I am going to be cutting into a 4" stack pipe to add a 2" T that feeds a new shower/sink. About a foot above where that T will go is where the toilet line meets the stack. Do I need to support the vertical stack with a riser clamp or can I just support the horizontal line from the toilet with a long 2x4?

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Originally Posted by ianfeldberg

I am going to be cutting into a 4" stack pipe to add a 2" T that feeds a new shower/sink. About a foot above where that T will go is where the toilet line meets the stack. Do I need to support the vertical stack with a riser clamp or can I just support the horizontal line from the toilet with a long 2x4?

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This would be putting weight on the branch of the fitting causing undue strain on the joint. Better be safe then have the cast iron come crashing down. Use a raiser clamp on trhe vertical section of the stack. Good luck, Tom