Greetings,

I live in a relatively new home and over the past few months I've noticed a mild sewage smell in my 2nd floor bathroom. The smell does not seem to be coming from anywhere in particular. I have noticed that on windy days the smell is more noticeable. The water drains fine in all cases.
Recently I noticed a strange sound coming from "somewhere" around the base of the toilet close to the wall (inside the wall?) as I ran the sink tap. It sounds as the though the water is dripping onto something or down something - almost as though the vent pipe is completely (or partially) disconnected. I have not noticed any leakage anywhere.

Anyone have any thoughts?

Thanks,
Sean Mckaig

Sorry Sean,

Smells and intermittent noise are the hardest to figure out unless you're on site when they happen.
For the smell I would install a vent cap,( see image) on the bathroom roof vent to discourage backdrafts that may be making their way into your bathroom.

As for your sound, the lavatory drain's connected to the soil stack behind the toilet so what you hear is the water draining down the stack. Cheers, Tom