Waste pipe to soil pipe leak

[iluap]

Hello,

Thanks to a damp patch in the kitchen ceiling I found out the connection from the sink/bath/shower to the soil pipe is leaking. As you can see in the picture they have used a massive amount of white silicone/sealant to try and prevent what it actually ended up happening: the sealant has degraded and it started to leak. The soil pipe is boxed in and there is virtually no room for manuevre to try and pull the waste pipe back off the soil pipe and remove all the silicone and use a better approach. Even removing the silicone at the joint is going to be a nightmare. There is a beam at the back of the white waste pipe (where the top of the picture is).
My question is: can I use an epoxy seal once I remove the sealant and the area is dry? Is there a better approach that does not involve removing the bathroom floor? I am thinking creating mixing the two parts and shape a string that I can then press against the joint, where the current sealant is.
Thanks in advance!

 

[terryplumb]

Is there a crack in the grey fitting, just below the white silicone,or is it just a reflection/ shadow ?
Can you take a pic from further away ?

 

[iluap]

No cracks in the fitting as far as I can tell: what you see is where the two parts are factory-melted/joint together at origin. Unfortunalety there is very little more space I can work with, I cannot take a further-away picture that would actually show the issue.

 

[terryplumb]

Manufacturers joints are perfectly straight lines ,not zig zag like ,as appears in your pic.
Your pic is clear ,it's the orientation I want to see.
I.E. is the grey pipe horizontal or vertical ?

 

[iluap]

The grey soil pipe is vertical, the white waste pipe is horizontal. I attached more pictures showing the location, I hope it's clearer. The first picture does indeed look like a zigzag but it is straight, check the pictures below. In the close-up picture you can see two drops of water at the bottom of the joint. I am pretty sure the issue is with the silicone/sealant that has degraded and it's failing to conatin the water.

 

[terryplumb]

Looks like you will have to cut out more of the plasterboard for access, and cut out the white pipes,remove the Tee and silicone ,and make a proper joint.

 

[iluap]

I wish I had more accessdo but there is a wooden beam right behind the white pipe, as in I cannot pull back. I am attaching a very crude diagram as if you were looking at it from above.
I guess you are saying epoxy is a bad idea and I'd need to redo the Tee connection and into the soil pipe, correct?

 

[terryplumb]

You could try the epoxy ,it may work ,but for how long it would last on plastic pipes that expand and contract I wouldn't hazard a guess.

 

[iluap]

Would CT1/OB1 alternative be any good?
I do appreciate your fair advice though: better do it the proper way. However, the space I have to work is so tight that I think I am going to need a professional rather than trying myself.
Many thanks for your help so far.

 

[terryplumb]

CT1 is an excellent sealant/ adhesive,but to be frank a proper joint is the only professional way to make the joint. I have never used silicone of any brand to join a waste pipe to a soil stack, it's either solvent welded or via a rubber boss.
I appreciate the access is a real pain ,and you will need to remove all traces of the failed sealant no matter what. I suggest you do that before deciding on the way forward.

 

[iluap]

Thanks again for your help, much appreciated!