I recently moved into a very old home in Chicago and now part of it smells like garbage.
The home is two stories + basement, 130+ years old, and is primarily brick, but the back has an addition that is primarily wood/siding and is several decades old (I don’t know exact age). When I first moved I occasionally noticed a slight smell emanating from the back of the house in in the basement/first floor (often after rain), but it stopped once winter came. The smell is something mixed between garbage and dead fish.
We’ve had a warm couple weeks and after all the snow melt I’ve noticed the smell aggressively returning. I investigated and noticed it was coming out of a wall vent in the back of the basement (wall vent connected to ventilation along exterior wall) and a floor vent in the back of the first floor (I think drawing off same vent as basement wall vent). I checked the back of my house under the deck and discovered the external wall appears to have very old siding and even just worn out planks of wood (pictures attached). I also noticed what appears to be an external vent (green circle in last picture) and what appears to be a protruding sewer drain (red circle in last picture, I think a downspout used to feed into it).
Seems like the worn siding is likely letting moisture and needs to be repaired, but also the vent + sewer drain are probably the main issue?
I’m not really sure who would even fix the sewer drain/vent issue.