Cast Iron Pipes vs PVC Pipe - Precision Foundation Service

Replacing Cast Iron Pipes with PVC

If your home was built before 1980, it’s likely you have cast iron pipes. In the 20th century, it was standard practice to use cast iron pipes for sewer needs because they are sturdy and can last well over 50 years in perfect conditions. A few examples of perfect conditions for cast iron pipes are no consistent moisture in the ground, no invading tree roots, and no ground movement of any kind. By these requirements alone the world isn’t perfect for cast iron pipes which places them at risk of corrosion.  

As cast iron corrodes it creates rust, (brown water, anyone?), and holes will develop that let other sewage contaminants into the local area leaching into the environment. (Think what you flush down the toilet leaks into your yard! Yuck!) If that isn’t enough, the leaking from damaged sewer pipes can create pockets of loose soil that weaken the ground under the foundation, compromising its integrity. Loose soil under a foundation can cause structural movement, damage, and failure which will result in a lot of expensive repairs. 

Now that you have determined you have cast iron pipes, why replace them with PVC and how do they do it? 

Why PVC?

PVC can do all the things cast iron cannot do. PVC is considered environmentally safe, so you can rest assured that nothing will harm the environment or your water supply. Its lifespan is 70 to 100 years so once you get them replaced you won’t have to worry about replacing them again. PVC is flexible, this is an important reason, especially for areas with ground movement and invasive tree roots. Cast iron pipes are not meant to be moved around. They are rigid so any movement can cause them to break or disconnect at joints. The flexibility of PVC allows for reasonable ground movement without compromising its structure and stability. PVC is a light material compared to cast iron, so it needs less manpower to install and move around which equates to more money in your pocket. 

How do they replace the pipes?

An inspector will come out and discuss your options with you, but there are 2 main ways of replacing your cast iron piping with PVC: Trenching and Under Slab.  

Trenching is the process of digging a narrow trench of the earth around your pipes through your property and floors in your home. Once they trench around your existing cast iron pipes, they will remove them and replace them with clean, environmentally safe PVC piping. This process can be a bit messy, and you may have to find other accommodations outside of your home until the job is complete. It is also the less expensive route as it is a more direct method of reaching the pipes. 

Under Slab is the more popular choice as all the digging will be done outside your home instead of through your floors. Like trenching, they dig the earth around your pipes on your property but instead of digging through your floors, they tunnel under your foundation slab to reach your pipes. Even though it is more expensive, most people opt for this route because it is less messy and inconvenient for the homeowner as they do not have to leave the house.  

Whatever route you may decide to take, inaction is the worst choice because potential small problems, which would be caught with a simple inspection, can become exceptionally large and expensive down the road. Get an inspection if you are having plumbing problems that won’t resolve with traditional remedies, or if symptoms such as discolored water, a thriving lawn without trying, or a squishy wet lawn that smell like a cow farm are showing themselves.  

The bottom line is: If you own an older home that has or may have cast iron pipes, you should get an inspection. You’ll be glad you did. Contact Precision Foundation Service today for a consultation on pipe replacement.

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