House smells awful - soil stack help please!

[dave41]

Hi everyone,

We have an issue where the kitchen smells like bad drains as this is permeating the house. We recently extended the kitchen into the old bathroom utility room (in the process capping off old washing machine, toilet, shower, and sink) and this is when the issue started. The floor is not fully back down yet, and the void under the floor noticeably smells awful and so I'm thinking there's some kind of leak from the soil stack itself.

In trying to troubleshoot the issue, I can see 3 joins which could be the issue... photos/videos and a drawing below!

A - What I believe would have connected to both the old toilet and washing machine. This rotates easily seems a bit loose - could this be causing a smell?
B - What connected to the old shower. Seems like a fairly sturdy connection? Now temp connection to washing machine - see below.
C - What connected to the old sink. Very difficult to access this but can't see anything wrong?

So my hunch is joint A is the issue, but could this looseness really be causing the bad smell on its own?

Other theory is there's a blockage somewhere? But would that really cause the void to stink?

Final theory is the washing machine has now been temporarily plumbed onto B (photo also attached). We covered the top when we first got smells as we initially assumed it would be from that being open. But now I've read about AAVs, and I wonder if this is contributing to the problem?

Advice, theories, suggestions all massively welcome. I can take more photos as needed!

 

[CBW]

Drain smells are usually the sign of an open end or trap seal loss. I’d be checking the washing machine trap and maybe get a drain cap for the toilet connector, ventilate the room and then see if it’s comes back.

 

[dave41]

Hi again Chris! Thanks for your response, by checking the washing machine trap what exactly do I need to look at?

On the toilet connector (which is the one I sent a gif of wiggling) there is a drain cap on (the black thing under the hand, right?) which has been sealed with extra sealant as our builder initially suspected that.

 

[Harry Bloomfield]

Hi again Chris! Thanks for your response, by checking the washing machine trap what exactly do I need to look at?

That there is water in the trap, to form a seal. No seal will allow foul air from the sewer out..

If the trap is emptying, then you need to determine why.

 

[CBW]

Hi again Chris! Thanks for your response, by checking the washing machine trap what exactly do I need to look at?

On the toilet connector (which is the one I sent a gif of wiggling) there is a drain cap on (the black thing under the hand, right?) which has been sealed with extra sealant as our builder initially suspected that.

Hi Dave, I wasn’t sure if it was a bin bag used, so that should be ok then if a drain cap has been fitted. As per @Harry Bloomfield for checking the washing machine trap, maybe remove the tape and bags, look down the pipe to see if water evident at the bottom of the u bend.

 

[dave41]

Thanks both, just removed all the tape and bags to check - there's plenty of soapy water in the trap from the washing machine.

And the old sniff test says it all smells fine out that end too.

It does seem like the smell is coming from around junction A, but I can't get very close to either of the other junctions to smell them, so it might just be the whole void smelling.

 

[CBW]

Was the old washing machine waste capped off?

 

[dave41]

I'm not sure. Junction A is in line with where both the old toilet and the old washing machine were. So given I can't see any other junctions, my current assumption is that BOTH somehow fed into Junction A through the hole that now has been capped. Would that be possible or is there some other hole in the soil stack I haven't identified yet?

 

[dave41]

I just realised the utility room had a sink in it too, so there were a total of 5 appliance draining into that soil stack: shower, bathroom sink, toilet, washing machine, utility sink.

There are only the three junctions in the stack so the only sense I can make of it is that the utility sink, washing machine, and toilet ALL drained into Junction A. Unfortunately I didn't see this before it got capped off, but would that set up be likely or am I missing something?

Void still smelling pretty bad - is the movement in Junction A normal or does it need to be resealed somehow?

 

[Madrab]

Seems you have a couple of options -

1) pressure test the stack though that may be moot as there are obviously sections that are not sealed properly
2) smoke test the stack, that will show up the areas that are passing and allow a more focused fault finding process.

The only other alternative is to replace sections that are obviously compromised and take it from there.

Movement in Junc A - if it is a push fit branch into a single socket then the seal is compromised/missing in the socket as there shouldn't be that amount of movement. Is that in the floor or is it the wall, can't quite tell from the GIF tho it does look like the former. You may have to open up sections of the soil run to get a better idea.

 

[dave41]

Thanks Rob. I'm guessing to run a smoke test I'll need to call in a professional, as the videos I've just watched of smoke testing all require specialised bits of kit. I have access to a "party" smoke machine but I don't think I could send that down the drain properly.

Re: junction A - if that's compromised, could that alone be causing such a bad smell in the void? I've noticed the smell is definitely not as bad in the house when the floor boards are down, but as I was trying to investigate yesterday and left the floorboards up the house filled up with the smell.

If junction A alone is the cause of the smell, could I apply sealant on both edges to seal it up? Once our works are complete this entire bit of soil stack is going to be redundant, as the washing machine is being moved elsewhere. so when we get to that stage, I'm thinking we can cap off the entire run.

 

[dave41]

Hi folks, any further thoughts on this please? If Junction A being compromised could be the cause of the smell I’ll try sealing it up today - what’s best for that job? I have an all purpose sealer but wonder if something different is better

 

[Nige F]

Fernox

Hi folks, any further thoughts on this please? If Junction A being compromised could be the cause of the smell I’ll try sealing it up today - what’s best for that job? I have an all purpose sealer but wonder if something different is better

Fernox LS-X

 

[Madrab]

If it were me and it's temporary, I'd use a polymer silicone adhesive like wet grab or similar. It sets to a firm rubber finish - move the soil pipe back a little, a layer of the adhesive and the push back into the fitting then smooth all the way around and leave dry and keep stable for 24hrs.

 

[Hugh Jaleak]

If Junction A is now redundant, I'd be looking at removing it completely and grafting a new section of pipework in to replace it. I would be concerned about that amount of movement, and there is a distinct possibility of a leak, air if not water and/or both.