Advice - 40mm Solvent Weld leaking on joint to a ‘grey’ 40mm waste??

5 Jan 2009
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United Kingdom
Hi all

I had a leak from a bath waste last year and it was found to be a coupler between new 40mm PVC to a grey PVC pipe.

The white/new side from bath waste was fine but it was if the other side to the existing grey waste pipe had silicon on it and not solvent glue?

Also there was ‘pressure’ as both pipes were forming a slight ‘V’ pattern thus putting strain on the coupler.
It had been like this 15 years with zero problems.

I ended up cutting a section from ceiling.
Cutting 2 ft out of pipes and it was clearly leaking from white coupler/grey side.

I put a new 1 ft section in with 2 new couplers and plenty of solvent glue PLUS added screws as support to both pipes.
So belt and braces basically.

It now seems that it has failed again and not just a drip but a lot when emptying bath!
I’m not 100% it is the same leak as it was repaired as above but water leak is in same location in ceiling.

Could the existing grey pipe not be reacting with the PVC glue/new white PVC coupler?

I’m looking at cutting hike yet again in ceiling but can not believe it has failed tbh!!!

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Are you sure it’s solvent weld
+1. A solvent welded joint, made properly, will never leak unless it is damaged.

I have a strong suspicion the grey pipe you are trying to join to is not PVC or ABS, and so will not solvent weld. Hence previous use of silicone to try and seal it, and subsequent failure of replacement joint.
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As suggested, unlikely to be PVC, You can't use normal Solvent Weld (SW) cement to glue PP, needs PP hot glue to work properly. Were the SW couplers a bit loose on the pipe?

Use McAlpine compression couplers, replace the whole piece of pipe from the cut up to the trap so only one coupler is needed.

The problem is there is now a 2ft gap between pipes when it cut out yet again.

It was just one SV fitting. That failed.

I then cut out about 1ft to get a new sort length of PVC and 2 couplers.

Now I have to cut it again!!

If I have to use compression couplers I would be doing just the same again but obviously just with x2 compression fittings.

Unlesss they do a longish flexi coullpler?

I just did not like the thought of have compression fittings in ceiling.

I’ll post a pic in hour. So if anyone can check back/watch this thread it would be great.

Cheers all.
Did not have chance to post pics as leak was not from my repair it was from shower that has 250mm cladding.

Looks likes it’s been fixed to battens behind at approx 1 ft horizontal.
The tray is solid and smooth sunk in slightly.

When I spray jet direct at the vertical joins it’s like waterfall downstairs/through ceiling!

The waste/and where cladding meets shower base are all good.
It’s only when I direct water against the joins there are major leaks.

It’s a bar type shower with space to overclad it.

Thinking of getting two 1000mm or 800mm wide sheets and over cladding each side.

Then put shower pane/sliding doors back in place.

It also needs new rollers but I’ve seen these before on EBay etc and look east to replace.
Looks like the leak is back?

I could ONLY it to leak by directing shower head directly at the T&G panelling .

I also ran the basin/bath constantly plus filled them both several times/emptied them and no water at ceiling.

So confused now???

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