Trying to find a bathroom leak

[Plumbing_Steve]

I bought a property last year that I am now renting out. I don't have much experience with plumbing but I am learning quickly.

The tenant has phoned me up with the following:
- There is a leak from the master bathroom to the kitchen ceiling below.
- It's not a big leak. Just a small wet spot on the ceiling.
It appears to be timed with when they use the shower. When they use the shower, they notice it once every two to three times (why do they keep using the shower!) They are no longer using that shower.

Here is my plan when I arrive:
1) Touch the spot on the ceiling to see if it is wet. If it is, poke a nail into it to see if it is pooling above. If not, go upstairs. If it is pooling, cut it open.

2) Take the trim off the shower faucet. Operate the shower and attempt to see if there is any water leaking from the shower pipe or valve during operation.

3) Check the drain assembly in the shower pan to ensure it is properly sealed.

If none of those lead me to the problem, then I may need to cut open the kitchen ceiling.

One other possibility that comes to mind is that it may be a leaky roof with water following down the outside of the vent pipe.

House was built around 1988. Master bathroom was redone in the last decade.

Does this sound about right in terms of how to go about it?

Any other things you might look at or tools you might bring when trying to find a leak?

Thanks!

 

[CT-18]

Pour some water down the drain without running the water in the shower. If you get a drip then check the drain. Run the water without someone in the shower splashing around. It could be a grout issue also.

 

[Geofd]

pulling the shower plate is a good idea depending on the brand
shower valve it is (Symmons) diverter will leak behind the wall
check the shower arm and spout if its a tuba another thing
that you can do is .... standing in the tub run the water
and move around over or near the drain.... sometimes you can
test the tub without a t weight in it and it so t leak check the
strainer if it is tile the other poster is right check the grout
and tile... If its fiberglass check for cracks if its a multi
Peice tub/shower check were sections join check your waste
a d over flow plate and if you can check those connections
behind the wall .... lots of info ... I know,I just have done this
a lot Good luck

 

[Plumbing_Steve]

Thanks both!

It turned out to be pretty easy. I got on site and the wet spot on the ceiling was exactly underneath the shower drain. I took apart the drain (simple screw off) and discovered that the last guy had put the gasket above the shower pan instead of below it (and used no putty or caulking). Easy fix. Put the gasket in the right spot. Use plumber's putty. A small ring of caulk around the top of the drain screen as a final precaution.