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Rectangular hole in basement - What is it?

1740 Views 50 Replies 8 Participants Last post by  StrongEagle
Hello,

I recently moved into a new home. It is a 2-story home with a walk out, unfinished basement. The basement has roughed in plumbing for a toilet and sink. Opposite those pipes, by the stairs, there is a rectangular shaped hole filled with gravel. There is a pipe that is adjacent to the hole that goes up. This side of the basement is underground. I have run water through all the drains on the two other levels and I haven't heard water coming down this pipe. I excavated an entire bucket of gravel from the hole and haven't come across any pipes yet. Not sure if I should keep going or not.

Is this a location for a shower drain? A future location for a sump pump? The home inspection did not note any sump pumps nor did the previous owner. We have had some very heavy rains and there is no indication of water anywhere in this area. It was dry as far down as I dug. Possibly a radon vent?

I can't get plumbers to call me back for a quote to finish the bathroom and wondering if it's something I could do myself. I have zero experience in plumbing. Thanks

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Discussion Starter · #5 ·
Thanks for your reply. The pipe goes up into the basement ceiling, cuts over about 8 feet by the concrete wall and connects to another set of pipes and goes back down.

pic 1 = connecting to other drainage pipes
pic 2 = the combined pipes coming down
pic 3 = other pipes for sink (?) and toilet (dog for scale) the pipe in the right corner of the concrete wall is where the pipe in the first set of pics apparently leads.

edit: the house was built in 2001

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Discussion Starter · #7 ·
Thanks for the diagram. That makes sense. Since the former mystery pipe runs to what is likely drainage pipes below the concrete to the sewer system, would that be an acceptable place to put in a shower?
 

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Discussion Starter · #30 ·
Was there any more tie in spots?
I don't know if this helps or not. The pipe on the left (where the shower will go) goes up and connects to similar sized pipes in the ceiling (behind the big pipe) and then comes down the wall on the right. Above and to the right (not pictured) there are several pipes from the laundry room and kitchen sink on the main level that seem to tie in there.

Is that what you mean?

Thanks for your patience with a newb...

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Discussion Starter · #31 ·
It looks like most of the drain and venting is installed and connected. You need water piping, fixtures and walls of course. The waste & vent is the most difficult.
If you are somewhat handy you can wrap this up. There enough pros and well experienced people here to help out. You can start a 'project thread' and get all the input you need (y)
Thank you! I appreciate it.
 

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Discussion Starter · #34 ·
Now I'm just more confused.

Pipes on the right mostly make sense. Pipe on the left you said the kitchen sink ties into the same line that it ties into.

You had a picture of a wye (tie in) under the slab. Is that where the kitchen sink ties into?

I would not think so and presume you got mixed up.....could be me though! 🤨
I'm sorry. I'm sure I'm the one confused. Lots of new terminology. I also took the pictures from opposite sides which isn't clear for people not standing in the space.

The pipe on the left of the last picture goes by the rectangular hole filled with gravel. That's the only pipe I can see below the slab. I've not heard any water running down this pipe. Water from the kitchen sink and washer from the main level seems to come down the pipe on the right.

At the far back right of this picture the pipe comes from the bathroom sink on the main level.

In my attempts to explain, I think I'm making it worse. At least I know where the shower should go now.
 

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Discussion Starter · #37 ·
Is the kitchen sink the farthest away in the this picture where i have marked it drain.
View attachment 727839

That is a bathroom sink immediately above that area you marked. The kitchen sink is further behind me where I stood to take the picture and seems to run to the area in the top right corner of this picture. There are a lot of pipes and water lines in that area, hot water heater, hvac, etc.

I’m assuming all those join the main line out of the house below the slab. The entire basement is concrete expect for the hole with the gravel.

thanks!
 

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Discussion Starter · #39 ·
Usually they leave the pipe sticking up for the shower and they put a foam block around it with just a skim coat of concrete. So if you want or need to move it a little you can remove the foam and wiggle the pipe,
So for what ever reason they did not do that for you. Maybe they thought you might break concrete and move it anyway.
So where in the bathroom would you put the shower. I think it will connect to that pipe under the floor but you are not limited to where.
That's a good question that I will leave to my wife to figure out (-; personally, I'd rather not have to break up more of the floor, but since it seems some of the "harder" things are already setup, maybe we can go that direction.
 

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Discussion Starter · #40 ·
The pipe by the hole is a vent and you shouldn't hear water come down it.

Now let's see where we went wrong....lol

Under the slab you took this photo. This is what I asked....where does this go?

It appears to be plumbed for a bath tub.
View attachment 727841
I'm not sure where that goes. Do I dig out around on either side to see where?
 

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Discussion Starter · #46 ·
Same. It ought to be there for a reason. Some more digging and poking around is in order.

And, again the lines that go vertical then horizontal part way up the wall, group together are the vent stack lines, ensuring proper drainage and flow of the waste lines, by letting air in from the roof area. They possibly tie in somewhere with the bigger main stack.

Maybe through the realtor, or directly, reach out to the previous owner, to ask about the purpose of the hole, how, what, why, ... what the intention was?
I think we're at least the 4th homeowners of this house so that may be tricky. Every question we asked about the house to the immediately preceding homeowners was met with "I'm not sure" or "I don't know" so they were not very helpful. I'll see what I can find around the pipe that is there now. I'll also ask around with some neighbors as many of the houses in my neighborhood have a similar design.

Do you think there is a possibility I could tie into that pipe that is beneath the slab? Sounds like there probably will be some concrete work unless I can't find a pipe sticking up in that hole.

Thanks!
 
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