Cast Iron Plumbing Stack
"A cast iron plumbing stack is a thing of beauty, especially if it's the sleek newer no-hub cast iron." Tim Carter - Founder, AsktheBuilder.com
This article was featured as "The Week Of Cast Iron" in Tim's opens in a new windowMarch 10, 2019 AsktheBuilder Newsletter.
Cast Iron Plumbing Stack - Quiet and Strong
Cast iron plumbing is still available and it's better than ever. The wall thickness of a cast iron plumbing stack is now consistent with modern spun-casting manufacturing methods.
You can have a plumber install a cast iron plumbing stack in your home. Here are a few benefits:
- cast iron is quiet - you'll not hear water rushing down a wall or across a ceiling
- cast iron is fireproof - PVC creates a toxic deadly gas when it burns
- cast iron is immune from leaks caused by errant carpentry nails
How Are the Joints Sealed?
Modern no-hub cast iron relies on ingenious no-hub couplings that combine a durable rubber collar with a full-size stainless-steel band clamp. When the two bolts on the band clamp are tightened to around 60 pounds of torque, they squeeze the rubber against the outer walls of the cast iron creating a water and gas leak-proof joint.
Watch this video to see these no-hub clamps:
How is Cast Iron Supported?
Vertical cast iron plumbing stacks transfer the weight to the floor using a simple riser clamp. The clamp tightens around the pipe and the strong metal legs spread out the weight onto the nearby floor.
Horizontal runs of cast iron pipe are supported by clevis hangers that cradle the pipe. A threaded rod with washers and nuts on each end are used to connect the hangers to the ceiling above.
You can also rest cast iron pipe on strong wood blocking if it runs through floor trusses as you see in this photo:
How Do You Cut Cast Iron?
I cut cast iron pipe using an electric cutoff saw equipped with a special carbide blade.
Is Cast Iron Expensive?
Cast iron is more expensive than the modern foam-core PVC pipe. It's important to realize you don't have to install cast iron throughout your home. Each vertical cast iron plumbing stack that has toilet water in it can be cast iron as well as and horizontal 3-inch pipes in ceilings.
All other plumbing drain, waste, and vent lines can be PVC.
How Does PVC Connect to Cast Iron?
You use simple PVC no-hub adapters to transition between cast iron and PVC pipe.