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Brian
Brian, Architect
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Experience:  Licensed Architect- 17 years
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I am installing a tub on a concrete slab in ...

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I am installing a fiberglass tub/shower on a concrete slab in garage, along with a lavy and toilet on the same wall. There is a 12'' run to my septic connection, which is 7" below the level of the top of my slab. With the 3" drop I need, this leaves me 4" to install the 3x4 reducing elbow to the toilet. Two feet further is the lavy and three feet from the lavy will be the tub. I have figured out the toilet installation (I think I have an inch to spare). How much room will it take to put the tub/trap in from the drain of the tub through the removed cement and to the drain. Also, I assume I will need to connect all 3 drains together at some point before the connection to the septic. I am framing a new wall to install the fixtures against and will have to cut into the concrete for my plumbing. ps - I also have a 2" thick, 4'' wide 4" deep "valley gutter" just outside the garage, which drains off water in heavy rain. I will need to cut into that, too. tp get to my connection.

HelloCustomer

Welcome to Just Answer.

Your question is long, but it sounds like you are simply asking if the tub drain will fit within the 4 inches you have to work with; please correct me if I am wrong. If this is the case, I believe that you can fit it; it is usually the toilet that is the hardest to fit due to the larger piping required. The diagram below, showing a cutaway view of a tub and drain will give you an idea of how the tub should be drained. Since there is a trap involved, the vertical distance from the tub drain to the end of the trap can be within the 4 inches, easily. The diagram shows the trap low, but you should install it higher.

graphic

 

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Customer: replied 9 years ago.
Thank you for the help. I guess I can figure out the diagram rearranging it to install the trap higher, so it sounds like the tub will not be a fit problem, if the fall to the septic connection will be ok (is it also 1/4" per foot like the toilet?). I still need to know how to go about connecting the tub drain and the lavy drain to the toilet drain within the space I described that I have. So far your answer has been very helpful. If I can understand the whole installation to have the confidence to go ahead, then certainly your service is well worth-while. If so and this turns out to be an example of your answers, they are a lifesaver and also worth more money. Thank you.

All drains should be vertical or pitched at 1/4" per foot.

I will respond back in a few minutes. I am going to scan a picture of a similar bathroom setup showing all of the plumbing, so that you can better understand how to connect everything. It is easier than trying to describe it with words, which would take several paragraphs.

This is an article that I was just browsing in Fine Home Building. It shows a basic layout and how the drainage components connect to each other. Ignore the sewage tank and pump in this picture; the drain line would keep going to your septic connection, in your case. Your fixtures can be located in different locations, but you can still use this picture and apply it to your layout. The vents are shown, as well, and these are typically inside of the bathroom walls. The vent pipes can become one and will need to vent thru the roof; getting to the roof can be done by travelling thru closets, etc. on the floors above.

graphic

 

 

If you need further help or clarification on this answer, please do not hesitate to reply to this post.

Thanks for asking your question at Just Answer.

Best of Luck, Brian

 

Please leave feedback at your convenience.

Customer: replied 9 years ago.
The drawing will be useful, I am sure. I will need to give it a bit of study and reverse it for my purposes, as the toilet is the last into the drain access to septic. I just need to figure out to get the tub and lavy drains to that toilet drain, still keeping the pitch, when I have only an inch or so to work with. I think it can be done. Thanks for the boost of confidence.

Your welcome.

Thank you very much for the accept and bonus.

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