Bathroom completion problems

[Rhaine86]

I need some help here on identifying the pipes in my bathroom as well as how to go about fixing a possible problem finishing the bathroom in my basement.

I have attached a photograph of the piping to show what exactly is in our basement now.

The blueprints for our home call for this to be a full bath- but in looking at the area it appears we are missing a drain. There is a drain in the concrete under where the bathtub lies, and there is a drain for what should be (again, according to the plans) a toilet (black pipe extending up). What I don't see is a sink drain.

To make the entire thing further frustrating is the fact that our cold air return ventilation (not shown) was installed a few inches too close to where the bathtub should be. In order to have a bathtub in this bathroom we have to place it slightly more forward than the original plans call for. This means we would have to either move the drain, or hope that a bend in the piping won't cause a drainage problem for the tub if we leave the drain where it is. We will be consulting a plumber to find out what would be best.

I'm guessing that the original owner (who was also the builder for the whole development) realized the mistake and figured the downstairs bath would just be a half bath and therefore did not have another drain installed. Had my family realized this when we were looking at the house we would have thought a lot harder about whether to buy the house because the only other bathroom in our home is a half bath! The owner decided to put in an oversize shower rather than a tub/shower upstairs- go figure.

In any case- we obviously have a few problems here. We definitely want to put in a tub (who would want to buy a house without the possibility of one?).

Out of curiousity- can anyone tell me what the copper pipe extending up from the concrete (lower right side of photo) near the others is for? I can't imagine something so small in diameter could be a drain pipe? The other copper pipes run the hot and cold water for our kitchen sink and I'm assuming can be connected to piping for a bathroom sink?

I'm hoping all of this makes sense. If anyone can offer help/suggestions/ideas I would greatly appreciate it. I obviously know very little about plumbing in general!

[LazyPup]

I would begin by examining the return air duct to see how difficult it would be to reroute it a bit to permit your required tub clearance.

The next step would be to determine if there is a trap under the floor for the tub drain. Hopefully that line is covered at this time so to check for a trap, remove the cover then pour a couple quarts of water in the drain. You can then look down the drain pipe and you should see water standing in a trap. (You may need a flashlight to look in the line)

Code will permit a short horizontal offset providing of course that you have sufficient vertical clearance for the bends and the required pitch from the drain opening to the waste & overflow tailpiece, but here again, the preferred solution would be to change the return air duct and permit the tub to set back where you really want it anyway.

In the photo it appears that both the copper risers have short horizontal stub outs that are capped off for future expansion. (its difficult to see in the photo but when I enlarged the photo it appears that the copper line on the left side has a stub out that is capped directly behind the righthand line in the photo).

The black ABS line that is stubbed up and capped off appears to be a watercloset(toilet) waste line however the cap appears to be much larger than the line. Code minimum for a watercloset drain is 3" inside diameter. The standard offset from the center of a closet flange to the finish wall is 12" however they do make waterclosets that will fit a 10" offset.

I suspect their original plan was to install a Tee in the 3" ABS riser and run an 1-1/2" horizontal fixture arm to the lavatory to provide the drain for the lavatory sink. I see two potential problems with that. 1. It would require running the line past the copper risers which could present problems and 2. If that 3" ABS stack is serving a watercloset on the upper floor you would be required to install a vent between the stack and the lavatory trap. (An unvented fixture arm may not be connected to a wetvent stack downstream of a watercloset.)

There is a second 2" ABS riser near the tub. From the photo it is impossible to tell what the purpose of that line is. I suspect it may be for the shower in the bathroom above, although i don't understand why they wouldn't just tie the shower drain into the 3" stack up in the floor joist area. Perhaps you can see that line in the floor joist area and provide additional information.

What is of greater concern to me is the larger ABS riser. At the floor it appears to be a 4" line up to the cleanout TEE, then it appears to be reduced to 3" from that point up which would be fine for a watercloset drain from the bathroom above, but:

Under the International Residential Code you must have one "Main Vent" which runs undiminished in size from the building drain through the roof. If this line is serving as the main vent it should not be reduced unless there is another 4" riser somewhere in the house.

Under the Uniform Plumbing code vent lines may be reduced to 1/2 the diameter of the line they serve providing the aggregate total cross sectional area of all vents is equal to or greater than the cross sectional area of the main drain. The main drain is a 4" line which has a cross sectional area of 12.54sq.in and the 3" riser has a cross sectional area of 7sq.in so you would need an additional 5.56sq.in of venting somewhere in the house.

[Rhaine86]

Wow- that was quite a lot of information for me to digest! Thank you for being so complete in your response. It is always appreciated.

First off, I measured from the center of the watercloset flange (which is 3") to the ABS pipe (I realize the wall will stop short of it). That measurement was 13.5 inches; however pictured just barely in the lower right of the photograph is the radon pipe (6"interior) that we had to get installed last Fall. I suspect we will have to hope that 10 inches from wall to flange will suffice as that pipe sticks out slightly farther than the ABS pipe.

Regarding moving the cold air intake- this is something we can look into, however alot of our duct work and our furnace is all located right next to one another- moving them may not be a feasable option; but again, we'll check into it. That's something we had not thought of.

It would be great if we could manage to do that- because from what I've been told, our toilet bowl would actually stick out quite a bit farther (possibly to the middle of the tub) and may look silly when completed.

The two black ABS pipes actually connect to one another (the one pictured on the left elbows to the right) about 4' up. I was told they were the vent pipes for the bathroom. Our upstairs toilet has it's own drain- everything up there appears to be separate from the basement.

I've attached two more pictures- one of the cold air return/furnace/water heater and another closer up view of the water pipes.

So... what a mess this has turned out to be! I thank you again for your quick response. All of your comments will definitely be helpful!

[Piper]

Out of curiousity- can anyone tell me what the copper pipe extending up from the concrete (lower right side of photo) near the others is for? I can't imagine something so small in diameter could be a drain pipe? The other copper pipes run the hot and cold water for our kitchen sink and I'm assuming can be connected to piping for a bathroom sink?

The 2" ABS pipe behind the toilet is probably the vent for the toilet. If so you can run a 1 1/2" arm over to the center of the sink .

The copper line in the floor probably is a loop to provide water to or from another area area possibly behind the tub. Look around for the other end of it sticking up through the floor some where.

[LazyPup]

The 2" ABS riser on the left side is definitely not a vent for the toilet. The Closet flange is only 13.5" from the larger vent stack. Toilets require a 3" drain line and under the Uniform Plumbing Code(UPC) a 3" line may run up to 6' from the trap to the vent. Under the International Residential Code(IRC) a 3" line my run up to 12' however if the only fixture served by that line is a toilet it may run an indefinite length without providing additional venting.

Code requires that we have a cleanout on the upstream end of a main drain or branch drain. A toilet can be lifted exposing a direct access to the line so a toilet is also classified as an approved cleanout access. Typically when designing a bathroom layout we begin by running the branch line from the closet flange to the main drain which then provides the required cleanout on the branch. We then install "fixture arms" from the branch line to the tub or shower.

Fixture arms serve as both drain & vent therefore there overall length is very closely regulated to insure they can provide the vent function.

Under the International Residential Code the maximum length of a fixture arm is calculated by dividing the line diameter by the pitch. BY example, a tub drain requires an 1-1/2" line and the required pitch is 1/4" per foot so the maximum length for an 1-1/2" fixture arm is 1.5 / .25 = 6'

Code allows us to increase the drain diameter by one nominal trade size so we could increase the line to 2" and the maximum length of the fixture arm would then be 2" / .25" = 8'.

The Uniform Plumbng code begins with basically the same formula but they then derate the permissable overall by approximately 40% thus under the UPC an 1-1/2" fixture arm is limited to 3' 6" and a 2" line would be limited to 5'.

After studying the photos I suspect that Rhaine86's local code is based upon the UPC and the length of the tub fixture arm exceeds the allowable length thus they have provided an additional vent within the maximum length of the fixture arm.

You could then install a Tee and connect your lavatory drain to either vertical.

In the attached photo I have shown the fixture arm in Yellow.