just leave it to dry.
Just leave it to dry out. It'll be fine.

Would anyone be able to tell me if the joists need to be inspected or shall I just leave it to dry.


They are fine...stop panicking they will dry out soon,,,but if you really want to I will come to yours and tell you its ok for 2k

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