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Mark Polman

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I have done quit a few DIY plumbing jobs over the years, so I know the basics, but for this one I could use some advise. I'm remodeling our bathroom which happens to be a galley bathroom, with vanity (sink) and toilet on the left and the shower and bath on the right. The current setup of the bathroom has the bathtub furthest from the door on the right with the shower immediately to your right as you walk in. My wife wants to switch the positions of these two, putting the shower where the bathtub is and the bathtub were the shower is. Currently, the drain for the bath takes a perpendicular path under the floor of the bathroom, and I'm assuming connects with the drain for the sink. The drain for the tub uses a 1.5 inch drain, and they've cut holes in the joists (2x10) to enable the bathtub drain to meet the drain for the sink. I'd like to abandon the old bath drain with runs perpendicular to the bathroom and just tie both the shower and the bath into the existing shower drain that runs parallel to the bathroom on the right side. Can I tie both the shower and the tub into the existing shower drain which is 2" abs with a wye or do I need a larger diameter pipe to carry both? I would still have my separate vent about a foot away from the new shower (in wall that separates shower and tub) and also a vent at the end of the drain line where it meets the drain pipe that runs down into the basement and out of the house. The vent at the end of the existing 2" drain would then be a foot or so from the new location of the bath tub. I'm not sure if both the tub and shower can both drain into the 2" drain pipe without issue. We would probably never use both at the same time, but I want to do it right. So, the new layout starting furthest from the door, would have the new shower, which would then have it's vent in the wall that separates the shower from the tub, the new tub, then just past the tub, the separate shower and tub drain pipes would connect into the same 2" drain pipe using a wye, which then runs another few feet before it meets up with the larger drain pipe which carries the water down and out. There is also a vent at this junction which serves the current shower.
 
Post many pics of your current bath.

Then draw a diagram showing current fixture locations, vents, drains.

Then draw a diagram showing desired fixture locations.

Someone on here will fill in the plumbing changes for you, I expect.
 
Thanks frodo and Jeff for the responses. I've attached some pics that I mocked up of my current layout and what I have in my head for the new layout. I appreciate the advise! Also, if I can tie the 1.5 bathtub drain into the 2" shower drain using a wye, where should I increase the 1.5 to 2, before the P-trap or after? Unless there is a wye that splits into both a 1.5" and 2"? I didn't see one at my local DIY box store.
 

Attachments

  • Current Bathroom.PNG
    Current Bathroom.PNG
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OP.SOCBfXlbHDkY3Q474C474


you use a 2 x 1 1/2'' bushing on top of a 2'' ptrap for the tub
 
Thanks frodo. Can I plug the old 1 1/2 abs bath drain anywhere along its branch? My thought was to plug it just after the current location where the vent branches vertically from the drain pipe since I will be moving that vent to it's new location in the new wall that will separate the new shower and bath location?
 

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