Cast Out The Cast Iron: Converting Old Plumbing Stacks to PVC

by | Right Bath by Mosby

KWare-932-ColorWeb Our Right Bath Division Manager gives some insights on when an old cast iron stack should be replaced and why. “Replacing an old cast iron stack is important to avoid future leaks, backups and clogs from old worn down existing plumbing.”  Ken explains.

What is a plumbing stack?

The plumbing throughout a home is connected to a main plumbing stack that runs from the lowest level of the home and often times vents through the roof. The purpose of the stack is to remove sewage and to prevent sewage gases from seeping back into the home; this is stopped by traps, or curved sections of pipe that seal off the gases.


Why PVC?

stack xsectionStack replacements can be done on homes that are one or two stories and most of the time the stack will be replaced from the basement floor up through the roof. Switching to PVC allows for easier changes in the future as it works with new plumbing fixtures more cohesively.  For this type of work a plumbing permit is needed to ensure the job is being done correctly and up to code.  At Right Bath we always pull the necessary permits to protect the homeowner and to ensure the work is done up to local municipality requirements. PVC is a flexible, rust resistant and durable alternative, so converting to PVC really modernizes the plumbing system within the home, making it a solid, more reliable choice. Not only does it ensure further peace of mind for the homeowner but it’s a great selling point for a home on the market. According to, a project like updating an indoor system, such as plumbing, is a top home improvement project you can do to increase your property value. For more information on that, you can visit here.

When is it time to replace your stack?

cast iron pipeBesides just replacing the stack for preventative measures there are more immediate tell-tale signs that a stack should be replaced. For one if the stack has barnacles, in other terms, scab like rust spots, it could be a sign that the stack is starting to rot from the inside out and become brittle.  Small pinholes in the stack can eventually lead to larger pinholes and possible leaks.  If this is the case, the stack would need to be replaced. Any stack that has been banded is a sign that there was an issue at one point. Banding is a temporary patch solution, and it should be addressed sooner than later. A stack that has a joint that is leaking will certainly need to be replaced, this leaking could lead to bacteria and potentially unhealthy and harmful waste seeping out.  This is something a homeowner should take care of right away.

If two bathrooms are connected to the stack it is better for both sinks and toilets to be connected to the new stack, and if a bath tub is to be converted to a shower, the drain size needs to be increased from 1 1/2 ‘’ to 2’’ pipe. These are common changes during bathroom remodels and something we take care of all the time for clients.

It’s important to choose a licensed and insured contractor when doing your bathroom remodel or plumbing work to make sure their work is up to industry standards and code requirements. Right Bath is a one-week bathroom remodel that will solve your bathroom and plumbing needs. All work is code compliant, down to the studs and will not cover up any existing issues. Right Bath will get you the look you desire with quality products from Kohler, Onyx Collection, Wellborn Cabinet and more. To schedule an appointment for a free consultation, you can give us a call at 314-909-1820 or go 

Why Work with Mosby Building Arts?

If efficiency, knowledge and quality craftsmanship are of the utmost importance, then Mosby is the partner for you. We are a design build firm that handles every aspect of your remodeling project from beginning to end. All team members needed to complete your project (designers, architects and production crews) are under one roof to provide time and monetary efficiencies, quality control, and seamless communication throughout.

Custom Bathroom Remodeling

Start your bathroom remodeling project with Mosby’s certified designers and architects. They begin the design process by learning about your exact needs and desires. Be it a hall bathroom, a master bathroom or an accessible bathroom, our designers will make sure it looks the way you desire and performs above and beyond your expectations.

Learn more about custom bathroom remodeling here.

Semi-Custom Bathroom Remodeling

A semi-custom bathroom remodel from Mosby is ideal for those with a standard sized bathroom that needs remodeling but does not require extensive changes to the footprint of the space. Our process is streamlined for maximum efficiency, which means a beautiful new bathroom could be yours in just 1-2 weeks.

Learn more about semi-custom bathroom remodeling here.

Home Remodeling Peace of Mind

There’s no need to deal with multiple companies, or the frustration of the left hand unaware of what the right hand is doing. Mosby takes the guesswork out of home remodeling by planning the work and working the plan. You will know the scope of work and price before the first hammer swings. And the work will be done with a commitment to excellence and your happiness. All of Mosby’s remodeling work is backed by our 10-year workmanship warranty.

You can trust you’re in good hands with Mosby:

  • 10-Year Workmanship Warranty
  • 70+ Years Experience