Leak in kitchen - is soil pipe the source?

[Bearino]

Hi folks,

I've been having issues with a leak in my kitchen for some time. Reached out to insurance who were not useful, and several trades have either not resolved the problem or didn't want to get involved.

Currently it looks like this: Leak site after insurance investigation

Insurance broke through the plasterboard to try and find what's behind, a soil pipe. Have attached an image and video of the exposed soil pipe.

This is in a flat roof extension to my kitchen. On the right of the beam is the original house, and directly above is the toilet.

Above this, on the roof you can see that the vent pipe leads into a box. The box is directly behind the toilet. The box is sealed, originally with felt, and then the insurance guys covered it with some strange sealant that's now started peeling: The "box"

Inside the box: Soil pipe coming out of the toilet, covered in bitumen

Inside the box is the soil pipe. It's a strange angle, and it's been suggested that it might be ceramic. It's also covered with something horrible, bitumen perhaps.

Close inspection of the pipe showed that it seems to have slipped, there might be as much as an inch gap between the pipes, but the bitumen is hiding it: Signs of slippage

What I suspect is happening is the box itself is sealed and weather tight. However, within the box, underneath the pipe, is not sealed. The pipe is leaking straight into the house. I've so far had difficulty getting this fixed because it needs the roofer and the plumber to work together.

Given this, I'm thinking that I should crack the box, remove the pipe, and seal the roof underneath the pipe so that I can remove the box. That gives me free access to the plumbing and a plumber can fix it without the pressure of getting a roof weathertight.

I have a number of questions I hope people can help with:

1. Is there a reason that the pipes would have been covered in bitumen?
2. Is there a good reason for building the box around the pipe, rather than sealing the roof underneath it? I presume it might be because replacing the roof is going to be difficult with the pipe in the way.
3. Should it be possible to erect a tarp to keep the area dry, or am I going to have to time this around weather?
4. Is felting this sensible given I have no experience with a torch etc? The box is less than 0.5m², is there another option that would be easier given my lack of experience? I'm considering just cracking the box then sealing the edges with epoxy as that seems to have worked for the insurance roofers...
5. Do I need to give any consideration to the state of things within the box eg sodden wood?
6. Can you make any sense of the soil pipe exposed in the kitchen? There's a strange mass around it and I'm not sure if I should be opening this up further as a possible second leak

Thanks all

 

Edited October 28, 2023 by Bearino

[Crunchynut]

Hi @Bearino

 

Your post has lots of views but no replies yet - I guess, like me, people don’t know where to start, because you have a right mess on your hands there.

 

It looks to me that because the toilet soil pipe comes through the outside wall at roughly the same level as the flat roof, they have built a ‘waterproof’ box over it because the pipe spoils the ability to properly cover the roof in that location. But it looks like it has been done very badly (sorry to offend if you or yours did it) and was always destined to be problematic.

 

I would say that anything you do to ‘patch it up’ is going to fail within a short space of time because you have nothing  decent to work off.

 

The bitumen on the pipes is probably a crude way to try and seal everything up and prevent leaks - just daub with bitumen in a ‘spray and pray’ kind of fashion.

 

Tarps work to keep a central area dry but water always gets round the edges in my experience. And it only takes a bit of water to make everything wet. So, for example, if you were just to butt the tarp to the wall of the house, water will get behind. It will be better than nothing of course, but not a solution. In the past when I have had to do this I have used ‘flash band’ (roll of aluminium about 5” wide with tar on one side that you heat up and stick down with a blow torch) to seal between the wall and the tarp, buts it’s all quite precarious.

 

You can re-box it but you need to properly flash the join between the box and the roof. By that, I mean the roof covering needs to lap up the sides of the box and then the box covering needs to overlap the ‘turn up’. Difficult to do with felt since you will have a lot of joins and laps and felt cracks quite easily either straight away or soon after once the weather gets to it. Buying a prefabricated box might be an option.

 

Points 5 and 6 - I’d say you need to rip all of that area out because it will never be any good. The wood will rot and the damp smell will pervade. The mass on the pipe might be someone just having stuffed in something absorbent to stop a leak, or perhaps prop up some felt.

 

If it were me - I would look at putting a new soil pipe on the toilet, run it through the wall and then straight down into the roof, you can get flashing collars specifically designed for sealing around pipes in this configuration so a good job can be done. Then inside, properly connect the pipe into the existing stack and make good with new stud work and plastering etc.

 

Sorry if that’s all no help - the situation isn’t entirely clear - but I thought I would try and reply.

[Jilly]

If you can’t tackle it yourself you might need a small one man band type builder who can turn his hand to most things or who has contacts he works with (try to get recommendations from friends for someone good/reliable/trustworthy) to come up with a solution as @Crunchynut has suggested, rather than trying to get a plumber and roofer to work together. You might find it difficult to get a price as they don’t know what they will find. Hope you have another toilet for now…