A pipe sticking out the side of a building should raise a red flag. This 1½” black pipe is a plumbing vent from a bathroom renovation in the basement. These vents are used to exhaust flammable odorous methane gas from the sewer and should always be vented above the roofline.

Please be aware that some modern furnaces and hot water tanks do vent out the sidewall of a home, normally they will extend beyond the wall with an elbow facing toward the ground.