Venting Problems in Plumbing

Plumbing vents can wear down or become blocked.

Plumbing systems use vents to allow for proper water flow, especially drainage flow for fixtures, such as sinks and toilets. Without a vent attached to the system, air caught in the flow would cause bubbles and reduced flow, so residential plumbing systems have a vent that goes up to the roof and extends several inches into the air, enough to allow air and other gases to escape and encourage the flow of waste water. These vents are subject to several issues over time.

Old Pipes

Old pipes are an issue in homes that have plumbing systems that were installed decades ago. Sometimes these pipes may be made out of cast iron and other inflexible metals. When the house settles, the pipes move too and no longer rise high enough above the rooftop to properly vent the system. Older homes may also have new roofs that cover up the venting pipe too much and cause similar problems.

Damaged Pipes

Damaged pipes do not vent properly and leak air and gases into attic areas instead of outside. For older pipes, corrosion may be an issue due to years of weather. Pipe joints can also wear down and eventually crack. This reduces the efficiency of the venting and requires replacement in order to make the system efficient once again.

Clogging

Vent pipes are typically well-protected from leaves and dirt that might clog them. But in harsh climates with frequent snow and wind vent pipes are susceptible to clogging, leading to reduced efficiency in the system. Some venting systems are wet vents, which means they also help channel waste water. In this case, the waste that uses part of the system as a drain can also clog the pipes.

Leaking Issues

Leaks may be associated with plumbing vents. This is a problem because the cause of the leak is often misunderstood. The vent itself does not leak water out onto the roof or into attic spaces. Instead, the leak is caused by improper installation methods around the vent pipe when it exits the roof. The vent itself may be working, but its attachment may need to be re-sealed.

References

• Check This House: House Plumbing Vent, Sewer and Drain
• Brady Home Inspection: Waste System Venting