Stack pipe waste leak in wall - photos attached

[liam548]

Hi all, its been a few months without a leak in our fantastically built Redrow property (sarcasm)...

The latest one first got noticed when we had a little damp patch above our grey skirting between the kitchen and dining room around March time this year (an area we opened up when we moved in in 2017, took a wall out etc).

After reluctantly removing the skirting and some lower plaster a lot of damp was seen on the floor substrate and on the lower breeze blocks.

I called a local damp expert who suggested the DPC had probably been clipped when we took the wall out in 2017 and wanted to inject new chemical dpc, coat and re plaster for £750.

Coincidentally our neighbours (same house design and also done similar work to his house) noticed his skirting coming away in the same location.

Fast forward 2 months and he located a pipe in the main stack which had a 1cm hole in it, every time the main bathroom was used water was coming out of it. He uses his main bathroom a lot as they have 2 kids, ours barely gets used except the odd toilet flush every few months as we use the en suite at the front of the house. He had also had the main bathroom recently replaced so you can imagine he was confident this was linked, we had also had the rear Garden extensively landscaped late last year so equally without bouncing off each other we would have gone down various dead end rabbit holes...thankfully we had enough notice to avoid a waste of £750 from the damp expert.


To cut the story short he found the leaking pipe with the hole (no idea how or why the hole is there) and I cut a the same square ours to view the waste stack. As can be seen on the attached photos there is no hole but ours is leaking from the join to the main stack pipe that goes under the house into the ground. Clearly the fantastic Redrow contractors know how to use plastic weld, Not!

So despite both houses having wet in the same area and caused by the same stack pipe from the main bathrooms, and finding the damp within a few weeks of each other they are it seems completely unrelated!!! Very odd.

My question is what is the best way of sorting this on mine?
I've tested with running the bath, separately running the sink both cause dripping from the location in the photos within minutes. Flushing the toilet causes water in the same place but much more prolonged for some reason. In fact before cutting the hole flushing the loo a few times would after a day or so cause significant pooling on the floor at the bottom. I'm not sure why a flush or 2 would cause the water to drop for over a day from stack, surely 99% of water goes down the stack and then the odd bit that doesn't would leak out but stop pretty quickly??? Any ideas?

More importantly any suggestions on sealing the join to stop any water whatsoever coming out? Avoiding completely ripping the bathroom floor up. Fortunately it does appear to be just the area in the photos and not of the more fidddly joints higher up in the space above.

We are expecting our first baby in a week or so so the main bathroom will actually probably get used a more so could do with this rectifying asap.

Many thanks for your advice

Liam

 

[terryplumb]

You could try to use a thick solvent cement ,such as floplast. The area must be thoroughly dry first. Brush on and try to work it up in-between the two mating surfaces ( as much as you can ,which won't be a lot). Let it dry for an hour ,and apply another coat.
You are effectively aiming to create a bead around the periphery of the fitting.
There is a good chance it will seal it up.

 

[liam548]

You could try to use a thick solvent cement ,such as floplast. The area must be thoroughly dry first. Brush on and try to work it up in-between the two mating surfaces ( as much as you can ,which won't be a lot). Let it dry for an hour ,and apply another coat.
You are effectively aiming to create a bead around the periphery of the fitting.
There is a good chance it will seal it up.

Thanks Terry, this was my initial thought/idea. No point using silicone as yes it may hold for a few years but not forever and I simply cannot tolerate any more leaks or water issues in this house, over 10 now since we moved in in 2017 and the house was only built in 2007!!!

So what is the absolute best product to purchase to do this? Is it floplast?

If it stops it would there be any point/detrimental effects of adding sealant around it as a double measure after wards, and then plumbing sealing tape as a third belt and braces!? As you can tell I want this to be the last plastering job and painting job forever here haha

Thanks again for your advice.

Liam

 

[terryplumb]

Due to the close proximity of the wall ,it's not likely that self amalgaming tape,or any other could be applied . And sealant such as silicone is a waste of time.
A patch, solvent welded on would be the next option.
And yes, floplast Solvent cement is thicker than most.

 

[Madrab]

Using a thin bladed paring knife you may be able to slide it into the joint and create enough of a gap and use it to tease solvent cement into the space but it would be hit and miss.

How much gap is behind that pipe, could a rubber repair band be applied, with some silicone adhesive that could then be clamped?

 

[liam548]

I can get access to the rear of the pipe, with my hand at least. The blanking pipe to the left of the photo is pretty much too the wall though.

Would using the Floplast have any potential detrimental effects? It couldn't burn through the pipe completely could it? It does seem to be just really the front forward facing half of the pipe that's dripping I can't feel any at the rear

 

[terryplumb]

No ,the solvent cement is what is used to bond the fittings together originally.
Unfortunately yours hasn't been done properly !!

 

[liam548]

Indeed. Along with a lot of other things we have noticed.

I'll get some of the product you suggest, wait til its completely dry, clean it up as much as I can and lather it on and re test

 

[terryplumb]

It comes with a little brush to apply with ,by the way.

 

[Madrab]

Get some 240grit paper and clean up the area as close up to the joint as possible, then use some spirit to wipe clean before doing the job to give it the best chance. Run a hair drier over the section to try and dry off the gap in between the 2 pipes sections before gluing.

 

[liam548]

Still on the to do list this one and thanks for the replies so far above.

Just another question though any ideas why the dam things still dripping from the same place over 2 days since I flushed the toilet!!? It makes zero sense. There is no one using the bathroom, toilet not leaking, taps not on shower and bath dry.

Now I know eventually it does stop as when I thought it was the rising damp it did dry out eventually equally after a flush the floor got very wet with water which I soaked up with a towel around the fall pipe.

My question is logically a toilet flushing 99.5% of the water will be straight down the vertical fall pipe, any that hits the faulty neck area as per this discussion will drip down, but surely not for 2 to 3 days??

Can anyone think why the excess of water would be still there?

Obviously still waiting to completely dry before attempting the fix above.


Thanks

 

[terryplumb]

After 3 days I wouldn't expect water to still be trickling down the stack ,that's indicative of water still going in. Is the stack vented externally ,where rain can enter ?
Is your boiler condensate pipe connected to that stack ?
Sometimes a W.C. can pass water from the cistern into the pan ,at a trickle that is very difficult to notice ,check that out.
What are the other ,smaller waste pipes connected to ?

 

[liam548]

All good points Terry yes but:

Boiler is downstairs goes directly outside, the stack vent is in the loft and it has only rained today.

I hear you about the loo I did check that as the seal is not the best on the flush upstairs but double checked and toilet is stable to off.

The other two smaller waste are one goes to sink and other goes to bath neither of which are on.

It's got me confused, Id expect a surge of toilet flushing to cause more impact than running the tap and yes for it to maybe pile up a bit in the broken stack seal but as you say not this much. I'll wait til it stops and assess further..

At the min it's got a towel wrapped around the stack getting quite wet.

 

[HERTS P&D]

Come on Judge Rinder, call someone out to fit a furnco coupling.

Andy

 

[liam548]

After 3 days I wouldn't expect water to still be trickling down the stack ,that's indicative of water still going in. Is the stack vented externally ,where rain can enter ?
Is your boiler condensate pipe connected to that stack ?
Sometimes a W.C. can pass water from the cistern into the pan ,at a trickle that is very difficult to notice ,check that out.
What are the other ,smaller waste pipes connected to ?

After your post Terry I re checked the toilet very closely and yes it's got its own seperate issue with the seal, ever so slightly seeping into the bowl not enough to cause a noise hence difficult to detect.

I've turned the water off to the loo and emptied it and the dripping on the stack pipe has stopped.

Now I'll continue with the original fix you advised but any ideas what kind of toilet seal and flush this is and how I get a replacement seal?
The morons who installed it decided to put a load of sealant around rubber seal in the bottom of the toilet tank, no idea why as it flapping around and doesn't seem be doing anything.

Hopefully the photos are clear enough...

Thanks again

Judge Liam