My new downstairs shower room/toilet builds up a drain smell overnight or if left unused for some time. The flow to the main drain was just about the minimum the inspector would allow but it all seems to flush ok. The shower and the sink are also tapped into the vertical pipe that was left cut off by the builders as i was going to final fit the room. The pipe has a Durgo valve fitted on the top and is boxed in but not sealed. The tee for the shower and sink are below the Durgo.
Could the smell be coming from the shower/sink and does the fitment above sound right. Should i expect to get the smell from the Durgo ? I know you can use these inside but surely the air will smell and it has to escape in the room. I could cut into the wall and vent externally ( don't know why the builder didn't do this anyway ) but i don't want to damage the wall and redecorate.
There is an external soil stack on the opposite side of the house and the drainage meets at the front of the house and out to the road. Could i do away with the Durgo and cap it ?