Tub to Shower Drain

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  #1  
Old 10-27-08, 10:05 PM
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Tub to Shower Drain

Just starting a remodel of master bath in manufactured home. Bath has both a shower and a garden tub. Have removed garden tub and will be replacing with 48 x 48 shower. Plan on using Kerdi kit. After removing garden tub I find the P trap below existing floor level but as luck would have it, it is a 1 1/2 inch drain and not a 2 inch as required by code. I dropped a camera into the cutout around the P trap and took some pics, hoping to find how far it went. Goes at least 8 feet and I suspect it ties into main drain or into existing shower drain but couldn't see that far. Before I crawl under and see what I have, I have a couple of questions. If the 1 1/2 inch drain ties into the main drain, what is the usual size of the main drain and are most secondary drains y'd into the main? This unit was built in 1990 and I suspect that the existing smaller shower in the master bath has a 2 inch drain as it should be according to code. I would like to replace the 1 1/2 inch drain with a 2 inch drain but realize that this may not be possible without calling in a plumbing company. I will not be pulling a permit for this remodel. I also will not be putting in more than one normal shower head in the new shower. I understand that no one is going to recommend that I leave the existing 1 1/2 drain as is but it would be very simple to connect the new shower drain to it. The garden tub that I removed also had a hidden studor valve that I will be replacing with a stack through the roof. This will be a 1 1/2 inch stack unless others recommend something different. Thanks in advance for any responses and I am sure that I will be back with more questions as this project proceeds.
 
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  #2  
Old 10-31-08, 08:19 PM
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Location: Volusia County, Florida (Central)
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You should use 2" drain to shower, washing machine, and tub..1 1/2" for sinks. Vents should be 2".

Vents should be no more than 5' from the drains...



Doing the drain is something I would try myself,,,,(and have).... just make sure you have 1/4" slope toward the main waist pipe......you would place a Y with a short piece on the end at the connection to the main drain and a rubber coupler so you can insert it in between the existing main. Really quite easy.....

Good Luck
 
  #3  
Old 11-01-08, 07:44 AM
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Barlow46 - The question has been asked several times here. No one has been able to adequately explain why a shower needs a 2" drain per current code when 1 1/2" shower drains worked fine for years.

When I redid my master bath I found that removing and replacing the 1 1/2" drains would have been a huge PITA adding cost and time to the reno. I ended up using a stub 2" mated to the existing drain that stuck up through the subfloor just to pass rough in inspection. We use this shower daily and have never had any drain problems.

Maybe there are some plumbers in the forum that know why a 2" drain is required.

My washer drain also has a 1 1/2" drain (as built). We've been using it for 25 years w/o a problem but if I decide to move it, code requires that I replace the drain. Makes no sense to me.
 
  #4  
Old 11-02-08, 08:43 PM
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Thanks for the reply. It was explained to me that the code has to do with the idea that a tub can hold more water than a shower stall should a drain become stopped up and thus lessen the chance for an overflow should someone step out of the bathroom with the water running. Also, I guess that more people today are putting multiple shower heads in their showers and the drain needs to be larger to handle the water. I don't plan on doing that; just one standard shower head. It is hard to justify quite a bit of extra hard work and expense to make the change but I usually find that codes are there for a reason and I try to remember that they are "minimum" and not "maximum". I will continue to look into it after I get someone younger and skinnier than me underneath.
 
  #5  
Old 11-03-08, 03:58 PM
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I thought the tub drain was supposed to be 1 1/2". Why are all the tub/overflow kits 1 1/2"?
 
  #6  
Old 11-04-08, 07:52 AM
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Originally Posted by MikeVila View Post
I thought the tub drain was supposed to be 1 1/2". Why are all the tub/overflow kits 1 1/2"?
Tub drains may be 1 1/2" but current code requires that shower drains be 2".
 
  #7  
Old 11-17-08, 09:06 PM
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Another idea. I am removing an existing vanity cabinet with two sinks and two separate drains for the sinks. I am replacing only one sink. One of the sink drains is about 6 feet from where the new shower drain will be located. I can get to the drain easily. I also have the existing tub drain which is very close to where the new shower drain will be. Can I put in a 2 inch fitting from a schluter kerdi drain kit and either T or Y to both drains, effectively giving me a 3 inch total drain. Or, have I created some other problems. The sink drain has a studor valve and the new shower/tub drain will have a
2 inch vent stack through the roof. If this will work, I won't have to tear out any underbelly and rework the existing tub drain.
 
  #8  
Old 12-02-08, 04:31 PM
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See last post. Still wondering if I can connect one 2" shower drain into two 1 1/2" separate bath and sink drain? Both are within easy reach (4') of new 2" shower drain. Also, could I vent the sink drain with a studor vent and the existing tub drain with a 2" stack through the roof? Thanks
 
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