Horrendous smell from shower room. What could be the cause?

[Mr Sparkle]

My property has undergone some extensive renovation work.

Part of the work included the install of a new shower room on my ground floor.

Following the builder/plumbers works, there is a horrendous smell of sewage in the room.

So far the plumber has done the following

1. Run fresh water in the shower drain

2. Sealed the gaps around the wc waste kit (where it goes underground) with silicone.

When the toilet is flushed the smell appears to subside a little. However if a period of time goes by without flush the unbearable smell is back again.

What could the issue be?

 

[fixitflav]

I'd start by making sure the shower drain has a suitable trap, properly fitted.

 

[Exedon]

Some clear pictures of shower outlet would be useful.
Was this install totally new with new drainage or refurbishment of existing?

 

[Madrab]

Did they alter or change any soil pipework/drains?

 

[Mr Sparkle]

Yes, we had to alter sewage pipes and move the manhole as an extension was built. Clay pipes were Installed.

There was one toilet on the ground floor originally..

Following works their is a toilet on the ground floor, 1st floor and loft area.

The position of the toilet on the ground floor was changed

A new soil stack was installed for the waste on the first floor and loft area.

I will grab some pics and upload later

 

[fixitflav]

There was one toilet on the ground floor originally..

Following works their is a toilet on the ground floor, 1st floor and loft area.

Maybe when an upstairs toilet is flushed it creates a suction and pulls the water out of the shower trap. A break in the shower waste before it joins the toilet waste would cure that, if that's the culprit, and the layout permits it.

 

[Exedon]

Is the new soil pipe open vented or got a AAV on it?