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ferris13 09-25-2009 01:21 PM

Basement bathroom rough in plumbing
I am considering doing the work myself but had a few planning questions. I was quoted 500-700 to do the rough in (take up concrete, tie into sewer line, rough in shower and toilet drains). I would be just replacing the cement myself.

Anyone have any pictures of how to tie into the sewer line?

I bought the Black and Decker Guide to Plumbing which has a nice layout but of course it is the perfect scenario. I am concerned that my sewer line is going to run at a 45 degree through my proposed bathroom location. Which I guess isn't bad, just maybe more concrete to remove instead of a straight shot if it was running parallel to a wall.

Other issue I see is that most people have existing rough ins and vents roughed in. I don't have that. Next question would be how to vent a (toilet, shower, urinal, and two sinks (lav sink and adjoining bar sink). I spoke with a contractor and they seem to indicate I could use the existing stack (3" that is the drain for my kitchen and 2nd floor bathrooms (2)) to vent the toilet and shower but I would need Studors on the other fixtures.

btw - I have to stacks in my basement. 1 is a 3" from the first floor and vanishes into the basement concrete. It services the 2nd floor bathrooms and kitchen. The 2nd stack is also 3" but goes into larger T fitting before entering the concrete floor. The T must be a 4 or 5", not sure. Can I use either stack for this bathroom? (Note: the stacks are 20 ft apart. I prefer to use the 1st stack as it is in the location I want the bathroom to be in).

Just getting started, still in planning mode. Looking for some pics of rough ins before they were covered with concrete if anyone has them.


Termite 09-25-2009 10:54 PM

There's a lot to take into account with venting. Lengths of pipe, drainage fixture units, pipe size...All play a role. AAV's (studor vents) are often a fairly easy solution. If you can do a riser diagram of your existing stacks and basement floor plumbing with pipe sizes and lengths I bet we can get it figured out.

Another consideration is backflow protection on the basement fixtures. The Int'l Plumbing Code requires backflow preventers on fixtures or fixture groups that are below the elevation of the upstream sanitary sewer manhole. If your street is flat then you need backflow protection for sure. If you live below the top of a hill (downstream side of the sewer) you need it. Most homes need it, some don't. You can't just put one in for the whole house either. It must be dedicated for the fixtures below the manhole elevation and cannot serve fixtures situated above the manhole. Better to tell you now than to fail an inspection on your ground rough plumbing!

smash403 09-27-2009 07:32 PM

If you have to ask these kind of questions and actually resort to a "Black and Decker" Plumbing book. I might have to say you're in over your head. Hire A plumber for your sake and that of your family. There are too many variables to consider when tying in a 3 piece to existing especially with inadequate experience in Plumbing

Termite 09-27-2009 07:46 PM

This is a DIY site, and we encourage people to do their homework before undertaking any DIY project. This is absolutely possible for a DIYer to do successfully as long as they know what to do before they do it.

JDC 09-27-2009 09:39 PM


I spoke with a contractor and they seem to indicate I could use the existing stack (3" that is the drain for my kitchen and 2nd floor bathrooms (2)) to vent the toilet and shower but I would need Studors on the other fixtures

You cannot vent anything into a waste stack. Now if that waste stack extends on up through the roof you can tie into it, but not until it is at least 6" above the flood level rim of the highest fixture served. In other words, if the stack you want to tie your vent into serves the second floor then you cant tie into it until you're above those fixtures.

As far as the tie in goes, it really shouldnt be an issue what angle the building drain is running at in relation to the proposed bathroom as long as the proper fittings are used and installed correctly. After all, thats what they make fittings for, eh?

thekctermite brings up a very good point about the backwater valve. If your building drain is below the next upsteam manhole then you need one. Thats something you really need to look into now. It blows when you have everything in then get turned down on your inspection because of something as simple as that.

Good luck and keep us posted

ferris13 09-28-2009 10:06 AM

Backwater valves, yeah, I need to look into that. I remember getting a plat of my lot, I believe the main sewer runs along the side of my lot. This would mean it probably serves the homes located above me. I live in a hilly neighborhood so I have a block of homes above my lot.

My first floor used to have a mini bar in the family room. It has since been removed. I may be able to tie into the vent (not sure what size) for that branch. This vent runs up the 2 stories, into the attic and then over to the main waste/vent stack. It would require me to run about 18ft horizontal make a 90 degree turn and then run another 10ft from the basement bath to where I would tie in. Does the length and type of run to create a vent play into the effectiveness of the vent itself?

homework time...


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