# What is this hole in my concrete basement floor?



## diytrying

I'm planning on finishing my basement, which is essentially a (dry) concrete box. Concrete floor, and concrete walls on all sides.

I was hoping the floor would be nice and level, because waterproof (just in case) vinyl would be easy to install, but the floor seems to dip slightly towards one wall and leads to this... square hole in the ground. It's almost as though it's a place for water to funnel to, but I have no idea why as the basement is dry even after the worst rainstorms. The worst of the moisture I have in there, is having to run a dehumidifier in the summer.

Anyway, if I am trying to eventually finish the basement - does anyone know what I would do with this, and the slight dip in the floor around it?

Thanks in advance for any insight - I am new to the home improvement game.


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## mako1

Looks like a floor drain from what I can tell by the pic.Is there a washer and dryer hookup close by?


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## diytrying

mako1 said:


> Looks like a floor drain from what I can tell by the pic.Is there a washer and dryer hookup close by?


Actually no, that's the strange thing. The washer and dryer are upstairs, and everything in my house runs on electric (no gas, oil, etc.) so the only piece of hardware in the basement is an electric hot water heater that sits on the opposite side of the room from this hole.

I don't think there's anything in there, like a drain.

Is it safe to use some leveling compound (is that what it's called?) to seal this hole up before I put in vinyl floors? Home Depot told me I could install waterproof vinyl right over the concrete, as long as the concrete was level (which it's not around this hole, and especially inside the hole!).


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## cjm94

If you dig under the dirt you should find a capped off drain pipe roughed in when floor was poured for future use.


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## diytrying

cjm94 said:


> If you dig under the dirt you should find a capped off drain pipe roughed in when floor was poured for future use.


I was about to go to bed but this comment got me so excited that I ran to the basement to dig it up!

Sadly, I got about 6-8 inches down and it is just flat concrete. Completely flat. I don't see any way there could be a pipe sealed down there, which leaves me baffled at what this thing in the floor is for (and how to safely work around it to put in my floor).

Thank you for your post - I hadn't thought to dig down there!


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## smyers

Looks like a post was removed that was embedded in the concrete. Like a old support post or a temporary one.


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## Chewbacka

I'd take careful measurements from the center of the hole to the room corners from every direction and then post it by the water heater or someplace it can't be missed. Then get a stainless steel plate to cover it by at least several inches on all sides and adhere the plate to the floor so it won't move around but would still be able to be removed at a later date if needed.
then take a 2' square piece if clear plastic and tape it to your floor anywhere you think moisture may be present. After a week if there is no evidence, or very little evidence of water on the underside of your plastic then you are probably good to go with the flooring.
Personally I used click lock laminate floating floor over a plastic pad and it has held up really well. It had to be cut to fit, but was well worth the effort. We had a flood when our addition was beginning and after mopping and dehumidifying for a long time we had very little damage. We did not remove the flooring to dry it out. YMMV.


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## joed

Looks to me like it was bigger at one time and someone has filled it in. Could have been a sump pit at one time. It is odd that you found concrete 8 inch down below the dirt. Support post idea would support the concrete under the dirt. What is above this?


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## landfillwizard

Do you think that there may have been plans to put a shower in the basement and they left room for a P-trap in the basement floor?


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## joed

landfillwizard said:


> Do you think that there may have been plans to put a shower in the basement and they left room for a P-trap in the basement floor?


That was my thought until he dug down and found concrete.


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## landfillwizard

They may have wanted to run drain lines above the slab and just the P-trap below the slab?


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## diytrying

smyers said:


> Looks like a post was removed that was embedded in the concrete. Like a old support post or a temporary one.


Perhaps a temporary support - I'm in the end-unit and that hole is probably about 3 feet from dirt (so it's not as though it is towards the center of the structure, at all).

Why there is some crappy quality dirt and rocks in the hole though - that really beats me. :laughing:


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## diytrying

Chewbacka said:


> I'd take careful measurements from the center of the hole to the room corners from every direction and then post it by the water heater or someplace it can't be missed. Then get a stainless steel plate to cover it by at least several inches on all sides and adhere the plate to the floor so it won't move around but would still be able to be removed at a later date if needed.


What a brilliant yet simple way of keeping track of it! Thank you for the tip!



Chewbacka said:


> then take a 2' square piece if clear plastic and tape it to your floor anywhere you think moisture may be present. After a week if there is no evidence, or very little evidence of water on the underside of your plastic then you are probably good to go with the flooring.


I did this months ago with plastic wrap and taped it as airtight as I could to one wall and the floor where a waterspot used to be (turned out to be a leak in my dehumidifier) but no moisture has developed at all. Would that accomplish the same thing that the clear plastic would? Or is plastic wrap somehow porous? The basement seems very dry and only had a slight moisture smell to it in the summer (dehumidifier emptied every few days cleared it right up). Now it's the winter and I haven't run the thing in months.



Chewbacka said:


> Personally I used click lock laminate floating floor over a plastic pad and it has held up really well. It had to be cut to fit, but was well worth the effort. We had a flood when our addition was beginning and after mopping and dehumidifying for a long time we had very little damage. We did not remove the flooring to dry it out. YMMV.


This is one thing I really can't decide on - right now the basement seems pretty dry, yes. But in the next 10 years, anything could happen - huge storm, damaged rain spout, water heater or pipe leak, crack in the foundation, etc. All of these things would lead to water in the basement. So I was looking at waterproof vinyl, which looks decent but I don't like because: (1) it's about 3x the cost of a lower cost vinyl or laminate option per square foot and (2) it seems thin and flimsy and the manufacturer recommends installing it right over concrete (I want the floor to be insulated from the cold, and as comfortable to walk on as possible). However, if (2) is the norm I guess I just have to bite the bullet and see how it looks. Is it a good idea to spend the extra money, but then never have to worry about filing an insurance claim once the inevitable water reaches the basement?


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## diytrying

joed said:


> Looks to me like it was bigger at one time and someone has filled it in. Could have been a sump pit at one time. It is odd that you found concrete 8 inch down below the dirt. Support post idea would support the concrete under the dirt. What is above this?


Pretty much nothing of value! I am the end unit in my row of condos so this is right next to the outermost wall. My hot water heater, pipes, and anything of note is on the opposite side of the basement. I am no handyman but I can't think of any functional reason why there would be a perfect square hole with a perfect smooth square bottom, filled partially with dirt and rocks, in that particular location.


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## diytrying

landfillwizard said:


> They may have wanted to run drain lines above the slab and just the P-trap below the slab?


It's a good thought, but I don't know why they would put a shower on the opposite side of the basement from the water heater. Personally, I would put it right next to the thing. I'm OK with Chewbaka's solution of simply covering it up in a way that can be uncovered later! My big worry was that it's functionally important to the building, but it doesn't seem like this is a real concern.

Thanks everyone for your insight


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## Chewbacka

If you prefer the click- lock laminate and pad solution go with it. I can tell you if you don't like the possibility of a cold vinyl with no pad show imperfections floor at way more money now you won't like it any better when it's done. Good quality click-lock laminate is virtually bullet-proof, is easy to clean and with a pad under it is comfortable.
Don't spend a bunch more money for something you don't want. The laminate can take a minor flood if it has to without warping so long as it is dehumidified quickly after it happens. It's literally like steel and does not absorb water.
I used Quick Step Eligna brand:
http://www.ifloor.com/laminate/quick-step/cherry-3-strip-7mm-laminate
It's been improved to include the pad on the board, from what I read briefly on the site I linked to above. Check it out. Lifetime residential warranty. I've had mine in a 1000sq' basement now for nearly 14 years or so. No problems whatsoever....:thumbsup:


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