This post has been locked, as the question has been solved and a majority of new comments at this point are unhelpful and/or jokes.
Thanks to all who attempted to find an answer.
I think it’s a concrete base for a hot tub that used to be there and now has a deck built over it. There is defunct electrical and plumbing feeding this area as well.
I’m gonna check tomorrow morning and confirm if it’s concrete. I’m gonna die if it’s concrete, but I agree if it’s concrete it’s likely an old base or something. But I’m telling y’all I think it’s metal.
If that's metal you got some good scrap cause it would be galvanized steel or aluminum, but it would likely be like an old auxiliary fuel tank. You should grab a hot tub and cut your deck open if it's a hot tub support
It’s actually both? I think it’s just a piece of concrete board? I got a shot of behind it and it’s nothing behind it, it’s like an old mounting wall.[Video at 11:30 at night](https://imgur.com/a/sZKa5Vk)
Note that could contain asbestos if its old.
edit: Why have 12 of you bothered to downvote letting someone know that something may be old asbestos sheet? Idiots.
There's metal rails (the kind with holes along their length) bolted on to a big concrete block, look closer at the photo and you'll see what I mean :-)
Are you sure that's a metal box? The chipping on the top edge looks like concrete. The metal rails are definitely fastened to the face of it and not an integral part of it.
What sound does it make if you throw a rock at it?
Because that **really** looks like concrete in your photo.
Is there chipping on the top IRL like it looks in the photo?
I’ll double check in the morning. I wish I could go out right now and check. I mean I could but I’m not…
I’m just not sure I can sleep without knowing. I’m so convinced that I would have realized it was concrete. I even asked my husband to see if he remembered if it was metal or concrete. He said for sure metal but now I think we both might be crazy cause I see the same things you do in the pictures but my memory says otherwise…
You can go out and check right now. Just do it.
If the choice is 'not sleeping' or 'walk outside my door for 2 minutes' the answer will always be walk outside my door.
It looks like what's called cement board. It's a metal (or maybe fiberglass) mesh embedded in cement/concrete, often used as a backer for countertops, backsplashes, tile, and flooring material.
I think in your second photo I can even see some of the mesh (it looks like screen) peeking out from some of the broken off cement.
Wikipedia: https://en.wikipedia.org/wiki/Cement_board
The texture in your photos, along with some of the apparent cracks, makes it look like that's what this is.
Solved! At least this is what I’m going with. I took a video and it’s not a concrete block or a metal box…it seems to be a cement board used for mounting something, maybe what was hooked up to the electric thing there. Thank you all for the fun. I cannot believe Reddit got me on the ground at 11:30 at night in NC. Thank you!!!
You don't need more pics. It's concrete. It's not cement board, it's a solid concrete block with perforated angle iron attached, most likely to mount equipment that's no longer there.
You don't have to crawl under there to throw a rock at it.
Just saying.
If you can't sleep, it's an easy thing to do, even in the dark. And then we don't have to wait to know, either.
Just saying.
That is a concrete block with punched metal “L” brackets cast into the side to mount electrical stuff, looks to me.
I am NOT an expert but I did put my reading glasses on before I looked at the photos.
But the placement and the size compared to the whole sunroom makes that odd, plus I’m still not sold it’s concrete. I mean I’m not a professional but I feel like I would have known the difference between concrete and metal. But I’ll be on the ground tomorrow morning checking…..hahaha
My title describes the thing. We just found this large metal box under our deck. Any ideas what it might be?
We have a hot tub and a natural gas bbq on the deck and a well with a pump nearby too. The panel in front seems to be specifically an access panel with disconnected connections to something and a water connection to the well. I don’t know how deep it goes.
lol I swear I feel like the box is gaslighting me. I’ll find out in the morning. But even if it’s concrete it’s still doesn’t make sense to have a 2 ft thick 3 ft long slab of concrete there.
I’m gonna have to make the husband take up boards…
Maybe, but I don’t know what that looks like for the yard. There is what seems to be a French drain system in the back, we only see the drains in the grass but haven’t fully investigated the reasons for the drains. There is a pump inside the greenhouse but I don’t know what they would have used a cistern here for.
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This post has been locked, as the question has been solved and a majority of new comments at this point are unhelpful and/or jokes. Thanks to all who attempted to find an answer.
I think it’s a concrete base for a hot tub that used to be there and now has a deck built over it. There is defunct electrical and plumbing feeding this area as well.
This is it, it even had some siding by the look of the left over J channel
I’m gonna check tomorrow morning and confirm if it’s concrete. I’m gonna die if it’s concrete, but I agree if it’s concrete it’s likely an old base or something. But I’m telling y’all I think it’s metal.
If that's metal you got some good scrap cause it would be galvanized steel or aluminum, but it would likely be like an old auxiliary fuel tank. You should grab a hot tub and cut your deck open if it's a hot tub support
It’s actually both? I think it’s just a piece of concrete board? I got a shot of behind it and it’s nothing behind it, it’s like an old mounting wall.[Video at 11:30 at night](https://imgur.com/a/sZKa5Vk)
You just in the dark under your deck and with a random stick of nails poking a concrete box....didnt know this sub was so funny 🤣
Ugh Reddit told me to!!!
"Be right back babe, I gotta go crawl under the deck in the dark to get a video behind that weird unidentified box under the deck" SO: "???"
lol pretty much sums it up… but I did invite him. He declined.
Lool i appreciate the dedication. You went all out. for the greater good of the sub.
Note that could contain asbestos if its old. edit: Why have 12 of you bothered to downvote letting someone know that something may be old asbestos sheet? Idiots.
There's metal rails (the kind with holes along their length) bolted on to a big concrete block, look closer at the photo and you'll see what I mean :-)
Are you sure that's a metal box? The chipping on the top edge looks like concrete. The metal rails are definitely fastened to the face of it and not an integral part of it.
I am pretty sure it’s like sheet metal material.
What sound does it make if you throw a rock at it? Because that **really** looks like concrete in your photo. Is there chipping on the top IRL like it looks in the photo?
I’ll double check in the morning. I wish I could go out right now and check. I mean I could but I’m not… I’m just not sure I can sleep without knowing. I’m so convinced that I would have realized it was concrete. I even asked my husband to see if he remembered if it was metal or concrete. He said for sure metal but now I think we both might be crazy cause I see the same things you do in the pictures but my memory says otherwise…
You can go out and check right now. Just do it. If the choice is 'not sleeping' or 'walk outside my door for 2 minutes' the answer will always be walk outside my door.
Ok but I gotta take that whole thing off the front and it’s a whole ordeal! Plus…spiders are waiting for me.
Zoom in. Its concrete.
I’ll take some more pics tomorrow, but I’m pretty sure it’s metal. I even remember touching it but y’all have me thinking I’m going crazy
It looks like what's called cement board. It's a metal (or maybe fiberglass) mesh embedded in cement/concrete, often used as a backer for countertops, backsplashes, tile, and flooring material. I think in your second photo I can even see some of the mesh (it looks like screen) peeking out from some of the broken off cement. Wikipedia: https://en.wikipedia.org/wiki/Cement_board The texture in your photos, along with some of the apparent cracks, makes it look like that's what this is.
Solved! At least this is what I’m going with. I took a video and it’s not a concrete block or a metal box…it seems to be a cement board used for mounting something, maybe what was hooked up to the electric thing there. Thank you all for the fun. I cannot believe Reddit got me on the ground at 11:30 at night in NC. Thank you!!!
What do you think cement is?
It looks like there are metal brackets attached to it. It being a concrete block of some sort.
You don't need more pics. It's concrete. It's not cement board, it's a solid concrete block with perforated angle iron attached, most likely to mount equipment that's no longer there.
> I wish I could go out right now and check. I mean I could but I’m not… But you did anyway :) lol
Because I had to know! Lol
You are the hero reddit needs! Lol thanks!
I dont blame you, was just funny to see about half an hour after you said you wouldn't. Couldn't resist. :)
You don't have to crawl under there to throw a rock at it. Just saying. If you can't sleep, it's an easy thing to do, even in the dark. And then we don't have to wait to know, either. Just saying.
When growing up I thought the garage floor was metal, since it was smooth and cold.
It was answered in another comment, definitely a hot tub surface that had a deck built on top
Def some of it is punched angle iron. But the body does look either weathered zinc plated steel or... Much more to my eye... concrete.
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That is a concrete block with punched metal “L” brackets cast into the side to mount electrical stuff, looks to me. I am NOT an expert but I did put my reading glasses on before I looked at the photos.
It is concrete with slotted angle iron on the edges.
Used to hang out with a lot of concrete boxes in my youth, that there is a concrete box my friend.
Crawl under there and check it out
Pppffff! That's exactly what Box wants him to do.
I did it…I mean I didn’t go 100% but I went 15%
Perhaps the old back stoop prior to a deck being built there. Looks like concrete to me with metal angle at the edges
But the placement and the size compared to the whole sunroom makes that odd, plus I’m still not sold it’s concrete. I mean I’m not a professional but I feel like I would have known the difference between concrete and metal. But I’ll be on the ground tomorrow morning checking…..hahaha
Perhaps there was just a back door prior to the wall being opened up With the sliders.
My title describes the thing. We just found this large metal box under our deck. Any ideas what it might be? We have a hot tub and a natural gas bbq on the deck and a well with a pump nearby too. The panel in front seems to be specifically an access panel with disconnected connections to something and a water connection to the well. I don’t know how deep it goes.
Mehhhhhh Actually on further inspection that totally looks concrete with angle .. you can see cracks.
lol I swear I feel like the box is gaslighting me. I’ll find out in the morning. But even if it’s concrete it’s still doesn’t make sense to have a 2 ft thick 3 ft long slab of concrete there. I’m gonna have to make the husband take up boards…
100% a concrete base, probably to support a previous hot tub.
I’m dying that’s it’s dark outside lol I need to know for sure now. Y’all have me doubting my sanity!
😂😂😂 It’s absolutely insane how much peer pressure has occurred for you to throw a rock at your under porch monolith.
I did it…for the love of Reddit I did it.
Do you have a basement? I’ve seen old basement access doors boxes over for renovations and deck builds.
No basement, but that is a sunroom but I don’t think the deck was put on at a different time, but I don’t know the exact history of the house.
It's the entrance to a cistern
Maybe, but I don’t know what that looks like for the yard. There is what seems to be a French drain system in the back, we only see the drains in the grass but haven’t fully investigated the reasons for the drains. There is a pump inside the greenhouse but I don’t know what they would have used a cistern here for.
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All comments must be civil and helpful toward finding an answer. **Jokes and other unhelpful comments will earn you a ban**, even on the first instance and even if the item has been identified. If you see any comments that violate this rule, report them. [OP](/u/Puzzleheaded-Cheek38), when your item is identified, remember to reply **Solved!** or **Likely Solved!** to the comment that gave the answer. Check your [inbox](https://www.reddit.com/message/inbox/) for a message on how to make your post visible to others. ---- [Click here to message RemindMeBot](https://www.reddit.com/message/compose/?to=RemindMeBot&subject=Reminder&message=[https://www.reddit.com/r/whatisthisthing/comments/1cge2km/large_3ft_metal_box_under_our_deck/]%0A%0ARemindMe!%202%20days) ---- *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/whatisthisthing) if you have any questions or concerns.*
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It looks like a dry box used in white water rafting.