ACCEPTABLE SIZE FOR A BATHROOM SINK DRAIN PIPE

[dsteinhorn]

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]

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.

 

[user 4883]

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]

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]

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]

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