Sewer smell in house

Biffoland

I’ve a terrible sewer smell in my house for most of the last year. The smell is in the cavity of the house and is coming in to the downstairs rooms through the holes for the smoke detectors. The smell tends to move around, sometimes in the hallway, sometimes in the living room and sometimes in the kitchen. 

The smell isn’t coming from any drains, sinks or toilets. I’ve had a leak detection specialist in and he confirmed there are no leaks, the pipes in the house have been checked with cameras and no blockages or obstructions were found and a smoke test was done and the plumbing was found to be airtight. There’s no obstruction in the vent stack coming from the drains.

it went away for a while mid-September and has come back since Christmas. Can’t think of anything different that happened during those time periods. There’s no real link to weather conditions except it comes in strong after heavy rain.

I’ve been told I can’t insulate the cavity as the house has a timber frame.

Has anybody any ideas on where to go next with this as I’m really tearing my hair out with this.

Yellow_Fern

It might be hard for most people online to say more than a leak detection specialist who visited the site can say, but is the soil pipe external or internal? There is no chance exhaust is being blown inside from the soil pipe's vent? Is it high enough above your highest window? I have experienced that before and it can be nasty. Do you know here the pipes all are behind the plasterboard?

standardg60

Have you been having any rodent issues at all?

10-10-20

What age is the house OP and are you in an estate?

You might need to work out, by getting an extensive drain survey, whether any common sewer pipes travel under your property.

It can happen that a shared main pipe isn't accessed from your drains but yet is build over and has suffered from a failure or movement. Such a survey should also identify whether there are any unused branches which were incorrectly terminated before your build.

If you identify such pipes, then you should be able to locate the owner and chase it up that way.

chooseusername

Does your rainwater or any of your neighbour's drain into the foul sewer ?

maestroamado

I am guessing but good chance not proper gullies for rainwater...

Yellow_Fern

https://www.boards.ie/discussion/comment/118470366#Comment_118470366

Could wash basin sinks draining to rain gutters cause this?

maestroamado

I do not know what i was thinking but i should not have mentioned rainwater in my post... normal gullies from house have a water trap to stop smells coming back up the pipes... rainwater usually goes to different area in one-off housing but i expect it varies...

Bargain_Hound

We are currently Going through something similar. I think I have narrowed down the issue to the internal soil stack that runs up through our house in a stud built to carry the pipe work. The downstairs bathroom carries this pipework stud and there is a small opening where other pipe work uses the same stud, and from here a foul smell emits from time to time. It comes and goes. In addition to this, I have noticed from time to time the external drain access (where the vent stack closely aligns) builds up with sewage waste, causing a bad smell which then leaks back into the property through what I am assuming the internal vent stack. but I am unsure if this is happening due to bad design where multiple junctions coming from the house meet or we may have a blockage further down stream. Next steps for me is to figure out the cause of the buildup on the drain access.