# plumbing rough-in for a concrete slab



## JennP (Aug 31, 2012)

Hi there,
I am going to build a 14x16 foot studio on my property. I want to build the entire project on my own, this is exciting, but also daunting! 
The site has been excavated and now has three inches of gravel on it.

My question is in regards to the plumbing rough-in. The space will have a toilet, bathroom sink, shower, kitchen sink, and a floor drain for hot water tank.
I'm struggling with the rough-in layout for these drains. I can't figure out how to lay out the venting for these fixtures. Is one vent enough? And where should the vent be placed? Can I tie in the sink drains after the toilet without concern of the toilet backing up into those drains?
I read somewhere that that a wet vent should not be downstream from the toilet. This has me confused. 
Does anyone have any thoughts, or web sites they can recommend.
Thanks very much!


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## DannyT (Mar 23, 2011)

which side is the sewer connection on?

where is the water heater going?

is this going to be on a slab or raised with a crawl space?

the bathroom can be vented with one and the kitchen needs one also.

depends on where you need the floor drain. why do you need a floor drain for the water heater?


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## JennP (Aug 31, 2012)

Hi Danny,
Sorry but I wasn't able to add that information to the drawing.

The sewer connection is on the left side of the plan to the left of the "couch". I'll call that the N.E. side of the house.

The plan shows the kitchen sink in the S.W. corner on the house but it will actually be closer to the S.E. corner. The water heater is going in the S.W. corner. I want to put a drain for the hot water tank so that if it blows out the water will go down a drain rather than all over the house. Also, I am considering a small washer in that corner and having a drain there would give me some options (I would tee off the drain and stub in the wall for this option later).

When you say that the bathroom and kitchen each need a vent does that mean two vents through the roof, or can I tie the two together and have only one going out the roof?

Thanks for taking the time to look at this!


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## JennP (Aug 31, 2012)

I should also say that I am not doing this project with a permit, and so local code requirements are not a factor. 
Thanks,
Jenn


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## ben's plumbing (Oct 6, 2011)

JennP said:


> I should also say that I am not doing this project with a permit, and so local code requirements are not a factor.
> Thanks,
> Jenn


 say what....no permit...no inspections...do you really want to do that????this could come back and bite you....


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## joecaption (Nov 30, 2011)

I would never suggest a DIY do all there own rough in plumbing, and in a slab even more so.
This is a one shot deal.
Also forming and poring the slab is not a DIY project.
It's one thing to want to save money but to end up with a plumbing system that does not work or is not up to code is not going to save anything.


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## oh'mike (Sep 18, 2009)

ben's plumbing said:


> say what....no permit...no inspections...do you really want to do that????this could come back and bite you....



There are a surprising number of places that require NO permits for out building---especially if the zoning is 'agricultural'

All the more important that we help this member avoid mistakes.

To the OP--can you post a sketch on the site? My computer doesn't like PDF files.


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## TheEplumber (Jul 20, 2010)

JennP said:


> I should also say that I am not doing this project with a permit, and so local code requirements are not a factor.
> Thanks,
> Jenn


permit or not- codes are a factor.
People don't just sit around and dream up standards so they can watch builders jump through hoops.
You better study those standards- or better yet, hire it out


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## oh'mike (Sep 18, 2009)

TheEplumber said:


> permit or not- codes are a factor.
> People don't just sit around and dream up standards so they can watch builders jump through hoops.
> You better study those standards- or better yet, hire it out


Good catch---absolutely follow code---under a slab is no place for mistakes.


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## ben's plumbing (Oct 6, 2011)

that is what I am saying....to important not to follow some sort of standard found in permits.codes, which will be revealed in inspections....yes...:yes:


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## Alan (Apr 12, 2006)

The bathroom is not wide enough.... you have a toilet crammed next to a neo-angle shower which I will assume is a 36" (anything smaller than that and neo-angle is going to be uber-useless), and the overall measurement of the bathroom is 5'6" from center of 2x4 wall to outside of (assume 2x4 wall)... That leaves you with only 5' and 3/4" inside of room. You need 30" from FINISHED wall on either side of the toilet, and that only leaves you... 30-3/4" for the shower. 


This is not good.


I could draw you a plumbing diagram, but I don't know what your location is, and it may not meet code (yes, meeting code is important whether or not you are having inspections.

An exact location where the sewer is going to enter the building would be helpful as opposed to "by the couch" 

Lastly, how comfortable are you with plumbing? This is a one shot deal in a slab, if you mess it up, and it doesn't work, you have only one option. :wink:


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## JennP (Aug 31, 2012)

Oops, duplicated this so deleting one.


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## JennP (Aug 31, 2012)

Hi there,
Yes, I agree that code requirements are in place for good reason( mostly).
And yes, I do live in an area where I'm not required to have a permit for this little building.
I have considered consulting with a plumber, and may find that I have to, but am hoping that if I do enough research, and engage with a DIY site like this one for guidance, that I can figure this out and do it myself.
As I'm sure that most people that attend a DIY site and forum will understand, there is a great sense of accomplishment in creating something or fixing something yourself. And of course the cost savings as well. That is part of the attraction of doing this building myself, to learn as I go, and create something unique, creative, and practical, that I can be proud of.
Of course there are some things that I wouldn't touch, such as the actual pouring and finishing of the slab, and the electrical too, but I think I'm up for doing the rest myself.
I'm not in a hurry so I can take the time to make sure that I've got it right before moving forward.
After i get the plumbing sorted out i will lay rigid insulation, and then pex for in floor heating. After the pour I want to rent a grinder and grind down the cement to a smooth finish. I'm told that I can "seed" the cement, when it's being poured, with specific aggregates that will customize the look of the floor. I'm thinking that beach glass may look interesting. But anyway, back to the plumbing...


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## JennP (Aug 31, 2012)

Hi Alan,

Yes I agree that the room is very small for a fiberglass shower base.My friend drew up this little plan for me and I had the same thoughts as you. So my intention is to prepare the slab with a 1 1/2 or 2 inch deep( haven't decided which yet) 2x2 foot wide recess in the shower corner of the bathroom. I will put the shower floor drain in this recess.This recess in the cement will accommodate a teak grate that will lay into it, but be flush with the floor. This is fairly common in Europe where they often have tiny bathrooms.

I live in BC Canada, on the coast. The climate is mild here on the water and so freezing isn't a factor.

The exsisting septic tank is about 40 feet from the upper left side of the cabin plan, so even though"by the couch" is a lame discription it's the best I can do until I find a way to modify the drawing with information.

I am comfortable enough with plumbing to be able do this project.

Thanks for your feedback, I appreciate it!


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## Alan (Apr 12, 2006)

So with the tank 40 feet away, the pipe can come in anywhere in the general vicinity of the couch is what you're saying. :yes:

You do realize even with a concrete floor you will still need to protect the floor with a proper shower liner system? If you do not, the oils and soap scums that you rinse off of your body will absorb into the concrete and make it stink. You need to figure your recess of the shower based on the size of the shower, as the sub base of the shower will need to be sloped so that the liner will be sloped, as well as the finished surface all 1/4" per foot. The overall thickness of the drain you get will make a big impact on the depth.... 2" does not sound like enough to me.


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## JennP (Aug 31, 2012)

DannyT said:


> which side is the sewer connection on?
> 
> where is the water heater going?
> 
> ...


Just figured out how to use the "quote " button.
Hi Danny,
The heater is going in the bottom right hand corner of the plan( I know, I need to improve the drawing but don't have the technology yet). The heater will be for in in floor heating. I would like a drain in that corner in case the hot water tank blows. Also, it's a code requirement here . I would also like to tie into that drain and run a pipe in the wall in case I want to install a little washing machine in that corner.

This is a slab, so of course it's VERY important that I plan this well!
Thanks for your input!


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## JennP (Aug 31, 2012)

Alan said:


> You do realize even with a concrete floor you will still need to protect the floor with a proper shower liner system? If you do not, the oils and soap scums that you rinse off of your body will absorb into the concrete and make it stink. You need to figure your recess of the shower based on the size of the shower, as the sub base of the shower will need to be sloped so that the liner will be sloped, as well as the finished surface all 1/4" per foot. The overall thickness of the drain you get will make a big impact on the depth.... 2" does not sound like enough to me.


I didn't know I would need a liner for this. Couldn't I just seal the cement with something to make it impervious rather than a full on liner? It could be tricky finding a liner to suit, and custom made would be costly.


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## Alan (Apr 12, 2006)

JennP said:


> I didn't know I would need a liner for this. Couldn't I just seal the cement with something to make it impervious rather than a full on liner? It could be tricky finding a liner to suit, and custom made would be costly.


If you're not using a fiberglass pan, then you need to "Make one" using approved methods and materials read : (custom). Those are your options. If you opt out of using any kind of a pan system, do expect that the concrete will absorb all of that crud and become very smelly. Concrete is very porous and I assume that even with the best sealing methods, water will find a way into the concrete anyway.

I saw your post about a floor drain in case the heater blows : Using a floor drain is fine, but with a floor drain you'll want a trap primer to keep the trap from drying out and stinking up the house. Your other option would be to put the water heater in a pan, and plumb a drain from the pan out of the building above grade. This will be much cheaper, and will work just as well, assuming the heater is going on an outside wall.

I made a quick sketch of the way I would plumb it (attached). Not sure if it meets code in your area or not... I figure the sewer entering the building about 2-1/2 to 3 feet from the corner of the building under the sliding glass door.


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## JennP (Aug 31, 2012)

Thanks Alan,
It seems like I will have to sort out a liner for this shower. Happy to find this out now rather than later with a stinky bathroom!

Running the hot water tank drain outside the slab is a good idea, i will do that. And as far as having a drain for a washing machine goes, I don't think I really need a drain because the small kind of washer that will fit in this place could be the type that just hooks up to the kitchen sink. 

I'm finding the plumbing sketch hard to read. It's not clear to me where the drains tie into the system, particularily in relation to the toilet.


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## oh'mike (Sep 18, 2009)

To waterproof the concrete----there are many ways---if you tile it--use a paint on waterproofing like Hydroban by Latacrete or one of the other good brands----


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## RocketGal (Mar 29, 2012)

*Open a pdf file*

To oh mike and others who need to open a .pdf file occasionally: http://get.adobe.com/reader/ at this site you can download free software that you can install on your computer so you can automatically open and read .pdf files. Adobe Reader is what you need. (Click no to refuse any add ons that you don't want.)


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## JennP (Aug 31, 2012)

oh'mike said:


> To waterproof the concrete----there are many ways---if you tile it--use a paint on waterproofing like Hydroban by Latacrete or one of the other good brands----


I just watched a 10 min youtube vid on the Hydroban and it looks as though that will work for me. Thanks oh'mike for the info!


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## dukeoftheozarks (2 mo ago)

DannyT said:


> which side is the sewer connection on? right where is the water heater going? by garage is this going to be on a slab or raised with a crawl space? slab the bathroom can be vented with one and the kitchen needs one also. depends on where you need the floor drain. why do you need a floor drain for the water heater? condensation, als mud room


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