Condo apartment plumbing systems rely on shared “stacks” that carry wastewater and sewage from condo units to the main sewer line. With hundreds of residents flushing waste down these systems several times a day, stacks present a high risk for blockage and unit backups. Here we look at stack risks and how your condo board can keep things moving with regular stack cleaning.

What Causes Stack Blockages?

Residents flush a wide variety of food and personal hygiene product waste down kitchen drains and toilets including cooking fats, oils, and grease as well as oils found in creams, cosmetics, soaps, lotions, etc. As softened oils, grease and fat enter the stack, they cool and harden, sticking to the pipes and plugging the system.

Underlying Stack Issues

Although your condo might not experience a backup, the buildup of greasy materials on the inner walls of the pipes are highly corrosive. Because a clog is inevitable, 20 years down the road when a clog does occur, the pressure of the stack cleaning will burst corroded pipes requiring costly unit repairs and stack replacement.

Understanding the Typical System

All unit drains in the building are connected to the main plumbing stack which runs vertically to the ground. Here, it connects to horizontal lines that carry waste to the city sewer.

A high-rise building of 20 stories tends to stick to a single stack cleanout required by plumbing code for stack access and cleaning. This is typically installed at the bottom of the stack in the lower garage level or basement near the lower stack. Also known as the “auxiliary” stack, this is the second portion of the system. It is a narrower portion of pipe used to service the bottom floors making it a common area for clogs.

Ideally, cleanouts should be installed where the auxiliary begins on the lower floors and then upwards throughout the building every five floors/ 50 feet. This improves stack cleaning efficiency, while reducing the risk of drainage backups and lower unit damage.

Efficiency in Stack Cleaning

Having a cleanout at the top of the auxiliary stack allows for easier cleaning from above to clear lower clogs right through to the main building sewer. However, while access at the bottom of the stack allows water to flow properly where the system becomes horizontal, any clogs in the area of the vertical stack above will fall downstream, reclogging the cleared lower stack.

A better approach is clearing both the horizontal and vertical sections with access through multiple vertical cleanouts to flush out the entire pipe system.

Flushing versus Chemical Cleaning

Annual high-pressure flushing is the most efficient way to clear stacks and reduce the risk of burst pipes. Reactive flushing to clear backups in older buildings increases the risk of burst pipes due to grease corrosion.

Although chemicals can help reduce grease buildup, the mix of chemicals and water dilute the solution’s effectiveness. It can also create further clogging by loosening debris still clinging to pipe walls. After the cleaning, the debris will fall into the system and become trapped at the elbows where the horizontal runs begin, creating a new clog. Therefore, efficient high-pressure cleaning is a much more cost-effective solution.

Enhanced cleanout installations in hand with preventative annual kitchen stack cleaning will help mitigate the risks of drainage system backups. Although cleanout installation does require knocking out a small section of drywall in some units, the long-term benefits outweigh the cost and inconvenience.

The condo experts at CPO Management Inc, a full-service property management company in Toronto and the GTA, have successfully implemented effective preventative maintenance strategies for residential high-rise condominiums. Reach out to us today to learn more about how we can help you realize substantial cost and time savings with our condo services.