We live in a townhouse that is about 1.5yrs old. Last night we heard a humming coming from between the shared wall- it almost sounded like an amp that was turned up really loud. Our neighbour heard it too- and came to the door at 4:30AM because he thought our furnace was going to blow, but the furnace was off for the night. The sound seemed to be loudest on their side right across from one of our bathrooms but for us it was loudest at the opposite end of the house in the basement. It could be heard to some extent though along the entire wall. I read one post about checking the flapper in the toilets. I checked and they seem fine but the one toilet in our house does run a lot and a tap has to be turned on to get it to quit. It has also snowed quite a bit here in the last few days so we thought maybe a vent has been blocked? If anyone can give me a hint as to what this might be, that would be great.
