Bathroom plumbing reconfiguration

[MC]

I am looking at installing a tub in the location of a current bathroom vanity.  The tub will fit in the footprint of the vanity, but the location of the drain and water supply will change.  Anyone have any good resources to research on how to do this work?

[zataks]

I typed a reply yesterday but didn't submit thinking other would have better responses; since there are none, I'll see if I can help.

I don't have any good resources, per se, but if you have questions, feel free to post them and I can help out.  I'm a tradesman in essentially large-scale plumbing but have done enough small stuff (home repairs and irrigation systems for work and home) that I hopefully can add some insight.

Basically, your influent (feed/supply) water lines are easy.  You can do just about whatever you want with them because they are under pressure (minimum 20psi at your meter if you're on a community water system in the US).  To do this work you'll need to identify what kind of materials the plumbing is made out of and how accessible everything is.  From there we can make greater determinations on what needs to be done. 
The drain/waste plumbing is a bit trickier because it must be at a constant slope (with few exceptions; for pretty much all applications, there much be a slope!); I think the industry standard is 1/4" of vertical drop every one linear foot.  If a little steeper, it shouldn't be a problem.  Much less than that though, and you could run into issues.  Not guaranteed problems but rather not risk these things.
Also, I believe you will need a vent line coming from your waste plumbing but if you're only moving the drain a couple feet and not ripping out much existing plumbing, the current vent should be adequate. 

If you've never done any plumbing work or handiwork in general, this may be a difficult task.  Not insurmountable as the concepts are basic; plumbing is simple. 

Post up any questions, status updates, pics, whatevers and I'll help where I can.
 

[Goldielocks]

Depending on where your vanity drain connects, the tub drain is larger, so you need to connect it to the main branch or stack, which may be a few feet away in the floor below or in the wall.

[MC]

Thanks both for the replies.  We're actually moving into this house in a few weeks, so I'll update this thread when I can provide actual dimensions of the changes.

[Cromacster]

I am not a plumber nor have I done anything of this magnitude in regards to plumbing.....but I have looked into it a touch.  The main concerns you are going to encounter are the drain and the stack.  There are codes for the slope of the drain to the stack and also how far away that drain can be from the stack.

These codes are why when you read about bathroom remodels or kitchen remodels they will typically say not to move locations...unless you want to make it a much bigger project.

This may not be the case in your situation, but something to keep in mind.

[Milspecstache]

If you are willing to raise the tub a bit you can compensate for the potential 1/4" per foot altitude problem.  I did this to go with a cheaper jacuzzi than the one I poured the slab for.  By raising the tub 3" I was able to use a $300 (new) craigslist tub vice buying a new $1200 tub.

I do still need to build a step to make getting in/out easier.

[Milspecstache]

I am not a plumber nor have I done anything of this magnitude in regards to plumbing.....but I have looked into it a touch.  The main concerns you are going to encounter are the drain and the stack.  There are codes for the slope of the drain to the stack and also how far away that drain can be from the stack.

These codes are why when you read about bathroom remodels or kitchen remodels they will typically say not to move locations...unless you want to make it a much bigger project.

This may not be the case in your situation, but something to keep in mind.

For the vent my local code wanted me to use the auto-vent devices which can be easily hid in the walls behind a mirror.  They only wanted one vent going up to the roof with no crazy tie-in's to combine them (per my submitted plan).  I think the reasoning was that sometimes those crazy tie-in's will clog causing problems.