Concerning drainage/sewage smell

[Dandal88]

Hello,

For a while we've noticed an intermittent smell of sewage on the top floor of our house (we moved in here September 2024). It doesn't really follow much of a pattern, and we can go weeks without smelling it.

However - if I ever go up into the loft, it's always smelled like...well...s***! The old owners left lots of old clothes and other rubbish up there, so initally we put the awful smell down to that for a while; but it's now materialising into a constant and clear smell of sewage whenever I go up there. Also, once the loft hatch is open, the sewage smell absolutely floods the house.

Now, the soil vent pipe runs internally and is boxed into the corner of the house. Instead of protruding through the roof and venting externally, it's terminated in the loft with an air admittance valve. I'm thinking that the AAV is either letting by/failing, or there is damage to the SVP further down, and smells are being emitted which are travelling up the box into the loft.

This area isn't really my bag - and we will have a new addition to the family this year, so I'm keen to get this resolved. I've contacted a few companies, some have not got back to me, and some have said it's not something they do. What types of company could help with something like this, as I'm getting concerned and need some expert assistance.

Thanks!

 

[Harry Bloomfield]

Now, the soil vent pipe runs internally and is boxed into the corner of the house. Instead of protruding through the roof and venting externally, it's terminated in the loft with an air admittance valve. I'm thinking that the AAV is either letting by/failing, or there is damage to the SVP further down, and smells are being emitted which are travelling up the box into the loft.

The most likely cause the sometimes stuck open, AAV.

 

[ChrisJP]

Although this sort of work isn't, as you say, your bag, the simplest thing to try is just to fit a new air admittance valve. They're not expensive, or difficult to fit, and it's likely that this will fix the problem.

 

[Koolpc]

Although this sort of work isn't, as you say, your bag, the simplest thing to try is just to fit a new air admittance valve. They're not expensive, or difficult to fit, and it's likely that this will fix the problem.

This...

 

[Hugh Jaleak]

Photo of AAV would help, we can advise on which one to buy and how to change it. Otherwise, easy enough job for a plumber. I'd suspect if there was an issue with the stack below, it would be evidenced by water damage to the area around that point.