Don't step in the mystery hole!
December 26, 2011 2:48 PM   Subscribe

What could be the purpose of this mysterious hole in the middle of my brother-in-law's living room floor?

The hole was there when they bought the house a few months ago and is cut out of the carpeting and subfloor. It's obviously not professionally done, but someone put some thought into it, even cutting out a finger hole to pull up the insert and attaching the carpet pad to the back of the carpet plug. Down in the basement, the hole opens near the bottom of the stairs. Someone later screwed a board under the hole, presumably for safety reasons. We have no idea what held the round wooden section in the hole originally, but it seems like it was made to be removed via the finger hole. Any ideas what this hole was for?
posted by Joleta to Home & Garden (67 answers total) 26 users marked this as a favorite
Stripper pole?
posted by Nattie at 2:51 PM on December 26, 2011 [4 favorites]

Response by poster: Amendment: My husband says it's not a finger hole, but the place where the saw went in to cut the larger hole.
posted by Joleta at 2:53 PM on December 26, 2011

If that's a woodburning fireplace, maybe it was made to pass up pieces of wood from the basement?
posted by apricot at 3:01 PM on December 26, 2011

Do you have a gas fireplace, and is the house built on a crawlspace? If so, it may be some kind of access panel to get to the gas line cutoff. Usually, these are done with a smaller brass fitting on the floor closer to the fireplace, but I've seen some crazy diy jobs.
posted by gimli at 3:04 PM on December 26, 2011

I agree with apricot, probably a way to pass wood from downstairs.
posted by shoesietart at 3:05 PM on December 26, 2011

Sorry, didn't do a good job of reading the whole question.
posted by gimli at 3:05 PM on December 26, 2011

Floor Mounted Outlet, though that seems like a weird place for it.
posted by Confess, Fletch at 3:16 PM on December 26, 2011

That is very odd. If you were going to make a pass-through, surely there are more aesthetic places for it? Then again, some people do ugly things to their home. Is there nothing on the ceiling above the hole or in the floor below it? Doesn't really look like how I'd make a stripper pole if I were inclined to but maybe there's other clues?

That is one well-lit tree! Very nice.
posted by amanda at 3:34 PM on December 26, 2011

That floor outlet is 4.5" wide - the hole looks a lot larger than that ...
posted by carter at 3:37 PM on December 26, 2011

Laundry chute?
posted by JohnnyGunn at 3:44 PM on December 26, 2011

My immediate guess was foot plate for a pole dancing pole.
posted by DarlingBri at 3:44 PM on December 26, 2011

Is there any evidence that their was something in place under the hole to create a small storage space? I'm thinking maybe a place to hide drugs?
posted by COD at 4:04 PM on December 26, 2011

According to information obtained by reading the Amityville Horror and watching Ghost Adventures on TV, the hole is designed to let demons come up from your basement.

Oh, okay, that was unhelpful but also irresistible.

I agree with the people who think it was likely an electrical outlet messily made. People do weird stuff to their homes when they want something in a particular place. And if you've ever tried to get an electrician out to do a small job the right way, you'll sympathize with the poor guy who gave up and just did the best he could.
posted by driley at 4:12 PM on December 26, 2011

Response by poster: The hole is about a foot in diameter, and there is no wiring near it on the basement ceiling, so not an electrical outlet. The circle cut out of the carpeting is very evident, so probably not a hidey-hole for drugs. There is an outside door to either side of the fireplace, so storing wood outside would be more practical than in the basement. There is nothing on the basement floor below the hole, and the living room ceiling is vaulted and goes up at an angle, about 12+ ft above the hole. Nothing in the ceiling there. Laundry room is on the main floor, same as the living room.
posted by Joleta at 4:33 PM on December 26, 2011

My first thought was if you had a rug over the top of it you could use it to hide the cut out mark it would be a great place to hide things. The fact they have gone all the way through is weird.

Are there any drains down near it in the basement? Maybe they had a large fishtank and it was a way to drain the water for cleaning/water changes and the like? You could run a hose up through their for drainage and refilling and then drop it back down into the basement when done? Though if you were going to do that you think they would put it near the wall.
posted by wwax at 4:45 PM on December 26, 2011

All I can think of is that scene from Idiocracy where the guy's lounge chair is also his toilet.
posted by myselfasme at 4:45 PM on December 26, 2011 [7 favorites]

Pass through for a cat to travel, perhaps via a one- or two-story cat tree, to the basement, either for the pet's amusement or to keep the kitty litter far away? Insert your own basement cat joke here.
posted by carmicha at 4:50 PM on December 26, 2011 [1 favorite]

A foot in diameter is more like the base of a fireman's pole than a stripper pole. (nb I do not think it was a hole for a fireman's pole either.) I definitely like the idea of the fireplace wood shortcut the most.

But, um. Since they bought the house a few months ago, can't they just... ask the sellers?
posted by elizardbits at 4:55 PM on December 26, 2011

Previous owners used the hole (likely with some ductwork) to attempt to pull warm air from the fireplace into the furnace for recirculation.
posted by davey_darling at 4:55 PM on December 26, 2011 [2 favorites]

If you were mounting a stripper pole, there would be something marring the ceiling as well, and a hole would weaken the base rather than strengthen it.

I figure it has to be for something to pass through, but it's not really large enough for wood to come up or ash to come down (and there'd be a mess if it were that), so doubtful it has anything to do with the fireplace.

There's no ductwork, or the remains of such, nearby, and it would work very poorly if that were the case.

The only things I can think of are a hole for a hose of some kind, either a shopvac to pick up fireplace ash but vent the thing downstairs (sheesh, just get the right kind of filter), or a hose for some sort of water feature to drain below. It just doesn't seem worth it for a nonce task to screw up your living room floor; it would be something you do or use regularly or even all the time.

The location for something like this would normally be out of the way, unless location were dictated somehow, and I suspect it's the lower location by the stairs that was the deciding factor, somehow.
posted by dhartung at 5:03 PM on December 26, 2011

Agreed, it is not a stash place because it is about as obvious as you can get.

Also, I would not store firewood in the basement, because (a) you'd have to carry it down there, and then carry it back up; (b) mess; (c) damp, or at least the wood would not season. It is just really unusual.

I'd be wary of any heat recirculating ideas because it would be in the middle of the room, and chimney pipes can get real hot, and would damage the carpet/foam/ply.
posted by carter at 5:21 PM on December 26, 2011

The sheet metal bulkhead in this picture suggests to me that it might have been part of the cold air return for the furnace once upon a time. Having your passive exhaust fireplace chimney get into a race with the active draw of your furnace blower would suck. Literally.
posted by Kid Charlemagne at 5:42 PM on December 26, 2011

I have seen some older houses where the heating was done via radiators. The house had several grated holes, mostly at the edges of rooms, sometimes in the center of rooms, but under furniture(e.g. under the middle of the dining room table) to help with ventilation and get some of the upper floors fresh air. Maybe they wanted to fan in some of the cool air from the basement to the main living room in the summer to fight off using the air conditioning. The quickie repair would just be to pass the house inspection to sell.
posted by Nackt at 5:45 PM on December 26, 2011

Obviously they kept a wild beast in the basement, and had the hole in order to throw food down to it from time to time.


My first thought was "DIY installation of a floor safe," which they later removed and took with them, but it'd seem odd above a basement - how would they hold it in? Or disguise it from below?

I'm with the "ask them damnit!" club, although it might be weird to just get in contact with the former sellers and ask them out of the blue. But I want to know, now!
posted by Stormfeather at 5:45 PM on December 26, 2011 [2 favorites]

The wood looks like the original wood, but is the carpet and foam different? Could be a biological stain that had to be treated in a certain way, and the most economical way was to remover the wood, treat it, and replace.

Most likely an air return that was likely not completely installed for one reason or another.
posted by Yorrick at 5:54 PM on December 26, 2011 [2 favorites]

Response by poster: No drains in the basement near the hole. The living room has two outside doors, one on either side of the fireplace, so it would make sense to drain something outside through a door. No large fish-tank sized indentations in the carpeting.

The house was empty for about two years before my brother-in-law bought it. It was sold by the bank, so there's no way to contact the former owner to ask. Neighbors say that the house was rented for much of the time when it was occupied. The house is about 10 years old.

I like the kitty tree hypothesis, but there is a kitty door in the drywall at the base of the basement stairs (for use when the door at the bottom of the stairs is closed).

There is a ceiling fan at the peak of the vaulted living room ceiling, to aid in air circulation.

The carpet and foam padding are the same over the hole as in the rest of the room. It looks like the carpet and pad were cut away in a circle, then the wood subflooring cut out.

We independently thought of the "throwing food to animals/prisoners" idea but can't figure out why anyone would put the hole right in the middle of the living room floor. This is a single-story house with a large unfinished basement that runs under the whole house. I would have put a feeding hole in a closet floor. (I'm not actually being serious here.)
posted by Joleta at 6:12 PM on December 26, 2011

An interesting puzzler. I assume the hole is in the joist bay right next to the blinding light in your basement photo?

Stripper or other pole: unlikely.

Cold air return: I've never seen one in the middle of a room, and they are usually very large and perfectly square.

Ducting to or from fireplace: Not likely. Note that the joists don't seem to have any evidence of anything being attached near the hole, like strapping or brackets which would almost certainly be part of a ducting system.

I note the small initial hole is about a drill's width from the joist, and the hole itself is suspiciously near the joist. I'm guessing someone drilled the pilot hole upwards from the basement first, and then jigsawed the big hole from above.

But why? It might be possible they had a display fish tank up there and its plumbing was in the basement, but looking at the room that doesn't make much sense. Why would you stick in front of the fireplace in the middle of the room?

I don't have any guesses that cannot be explained better with easier things, but I was going to suggest a serious flood in the basement, and the hole is for the outlet hose from a big trash pump, leading out the door beyond the xmas tree. (But why not up the stairs? Or out what looks like a basement window? Why in the middle of the room and not to one side?)

The most puzzling thing is the location of the hole, in the middle of the room.

Incidentally, I would feel a lot better about that patch if it was resting on a couple of 2 x 4s nailed to the joists. The plywood and screws will probably hold indefinitely, but unless the patch is glued as well it's pretty iffy with just screws.
posted by maxwelton at 6:16 PM on December 26, 2011 [2 favorites]

Does the hole fall directly under the ridge of the roof, out of curiosity? Just speculating whether they needed to support the ridge beam for repairs at some point, and didn't feel the main floor would support it, and used a column resting on the basement floor. Not convinced this is a reasonable idea, but...?
posted by maxwelton at 6:24 PM on December 26, 2011 [1 favorite]

Yeah I keep coming back to the middle of the floor thing. You can and do route all sorts of things from basement to first floor - but through a 1' diameter hole in the middle of the floor ...?

Is there a gap between the two sheets of ply? I can see one hole in the top sheet (looking down), and a least three in the bottom sheet (looking up from the basement).

maxwelton's suggestion is the only thing I've seen that is reasonable ... and I would be upset if somebody did it that badly. Is there anything on the basement floor directly under the hole?
posted by carter at 6:29 PM on December 26, 2011

First, without that sheet of plywood held on by the screws, this hole would be wide open as the cut out itself would not stay. They could have built it so it could go in and out regularly if needed. It appears to be for a one time use both by the way it was "designed" and by the location in the room. This being renters mostly in the house and sold by the bank leads me to speculate that this was drilled on the way out. There was something in the basement that the last person who lived there wanted to move that either did not fit up the stairs and make a turn or was much easier to move out this way and since they were renters and probably knew the bank owned it, they did not give a huge sh*t and cut the hole. I think it was for something from the bottom going up, not from the 1st floor going down.

I once rented a house that had bullet holes in the kitchen (metal) cabinets. Sometimes there is no rational explanation for what a renter will do. Are there other homes in the neighborhood that have a similar floor plan that you could ask the owner if they care to speculate? Also, google the address, you might find the names of the renters. You never know.
posted by JohnnyGunn at 6:40 PM on December 26, 2011 [1 favorite]

I was thinking about the exit strategy theory, but for what? It looks like there is at least one basement window as well, so that would have to be unusable for this purpose.
posted by carter at 6:46 PM on December 26, 2011

Basement flooded and that was a makeshift exhaust air duct?

The only other plausible theory to me is the "needed to support the roof for repairs" theory. Are there any marks on the basement floor under the hole?
posted by gjc at 7:04 PM on December 26, 2011

Response by poster: The ridge of the roof is not over the hole. The vaulted ceiling extends upward and away from the fireplace wall.

carter: Thanks for pointing out the three holes in the lower cutout. I didn't realize that there must be two pieces of plywood cut out, one above the other. You can see from the basement side that the large hole was cut out from above.

I'm not at the house now, but I'll check with my brother-in-law about marks on the basement floor under the hole.
posted by Joleta at 7:07 PM on December 26, 2011

I was trying to imagine something that wouldn't go up the stairs but would go up through a '1 diameter hole, and couldn't connect the dots. I note the patch has been taken off its plywood support at least once.

One thing I think is probably against renters doing this before a bank-owned thing: I'm guessing the carpet would be replaced after renters and before sale. This has all the hallmarks of a quick-and-dirty solution to fix something else.

(What I'm really curious about now is what the home inspector had to say about this. If I was the inspector, I would be very curious as to what this was and would be pretty cautious about inspecting anything in its vicinity.)
posted by maxwelton at 7:08 PM on December 26, 2011

Looking at the "cutting out a finger hole" image, I'm struck by two things.

First, the hole in the wood is a much more regular shape than the carpet. Either someone's pretty good with a skill saw and much less able with a carpet cutter, or its the work of more than one person over time.

Second, the irregular polygon drawn in pen (?) on the underside of the carpet is surprising. It's hard to imagine a plausible reason to trace that cutout onto the back of the carpet, unless you were transferring dimensions to a brand new patch of carpet. Does the wooden cutout fit entirely within that polygon? Or, does the polygon fit entirely within the wood cutout? (The former seems more likely from the pictures.)

I wonder if the wood cutout sat beneath an polygon-shaped hole in the carpet beneath some appliance for a while. Later, the hole in the carpet was enlarged and a patch cut to fit when removing the original device. I'm not sure that brings us any closer to an answer, though if true, it suggests that an open hole covered with an object may have been the original plan.

As far as what it's for, a wild guess would be some sort of homebrew radiator, perhaps coming from an iron stove or similar in the basement. Placing that in the center of the room is still a little odd, but near the fireplace could make some sense.

Though, I prefer to imagine it's where the belts from goat powered treadmill used to pass on their way to fireplace mounted toasty-sandwich rotators, from back in the days when your house existed in a Rube Goldberg cartoon.
posted by eotvos at 7:30 PM on December 26, 2011 [1 favorite]

I know someone who has a hole in the living room floor for a Christmas tree.
posted by fromageball at 7:35 PM on December 26, 2011 [1 favorite]

Ask the previous owners. There is no logical reason for this. And...PLEASE let us know what you find out.
posted by tomswift at 8:19 PM on December 26, 2011

Portal, obviously. And they took the machine with them.

Seconding the PLEASE let us know. This is driving me nuts. I've asked all the handy mechanical minded dudes in the family, and they all think it's plain crazy.
posted by BlueHorse at 8:22 PM on December 26, 2011

Does the woodgrain match between the cut-out circle and the rest of the wooden subfloor? I can't tell from the pictures.

If it DOESN'T match, one possibility is that this was a clumsy repair of a very isolated floor-damage incident.

For example, suppose someone dropped a bowling ball from a great height and it made a splintery hole in the subfloor. You'd have to cut the carpet to get to it, then cut a smooth circle around the damage, then insert a new piece of wood to match the circle. The carpet may or may not be replaced too.

Same thing if there was some sort of horrible chemical spill, biological incident, or a very very small fire.

On an unrelated theory, here's a question I don't know the answer to. Suppose someone had a meth lab in the basement. Would that require a vertical exhaust thing or a tall condenser pipe or something?

I'm grasping at straws here, this is bizarre.
posted by mmoncur at 8:22 PM on December 26, 2011

Also, seconding maxwelton: Someone should have a professional look at that and make sure the repair is structurally sound. The way it looks now a 10-year-old child doing jumping jacks could easily knock it loose and fall downstairs...
posted by mmoncur at 8:27 PM on December 26, 2011 [2 favorites]

Response by poster: Hang tight until I can get more info from my brother-in-law, hopefully tomorrow.
posted by Joleta at 8:40 PM on December 26, 2011

I think my own personal long-odds bet will be 'meth psychosis.'
posted by carter at 9:00 PM on December 26, 2011

I know its been mentioned, but a floor safe doesn't seem all that implausible, that spot might have been covered with a couch.
posted by Confess, Fletch at 9:53 PM on December 26, 2011

C,F, there's no sign, from the low-res photos, anyway, that anything was attached to the joists near the hole, which is what you'd do with a floor safe.
posted by maxwelton at 11:03 PM on December 26, 2011

The living room has two outside doors, one on either side of the fireplace, so it would make sense to


There is a hole in the middle of your living room floor. Say that a few times. Do not toss one idea or another aside because it does not make sense to you. I repeat there is a hole in the middle of your living room floor that someone literally cut out.

Picture the Idiocracy dude, but instead of his toilet how about his recycling hole?

Dude: "DONE!"
*guy tosses empty beer down hole, which when uncovered actually has a device on it (empty 5 gal bucket turned upside down with hole in top) so he doesn't have to reach down to the hole*
Dude: "Babe!.... Babe!...... BAAAABEE!!!!!"
Dudet: "What!?"
Dude: "grab me another brew. Monday Night RAW is off the hook tonight"
*grumbling from kitchen*
Dudet: "here you go hon'"
Dude: "thanks puddin' cup. Seriously, HHH is kickin' some ass"

get a good mental pic? Seriously, I know some people who won't pick up their cans, but tell their wife that they can feel free to pick up the cans that he crunches in a little on the side. So the idea of the "compromise" being a hole to drop the empties to the basement seems just about right.
posted by zombieApoc at 6:57 AM on December 27, 2011

Cold air return: I've never seen one in the middle of a room, and they are usually very large and perfectly square.

I suggested a cold air return because of the bulkhead between the rafters and despite the observations you make (which are all pretty much on target) because I don't think this was exactly done by an trained HVAC guy. I'm thinking more that it was done by someone who who had a vague idea of how a furnace worked and was tired of the room always being cold (because of a leaky door to the outside maybe?) and rather than learning to balance their air flow they decided to get all brute force and fix the problem "once and for all."

So, yeah, I agree with you that everything about that begin a cold air return is wrong, but it's wrong the way that all the places I found "Touch and Foam" used in the vintage fixer upper that I bought were wrong. So very very wrong.
posted by Kid Charlemagne at 9:57 AM on December 27, 2011

It's possible that if it was used as a quick way to exchange heat from floor to floor that there was at one time a round metal grate of some sort in the hole. Then when they moved, they took out the grate, and put the original carpet-plywood cutout back in and hastily screwed together the support piece from the underside.

This -- like a lot of other suggestions -- is a stretch as it seems like there would be a better location to put a hole that wasn't in the middle of the room.
posted by buckaroo_benzai at 10:04 AM on December 27, 2011

This -- like a lot of other suggestions -- is a stretch as it seems like there would be a better location to put a hole that wasn't in the middle of the room.

If you didn't know what you were doing and were trying to warm the room, putting the hole in the middle would seem perfectly logical.
posted by COD at 10:07 AM on December 27, 2011 [1 favorite]

People do crazy stuff sometimes especially if they are crazy. I vote that the previous owner was trying to make a hole so that the voices in the basement could be heard more clearly.
posted by JJ86 at 11:39 AM on December 27, 2011 [1 favorite]

I didn't see it mentioned - is it possible there was a huge entertainment center at that location and they needed a space to plug things in? I know you said there isn't any electrical right there in the basement, but are there any signs that someone might have stapled one of those big orange extension cords along the basement ceiling?

But still - right in the middle of the floor? It's possible, I guess.
posted by CathyG at 12:08 PM on December 27, 2011

Joleta, we need more information. How about city/state/country? Urban/suburban/rural? Is a college nearby? Industry? Can neighbors give any clue as to who or what kind of persons rented the house? Single/family/roommates? Age bracket?
This is a worthy mystery, and I, for one, will stay tuned until we solve it!
posted by exphysicist345 at 12:51 PM on December 27, 2011

Response by poster: Still waiting for my bother- and sister-in-law to read your posts and respond. I'll post back when I hear from them.
posted by Joleta at 4:00 PM on December 27, 2011

My suggestion is a home recording studio. The carpeted room was the control room. The hole would be to accomodate the mic cables or snake leaving the mixing console and going off to isolation booths or whatnot in the basement. The hole may have been sized to allow a snake box fit through it. It's position in the center of the room makes sense - the console would be in the center of the room with cables exiting it and dropping through said hold right behind it, so nobody had to trip over them.

Any weird partitions or DIY sound absorbtion in the basement?
posted by werkzeuger at 6:16 PM on December 27, 2011

edit: ....dropping through said hole...
posted by werkzeuger at 6:18 PM on December 27, 2011

On the floor safe idea...perhaps the tenants were selling pot? There would still need to be some sign of support for it on the joists below, I think. The joists look like 2x12s on 12" centers, which, if true, means the hole is actually about 9" in diameter--the diameter of this popular and easy-to-get floor safe.

Note the safe is not able to be mounted by its lip, but secured via holes in the bottom. The depth of the safe would have it fall well below the bottom of the joists; it would need to be secured to some sort of suspended platform. I guess I would look for signs on the joists on either side of the hole that screws, lag-bolts or other ways to secure the safe were emplyed.

Were/are there dents in the carpet indicating a couch or other easily-moved piece of furniture was located above the hole?

All that said, one of the ideas of a floor safe is for it to be difficult to find. A crappy patch in the carpet would give the game away, and then a walk downstairs and a few minutes with a crowbar would see a thief walking away with it.
posted by maxwelton at 7:02 PM on December 27, 2011

Any chance the renters wee doing this?

It could be something as silly as during construction-the apprentice/labour OR past renters etc. cut something round out ON the floor and this is the patch they did.

A hole to pass wood might be a good explanation-never underestimate laziness and it's "motivation" LOL

WAY too large for an electrical floor outlet.

A floor drain body meant for wood floors is "about" that size but I cannot imagine a floor drain being in that location.

A hole to transfer heat to a cold basement maybe?

I cannot see you house layout-is it possible the fireplace was added and originally a powder room /toilet was going in that location?

Good luck with your mystery

Maybe neighbors might know?
posted by plumberonkarst at 11:08 PM on December 27, 2011

Hey, coming late to this one: I'm confused about something. In the picture in the living room, the hole is about 4 or 5 feet from the fireplace, and at least as much from any other wall. However, in the picture from below, it looks like there is some sheet metal ductwork right next to the hole going up to the room above. I can't see where the hole is in the the basement, but I am confused as to what is going on there. Is that duct not going up through the joists next to the hole and into the space above, or does it just terminate there (or maybe it is just turning and moving through the joists)?

One thought I had was that there was some very nasty stain, that required the cutting out of a plug of carpet. Then, they realized the stain also seeped into the wood, so they replaced that as well. However, that carpet pad looks like it is the same piece that was there before (unless they cut that odd shape out perfectly by hand). Likewise, the wood grain looks contiguous so the plywood was not replaced, just cut out.

I was also thinking perhaps the layout was different before and the hole could have been for something in a wall like a laundry chute or trash chute, but if that was the case then the carpet wouldn't be wall-to-wall there, or if it was carpeted after the fact they wouldn't then go in and plug up the hole.

Since there is no lip to catch the piece, it would just fall through if that board wasn't screwed over it. So, the board wasn't put there to end the use of the mystery hole. In other words, whenever the hole was cut for whatever reason, it was either always open or the board was put over it right away. So, there was some always-open use such as a chute/vent, there was a temporary need for the hole such as a support going above, or it was removed and replaced for something like a stain. Or perhaps there was a terrible squeak there, and they though cutting around it would resolve it.

I think once you explain how those ducts work, we can figure it all out.
posted by This_Will_Be_Good at 9:20 AM on December 28, 2011 [1 favorite]

Response by poster: Sorry to be so late with more information. Here's a message from my brother-in-law (the homeowner) and some floor plans: living room, living room elevation, basement

"In the basement:
The wood grain matches at the cut. And – The ‘finger hole’ was cut from the basement. The hole was cut from above. The flooring is ¾ inch with a ½ inch plywood board attached with screws (removed once?). No odd markings on the flooring or joists.

The duct work is for the cold air return on the furnace. All of the ducting looks original – nothing odd.

The existing electrical gang box looks original and all the knockouts are in. The conduit looks original too.

The mechanicals were original when we bought the house. We had the furnace replaced in November, still need to replace the water heater.

All the electric, plumping and gas lines look original. The water heater and furnace are gas. We have a gas starter in the fireplace and a gas line going outside for a grill on the patio.

The basement has a large escape window about 20’ to the right of the hole. Also – the basement is unfinished."
posted by Joleta at 1:38 PM on December 29, 2011

Another vote for cold air return. Possibly mounted a fan over the hole.
posted by ambulocetus at 2:52 PM on December 29, 2011

I still can't tell where this picture (the hole) is located in this picture (the basement).

Also, I think there is a clue in the carpet plug & pad combo. What is that thing between the carpet pad and the carpet plug? It looks like some odd octagon of rigid material holding the carpet and pad together?

The carpet pad on the plug looks like it fits into the odd ragged edge of the surrounding carpet pad perfectly. So, that would be original. If the drill hole from beneath was cut first, you would expect the spade bit or circle bit to cut into the carpet pad. So, my guess is that the hole in the carpet was removed first. So, whatever need there was for the hole was probably coming from the top (stain, damage, location of grate or vent).

So, the carpet was cut away and the pad was ripped/torn up underneath that. Then, the hole was drilled up from beneath near the floor joist so that when the circle above was cut with the saw it would be totally within the space between the beams.

Then, mystery.

Then, either a new patch of carpet was cut and applied to the original carpet pad chunk (with the odd octagon between), or the original carpet and pad were put together to make the plug.

So, why would cut an octagon. Well, if didn't have a good means of cutting a circle, it would be a quick way of rough-cutting tangents for a piece big enough to fit a circle or cylinder. For example, I was using a box cutter or carpet knife.

So, something like a cylinder or circular plate was placed down on the original carpet. Then, someone made a series of straight cuts to cut out the carpet that was there. This was torn up and the whole-hole cutting process above was followed. Then, the old piece of carpet was used as a template for a new piece of carpet used as a plug and glued to the old carpet pad.

This tells us the process, but not what the use was. The circle/cylinder template used for the hole means that a circle or cylinder was needed to pass through there. All the ducts down below are square, so this probably didn't tie into that ductwork.

What are some things that could work? Well, a circular grate for some sort of vent is possible. Also, a temporary use -- for example, some sort of tube was needed to pour concrete down below (but they could just go down the stairs or in through that basement window). So, if it wasn't just a plate/grate, maybe it was a cylinder or some fixed object that was there passing through. A marble column? The plate/grate makes sense if the current use in that room is exactly the same as it was before, and not something unusual.
posted by This_Will_Be_Good at 3:27 PM on December 29, 2011

One other thought...perhaps the hole was part of a radon mitigation system? I just came across this and this, maybe there was a radon mitigation system installed there, that was either replaced or no longer needed (or hopefully not just removed prior to sale). I don't know enough about radon to know whether these things are only needed until the radon levels return to a safe level.
posted by This_Will_Be_Good at 4:49 PM on December 29, 2011

Here's some things that seem apparent on further study:

1) The hole is indeed a foot in diameter, those are almost certainly 2 x 12s on 16" centers. Sorry.

2) It looks like the octagonal thingy is there not to hold the underlay to the carpet, but rather to hold the four pie-slice shaped pieces of carpet together.

3) This means they knew they needed a hole but cut a cross-pattern in the carpet first to minimize the damage to the carpet (!). Slices are easy to hide if they go too far. Be interesting to examine the edges of the main carpet pieces to look for evidence of these exploratory cuts.

4) Once the drill bit came up from below, they knew where the joist was, and crudely cut a circle from the carpet based on that, and then even more crudely from the underlay. This crude cutting suggests they weren't going to give a rat's behind about the aesthetics of the carpet.

5) On the other hand, the hole in the subfloor is quite neatly done. If they just needed to get something out of the basement, a crude free-hand circle like the carpet would have been plenty good enough. The "perfect" circle suggests something needed to fit there (it would be that the saw guy was a neat-nick (or had a handy pie pan to use as a guide) and the carpet cutter didn't give a shit, too).

6) If something was mounted there and no one gave a crap about the carpet hole, it suggests whatever it was had a decorative base. It could be a trick of the light, but in the photo of the carpet plug in place, there does seem to be a more regular circle surrounding the cut-out, perhaps about 16" in diameter? (This is a stretch, sure.)

7) Why would this patch need to go on to its plywood support, come off again, and then go back on, using different mounting holes?

Still, at the end of the day, I don't really have a clue. There's no evidence of staining on the carpet or plywood, really. Underneath it looks like there might be some water staining around the hole, but it's pretty ambiguous and could just be from when the house was built.

I take it there is no "ring around the basement" indicating a lot of water at some point?
posted by maxwelton at 7:39 PM on December 29, 2011

Response by poster: The carpet plug is the original carpet that was cut out in a circle, not a replacement patch for a stained area. I think This_Will_Be_Good is right about the octagonal area being a quick way to cut away the padding with a carpet knife. The visible octagon is the backing of the foam pad, where the foam was torn away. Someone glued the pad onto the back of the carpet circle so that they stayed together when the carpet plug was replaced (to keep the plug level with the rest of the carpet).

The hole is located between the floor joists above the glaring lightbulb in the fourth photo.
posted by Joleta at 9:15 PM on December 29, 2011

So, if I am standing under the hole looking up, like you are in this picture, then I am sort of just in front of the end of the door in this picture.

In the latter picture, I would be facing the camera as I look up. The light in the picture is above me and to the left. If that is the case, then what is that aluminum sheet between the floor joists in the first picture?

Well, one guess was the Radon vent (might be something you want to check into as they should have disclosed that to you -- if that is it, you should be able to find holes in the slab in the basement). I am thinking that one other idea is that this may part of some crude attempt at an air circulation system (perhaps like this) that was quickly installed either during a hot summer or a cold winter. So, maybe during the summer, that hole was blocked up and replaced with the carpet plug to keep cool air in the living room. And then during the winter it was opened up and covered with a grate to draw cold air up from the basement and into the fireplace?
posted by This_Will_Be_Good at 11:41 AM on December 30, 2011

If someone needed to put a jack on the basement floor to prop up the roof beam, they would of course want to put it directly under the beam. Question: If you tried to do that, could you? Or is there stuff in the way (heating ducts, electrical conduit, whatever) at that point of the basement ceiling, which would prevent you from making a hole there? In other words, I'm looking for some reason to put the hole where they did, missing the furnace and water heater and all the stuff in the ceiling. To jack up the roof beam. Plausible?
posted by exphysicist345 at 8:35 PM on December 30, 2011

Response by poster: So far, no "best answers," but many good ideas. I've got to plan another trip to my brother-in-law's house and take more photos. And I'll mark them up so that the location of the hole from below is more evident. It may be a while, so check back here again.
posted by Joleta at 7:07 AM on January 1, 2012

I have come to accept that some things are better left a mystery and I think this is one of them.
posted by JohnnyGunn at 12:30 AM on January 2, 2012

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