Your plumbing vent is the pipe into which all of the grey water (wastewater) empties and is carried below your basement floor and ultimately to the City sewer. This pipe connects to the City sewer at the bottom and extends up through the roof at the top. The pipe coming through your roof is open. It is left open to vent the odors and gasses from the City sewer and your grey water pass up the pipe. Plumbing vent ice blockages can form in the winter when the warm moist air from this pipe freezes at the top of the pipe casing a plume of ice and frost to develop. This will eventually block the pipe.
This usually occurs when the outside temperatures fall below -20 Celsius for an extended period. The frozen air is so dry it freezes the air coming out of the plumbing vent the moment it escapes at the top causing the plume to develop. Blocked plumbing vents will cause the smell of the sewer as well as the explosive methane gas to enter your home and accumulate. If you detect a sewer smell your plumbing vent may be totally or partially blocked.
This will also tend to introduce backpressure in the plumbing system which may cause the pipes in your walls to rattle slightly and sinks to drain more slowly. If this happens give us a call. Our workers are trained to safely climb your roof in the winter to remove anything ice blocking your stack. Once cleared of ice everything should go right back to normal.