Re: Remodeling bathrooms - drain and vent question (Updated drawing)
Posted by Ed on June 18, 2003 at 16:15:14:
In response to Re: Remodeling bathrooms - drain and vent question (Updated drawing)

Hi Brian,

I am in the process of remodeling our basement. Included is a full bath.

This board is a WONDERFUL Forum of info.

I am not a licensed plumber, I have done extensive research into the subject. Including code requirements. I am NOT an expert. However I thought I might be able to help a bit.

First off, you will want to ensure that your diagram is code-acceptable. There's some areas where you may be close to the fence.

#1 As Deb indicated the maximum distance from vent to lav trap(1.5") is 42". That's correct. For 2" drain like bathtubs (in your drawing) the distance is 60". You'll want to check your measurement in that (revised) drawing to make sure
you're within that 60" critical distance.(Tub traps to vent line - that's 60" for each not for both)

#2 You show a 2 inch drain flowing with two tubs and two lavs. Horizontal and Vertical 2" emptying into a 4 inch sewer. Maximum fixture units for "horizontal" drain is 6. Two tubs = 4 FU. For vertical drains it's 10FU. 2 Tubs and 2 Lavs = 6 going to vertical.

This should work.

You do not show any water closets. I am assuming they are on separate drain lines - that 4" stack by the tubs and they are also within the critical distance. (72" each for three inch drains)


#3. You show a sanitary T draining the tubs to the vertical drain. Keep in mind that whether you
use a T or a Wye - to help with proper drain flow you may need to add an elbow. For example: Waste T or Wye with a 22.5 or 45 degree elbow. The idea is to get a "sweeping flow" with no "tight angles". Depends on how you place the fittings.

#4. Also mentioned in another post - you can not have a double P - trap. It's contrary to code! For example, I read in an unrelated post on this board that someone wanted to trap a toilet. This would result in the toilet not flushing because a toilet already has an internal trap within. It just does not work that way. Could you imagine having to clean a toilet with two clogged traps???!!!


Hope this helps you.


: Hi Terry,

: Thanks so much for your reply. I've made a new drawing which I believe shows the changes you suggested. Can you take a look and let me know if it looks better.

: One of my concerns was that the 2" drain might not be a big enough pipe to drain all 4 fixtures. Is the 2" OK, or should I use a 3" pipe from the sewer to the lavatory double fixture fitting?

: I really appreciate the help.
: Thanks again,
: Brian

: : Brian,
: : the best way, if you are putting both tubs on the same line, would be a double fixture fitting instead of the tee fitting, with each tub having it's own trap arm and p-trap.
: : The vent from the fixture fitting (tubs) would tie in to the vent line above the lavs.
: : This way, you would keep the 2" line to the lavs (fixture cross), and use 1.5" trap arms for them.
: : Where the waste line ties into the main line, you would use a wye or combo fitting.
: : A sanitary tee on it's back will not work there.
: :

: :
: : Do not plumb it this way.




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