Gully patio'd over in use

[Chester]

Hi guys not sure anyone has encountered this before but I have a job where the inside wall has been getting a little damp, there was a step up to the door that I think wasn't helping due to dpc but that was removed to take a closer look and it revealed 2 waste water pipes going into the patio floor, I went and had a look to see if leaking and couldn't directly see anything leaking but when I inspected the termination of the waste pipes they are just dangling into a gully that has been patio'd over? I'm no damp expert but could this be causing the problem, I imagine it is at least something to do with this so I am going to reroute the pipework into the stack that's nearby, I think it'll just about make it but it's not ideal at all. I've attached a photo so you better understand what I mean. I will be pressure testing the pipework just incase there is a leak under the tiled floor but I think they are 3m lengths. Thoughts? Thanks. Chester

 

[Chester]

Update, pipe on right is compromised, failed pressure test, inspection with camera can see a joint directly where the tiles begin to sound 'hollow', upsized left pipe and temp fix running everything through the 1¼ under basin as it's under a tiled floor so not an easy fix.