I need some advice. I have a <1 year old home in which I intend to finish the basement. It has existing rough-ins for a toilet, sink and shower. The problem is that I don't like where they are. They create a bathroom that is too small, and the overall location doesn't maximize the use of the space. All the rough-ins are located within 10-12 feet of the main stack, and I only want to move them slightly. I want to move the toilet rough-in over about 5 feet, the tub rough-in about 2 feet, and the sink rough-in about 3 feet.

I'm ready to rent a 70lb. jackhammer to break up the slab, but before I do it, I need to have a plan. I don't want to do unnecessary work. Do I just break up the concrete between the existing rough-ins and the new locations I've identified and lengthen the pipes? Or should I seal off the existing rough-ins and run straight from the new location to somewhere else? What is the required angle for the new pipes? Any advice will help.

I know this part of my project is probably best left to a professional, but I'm ignorant and I'm cheap - at least I know it! With some good advice I'm convinced I can get the job done. Thanks.

I assume you have the insurance money to pay for the half inch crack that might just run to the walls of your foundation and the ensuing water that will creep thru said crack this spring? Jackhammer?

I would cut or core what i needed.

Was the concrete saw and the coring machine too pricey for you to rent also?

Good luck.

the required angle for the pipes is 1/4" per foot. there may be vents off the pipes you want to move. if you move pipes too far away from their vents, you will not pass inspection.
unfortunately, you won't know what you are dealing with until you open everything up.
sometimes, plumbers install fittings with their shoulders butted together. can't really cut them back as their is no pipe to glue onto. need special tools to deal with this scenario.

I have seen jobs with the best advice, direct from the city's building department, and the homeowner still made an installation that had to be cut out and thrown away. There is no way to tell from what you have written, which way will be the best one, because you don't know how the pipes are arranged under the floor.

Thanks for all the advice. My initial instinct was to cut through the concrete, rather than pulverize it with a 70lb jackhammer. That's the last time I listen to the advice of my local Home Depot tool rental guy! Incidentally, it's cheaper to rent a concrete saw than a jackhammer, so that's what I'll do. I don't think I will require a coring machine for this job.

I've asked for drawings of the pipe layout used by the builder in my subdivision. Of 200 houses in my subdivision, there are only 3 different models, so although the actual layout under the concrete may not precisely match the sketches, it ought to be pretty close.

I'll follow this up with a better description complete with sketches and photos once they're available. More to follow!

I usually use a diamond blade in a Skil Saw then pulverize. Wet cut for no dust just mud.

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I always use a jackhammer...works very well....you dont need to cut the floor if you dont want to. the only difference will be a nicer cut line. I have never cracked the concrete other than where i wanted it...wear a dust mask(concrete dust is very bad for you).

When moving your pipes around you may exceed the vent limits on the tub/shower. you have 8' trap to vent and you could be at 7' already..i dont know without looking at it...it will probably be fine though since you say they are close together...

Redwood, don't you worry about electrocution performing a wet cut with a Skillsaw? Or do you have a trick that you can pass along... I considered taking that route myself but couldn't get comfortable with the "wet" aspect of it.

GFCI with a double insulated saw and not a lot of water just enough, I actually use the same spray bottle that I use when soldering. The Skil Saw has a slow enough rotation that it doesn't sling the water all over and dry out the cut.

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i hope you dont have post tension cables in the slab instead of re-bar. if cables the jackhammer is the way to go

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PLUMBERS "Protecting The Health Of The Nation"

If it even comes close to the drawing it would be surprising. The piping is installed however the plumber decided to do it that day, and looking at a drawing from an engineer is usually the last thing he would do.

Good advice from everyone. Here are the are the floor plans for the existing area, and how I propose to modify it:



It shows the general location of the existing rough-ins, where I propose moving them to, and the relative location of the main stack. The existing rough in for the sink has a vent stack that rises out of the slab and connects into the main stack near the ceiling of the basement. Would it be correct to assume that the rough-ins for the shower, sink, and toilet drains run separately in a direct straight line to the main stack? or would they join somewhere prior to the main stack and connect in a single line?

For the new plumbing, should I just extend the drains from the existing rough-ins, or should I just seal them off and run new lines from the main stack?

The builder's customer service guy is going to talk with the plumber that does all the work on homes of the same model in my subdivision to find out how he typically does the connections beneath the slab. As soon as I find out, I will update.

Thanks again.



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hard to say how they connected the plumbing under the floor. strange to see the vent coming from behind the lav instead of the toilet.

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PLUMBERS "Protecting The Health Of The Nation"

a wet vent will always come up behind the lav.

This project is not a simple do it your self project for most people. Its not just moving a pipe a few feet. You are relocating and switching fixture locations back and fourth. You will have to tear up the old pipes completely and Repipe the whole bathroom group. The original way you have it piped is pretty standard. I think 90% are done that way on the houses i rough. Id strongly consider leaving it to save money. Its not a bad layout. Busting concrete and doing the project will not be fun. It will cost over a thousand if you pay a plumber to do it. good luck though!

didnt say it wasnt done right just said it is strange to see it. very few vents run that way here. but then again very few basements here also

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PLUMBERS "Protecting The Health Of The Nation"

that is how I do it whenever possible. It makes a better lavatory drain, and the toilet doesn't care where its connection to the vent is located.

I am doing a project very similar to yours and I was wondering if I could pick your brain.

Did you end up renting the concrete saw? If so, did you use a diamond blade or a different type? How many feet of cutting did you have to do and how long did it take you? Did you use a wet or dry blade? how thick was the concrete you were cutting?

Did you have to break any of the existing waste lines under the floor to put a tee or branch line in? If so, how did you do it (I have no play in my existing lines buried under concrete)?

Thanks so much! If anyone else has experience here, please chime in!!

How did the project turn out? Any pictures?

Thanks,
Brian

In the end, I decided not to relocate the rough-ins. Even if I did it myself, the cost in terms of man-hours, equipment rental, materials, and risk of screwing something up outweighed the benefits of having a larger bathroom. It is just a basement after all, and a full bath is a full bath when it comes to resale value. I will definitely post some pictures to this forum as I work on the plumbing mechanicals, but right now I am moving into the framing phase of the project and that will take a few nights and weekends worth of work.

I want to continue posting the progress of my complete basement finish project in a forum, but since the project includes framing, HVAC, electrical, finishing, etc. in addition to plumbing, the PLBG forum is probably not the place to do it. Can anyone recommend a good forum that will enable me to post pictures and get a good volume of quality input at the same time?