Installing Drain Pipe in Joists

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Old 01-27-09, 12:35 AM
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Installing Drain Pipe in Joists

Hey! I'm turning my bedroom into a luxury bathroom and I will be putting drywall on the lower level ceiling too (right below it). That means I have to install the new drain pipes for the new tub/shower/sink (toilet already there) in the joists.

But how??? After cutting all the holes in the joists, how would you get he 1-1/2" pipe in the holes? I can't see the pipe flexing enough to get it started. Is there a product that allows me to get it into the holes?

The only other idea I have is to just cut the drain into a million 16" segments and join them together between each and every joist.

Thanks in advance. -Tony17112acst
 
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Old 01-27-09, 03:11 AM
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Generally, plumbers will try to avoid long runs perpendicular to existing joists for the reason you note, there are also other considerations as well, for example maintaining a consistent pitch, running out of vertical space to maintain the required 2" clearance to the lower edge of joists on long runs, and routing venting, to name a few.

Common alternates in your situation include dropping down vertically to a basement and performing the horizontal runs there, or routing plumbing along the joist cavity to a wall and then horizontally along the wall below the joists in a small soffit, in either case you have to made sure you are venting properly.

If you do bore through joists make sure any holes are properly places and sized, I frequently observe misplaced holes and notches made to accommodate plumbing installed at homeowner renovations and remodels:

The rules for in solid sawn lumber (conventional joists) are simple:


- Ask Codeman.

Manufactured floor joists have their own set of rules; check the manufacturer’s installation instructions.
 
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Old 01-27-09, 11:03 AM
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I have that sketch but I love that you were concerned enough to post it. It should be in the sticky :-).

Anyway, I think I'm willing to cut the 12' run into 16" lengths an make it really slick.

#1.) What is the drop per foot I need for the tub and the shower drain (no sloids in there)?

#2.) Am I OK with code to join the whirlpool tub and shower with a 1-1/2" drain (they get seperate vents of course) and then that same drain will run 12' to the 3" main with another 1/2 bath sink connecting into that same drain run 12" before it drops into that 3" main drain?

To put it another way, the whirlpool tub and shower will be right next to each other, the two drains join there and runs 12 feet, then a 1/2 bath sink joins 12" before the 3"main drain pipe.

If so, this will solve all my drain issues as far as keeping them in the ceiling, since I want to drywall it below.

Thanks again! -Tony

Shwr Tub
|||| |__|__________________|--| <--sink
|_____|_____________________|_____====== 3" main
1-1/2" drain--^ (12' run)

(not bad for ASCI)
 
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Old 01-27-09, 09:15 PM
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Anyway, I think I'm willing to cut the 12' run into 16" lengths an make it really slick.
Are you really sure there's not another way? I hate cutting 1.5" holes in any size joists because of weakening the joists.

#1.) What is the drop per foot I need for the tub and the shower drain (no sloids in there)?
1/4" per foot is standard. 1/8" is the minimum by code, and I know there is a maximum, though I'm not sure what it is.

#2.) Am I OK with code to join the whirlpool tub and shower with a 1-1/2" drain
Nope. Your tub is good with 1.5" drain, but a shower requires a 2" drain. Both the tub and shower can drain into the same 2" drain. The sink could dump into this same 2" drain as you discussed.
 
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Old 01-27-09, 10:02 PM
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Thank you very, very much. I should have all the info now to proceed. I will drain the new sink into an existing sink drain and then run the tub/shower in a new 2" drain 12' to the 3" main drain.

I wish there was a better way, but I really can't do a drop ceiling in this already no-headroom lower level. I do hate to put 2+" holes in the joists too.

If there were a way to ram a 2" drain into a 3" copper drain (yes 3" COPPER), i do have another way. But the rubber "Y" is way too long that would allow me to tap into it where I need to. I'll try to brainstorm too.

Here's a photo of where the drain could enter the main 3" drain. As you can see it is lower than the ceiling and I could run it against the wall which I can put a wall in front of. This is copper, so I'd need something that would allow a 2" drain go into that section (or the elbow I guess). The white block wall is the exterior wall and this is where the drain enters the septic tank area.



Thanks again folks for your kind use of your time. -Tony
 

Last edited by tony17112acst; 01-27-09 at 10:40 PM.
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Old 01-28-09, 11:55 PM
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either you remove the 90 and replace with a tee or youll put it in the horizontal part and there are certain rules you must follow to instll it in the horizontal.

can you post a sketch or pic showing where these fixtures are in relation to each other, the walls and measurements of the room and of each fixture, and where the old plumbing under the bathroom is, what sizes and where they are
 
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Old 01-29-09, 09:31 AM
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One sketch coming up!

 
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Old 01-30-09, 11:50 AM
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well, hmmmmm, unless you can drop the drain for the tub and that other fixture down to the basement and tie it in there, the green line is the only viable solution , if installed properly with vents and such.

will all the existing fixtures will stay where they are, especially the toilets?
 
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