There may have been leaks from the floor of a shower cubicle, because of a water stain showing on the ceiling of the room below.

Can I rule out water (when the shower is being used) seeping through cracks in the grouting between the floor tiles?

 

Is there a water-proof membrane under the tiles, or could the tiles just have been glued to plywood boards (which form the surfaces of all our upstairs floors, covered by carpet or tiles)?

Does the plastic, or plastic-like, square fitting around the circular drain hole extend under the tiles?

The dimensions of the cubicle floor are 86cms by 94cms, so does that approximate to the size of a continuous water-proof membrane (which I suppose could have been cut down to fit the dimensions of the floor)?

 

Here are photos of the cubicle floor, continuous with the floor of the bathroom, and close-ups of the fitting around the drain.

 

Thank you.

 

 

 

 

 

 

 

 

That looks like a wet room so if it was done properly there would have been a proper tanking membrane on the floor and lapped part way up the walls before the tiles went down.

 

So most likely a leak from the waste pipe? 

@ProDave, thanks, yes, I agree, "if it was done properly"!  🙂

But unfortunately since moving into this house which was built 12 years ago we have been challenged by quite a few things which definitely were not done properly.

So I can't have faith that a proper tanking membrance was laid and that it lapped part way up the walls before the tiles were put down. 😞

 

I was hoping someone might be able to tell by examining the plastic or fibreglass fitting around the drainage hole.