ACCEPTABLE SIZE FOR A BATHROOM SINK DRAIN PIPE

Help Support House Repair Talk:

dsteinhorn

Member
Joined
Dec 31, 2017
Messages
13
Reaction score
1
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

Supporting Member
Supporting Member
Joined
Sep 30, 2006
Messages
4,446
Reaction score
944
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

Well-Known Member
Joined
Nov 19, 2007
Messages
3,131
Reaction score
354
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

Well-Known Member
Joined
Jan 3, 2017
Messages
296
Reaction score
97
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

Member
Joined
Dec 31, 2017
Messages
13
Reaction score
1
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

Well-Known Member
Joined
Jan 3, 2017
Messages
296
Reaction score
97
they have it at real plumbing store . or can order it .
 

Latest posts

Top