A Baffling problem

[Odds]

I'd never heard of blowing gas through pipes, either, but you live n' learn. Apparently it did the trick.

At the end of the day i think you've hit the nail on the head, Denso. I've called a couple of bathroom fitters and have begun to make plans to take it out and start again...from the floor up.
I think the biggest problem for the shower tray is uneven floorboards and unaligned corners. It only takes a small misalignment to create a gap large enough for water to slip through and this old house is out of line by at least an inch.

 

[durhamplumber]

A standard bath can take 300 pounds, he was a lot more.

Andy

Is that person plus water? Does it matter whether the person is having a bath or standing/ moving taking a shower..If there is any give in a bath with a person showering it will leak.