ACCEPTABLE SIZE FOR A BATHROOM SINK DRAIN PIPE

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dsteinhorn

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Due to space limitations and needing to cross a joist near its end, I want to use a 1-1/4" ABS drain pipe for a simple bathroom sink drain pipe. There is no toilet or shower connected to this drain. I know that 1-1/2" ABS is typically used. Because there will be no solids like from a kitchen sink, is there any reason that 1-1/4" is not acceptable for this application? I want to take out as little of the joist as possible and recognize that piercing it near the end minimizes the loss of structural integrity.
Thanks for your thoughts.
 

Snoonyb

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The 1st 12" of a framing member are not recommended for penetration, so you should drill in the center 1/3rd of the width of the member, more than 12" from the end.
 

kok328

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Could you scab on some 2x10 maybe 4' long, on each side of the joist prior to drilling through it to give some strength.
 

billshack

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1 1/4 pipe for a lavatory sink is fine according to the plumbing code. the reason we use 1 1/2 pipe is that it is cheaper.
 

dsteinhorn

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1 1/4 pipe for a lavatory sink is fine according to the plumbing code. the reason we use 1 1/2 pipe is that it is cheaper.
I am having trouble finding 1-1/4" ABS here. Can I use use rubber "no hub" connectors 1-1/2" to 1-1/4" and splice in a piece of1 1-1/4" PVC? I know it's like Rube Goldberg, but structurally it should be sufficient.
 

billshack

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they have it at real plumbing store . or can order it .
 
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