Mystery Noise Coming from Interior Wall
About 2 months ago we started to hear a strange knocking coming from an internal wall in our house. The knock usually occurs in the middle of the night but sometimes it happens in the evening and sometimes in the morning.
There were here a few theories we had…
1. HVAC expanding/contracting – our neighbors have the same model and have opened this wall up before in their house, no vents
2. Water pipes- again, neighbors report no pipes
3. Expansion / contraction – this is our last idea left but have no way to verify nor anything to fix.
We are able to catch the sound on our cameras so I posted one to this thread. Usually it’s a double knock but sometimes it’s a single one. And ideas on on how more precisely troubleshoot this to work toward a fix would be appreciated!
reference: location is Orange County CA so daytime is usually low 70’s and night is mid to upper 50’s. Basically some of the least extreme temp swings one could
imagine.
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Replies
T.D.,
Ghost? I really have no idea.
The first thing for you to do is to try to see if the sounds align in time with anything outside. Does the sound occur when the outdoor temperature changes some amount (or more? Does the sound occur when the sun starts to hit the wall? When the sun stops hitting the wall? When you run the hot water? When the heat or air conditioning starts, or stops?
If you have sounds from water pipes, the sound should align with running probably hot, or maybe cold water. The sound may lag when you actually run the water by a few minutes since the pipes need to either get hot or get cold before they will expand or contract enough to make a sound.
In my expierience, pipes tend to make a “bang twang” kind of sound. Ductwork makes a hollow sound like tapping a piece of sheet metal. Wood and other similar materials makes more of snapping sound. Experience helps a lot to get an idea what make actually be making any other sound.
I’d also check to see if there is anything loose that may be blowing around in the wind and hitting the wall at times. The other possibility is an animal, like a mouse, getting into a wall or crawl space. Mice tend to jump, and when they land on something (like a duct) after jumping you might here a sound.
It’ll take some investigation to localize the source of the sound. The key is to be methodical, and be observant to try to match up events you see or hear with the sound happening. That will help lead you to the cause.
Bill
Hi Bill,
There is no correlation with anything. We’ve seen it happen in the early evening but often happens between 10pm and 5am. The first night this happened it was very windy (Santa Ana winds were coming through the area) but that only lasts 1 week but the sounds continue. Last night it happened at 11:30pm and again at 4:30am this morning. This doesn’t sound hollow or like a twang but like something banging into wood.
In Cali we have fire sprinklers in the ceiling so that became my latest suspect. To test I moved my cameras into the dining room where the sound comes from with 1 by the wall where we think it is and the other on the ceiling near the sprinkler head. The sound is not coming from the ceiling we found out. Next step is the put the cameras near different locations on the wall to narrow in on the exact spot.
We’re getting closer to the location but the sound doesn’t sound like pipes, vents or rodents but I hope I’m wrong because I’m running out of causes. If anything else comes to mind, I’m all ears.
I’d say it might be woodpeckers, but they’re not usually active at night.
If it’s random, and at night, I’d suspect vermin of some sort. Some kind of nocturnal critter. Look for signs of chewing and other damage on the exterior, especially any concealed or sheltered areas (under eaves, behind bushes, etc). Check all your roof vents. Check in the attic too (but be careful, you don’t know what you might find hiding in there).
Bill
Not sure how there might be a sufficiently large hole in the wall's top plate, but maybe the rodent idea has some merit. They cache seeds and nuts, sometimes in large quantities. Perhaps the randomness of the thumps is related to activity in the pile. If it is resting near a hole for wire, sprinkler pipe or just a misplaced hole, random seeds or nuts might be dropping into the wall and hitting the base plate and perhaps a piece of blocking on the way down. That might account for the one or two knocks. Do you have seed or nut bearing bushes or trees?
If it is a critter, I recommend Reese's Pieces as bait for live trapping. Raccoons like them very much, so I guess chipmunks and squirrels will too.
I like this theory. At first watch it startled me with it being so loud- I was expecting much less.
Hearing it a second time, it does sound like an acorn falling from 10’, although the second knock seems too quick on the rebound.
I had a woodpecker on the metal cap of my chimney- the whole house echo’d like nothing I’d ever heard before.
An acorn would probably fit through an empty hole made to run wire. Those holes are usually 5/8” or 3/4”.
If the acorn fell and hit an electrical box or som blocking, it might make multiple quick knocks.
I know from experience in my own house that if critters are borrowing in your insulation, you’ll probably need to replace it. I’m picking up some mineral wool batts tomorrow to replace mouse damaged fiberglass.
Bill
Food for thought Truss uplift
No very likely given how little difference you have from high to low temp.
https://www.carsondunlop.com/inspection/blog/truss-uplift/
Walt
Usually it’s a double knock but not always the same delay between knocks. And then sometimes it’s a single knock.
I have no trees above my house to drop acorns in either.
Tdjanke, I realize this is an old forum, but did you ever resolve where this sound was coming from? We are hearing same sound on our Wyze cameras?
Thanks.
Jsrtmc,
Back again with a possible alternative to rampant rodents. I have heard trusses pop now that I have them. A combination of moisture and heat differences will make them move just enough on the top sills to make their complaints heard. At least, I hope the join plates are the source.
I should have thought to pose the idea of truss movement before, as I have had to re-screw drywall ceilings that had many of the screws pulled through the drywall by truss members lifting aggressively. I suggest looking for little splits in the corners of wall to ceiling near where you hear the banging if you also have trusses. They can move when the sun goes across a roof and the shadow side cools faster. Metal roofs are also quite "poppy".
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Hello I hope someone can answer your question regarding the knocking because - we live in the Midwest and have the same problem in fact we have called the police they only listened to it with no response as to what it was, we called the fire department - (the fire department thought it was water hammer) they went through every part of my all electric condo - we called 2 different plumbing companies both plumbers said it was not water hammer so that was a 400.00 bill then we called HVAC service man (another 90.00) he turned off the air flow to the house and said it’s not my ducts. My neighbor thinks it’s my kids but usually each time the sound is heard we are all together. We are running out of money and ideas so maybe there is a logical explanation- I have attached a video for the audio any Logical ideas on where to go next will be appreciated - Thank you
That sounds like pipe expansion noise. Water and drain lines expand when they heat up, sometime if not well supported or tight through a stud it makes that sound as it heats up or cools down. Very hard to find and fix as it carries through the structure.
Might be pipe expansion noise. It’s really hard to tell. Pipes generally make noise when they change temperature quickly, usually when you start running the hot water. If the sound seems to be loudest near an exterior wall, I’d suspect the gutters might be the source of the noise.
What you need to do is try to find it where the sound is strongest, then think about what materials in that particular area might be expanding/contracting to cause the sound. Think about pipes, gutters, siding, etc. It’s very unlikely this noise is coming from wiring. Critter noise tends to be more random, so my guess would be thermal expansion (from something warming up) or contraction (from something cooling off). If the sound happens in the morning or evening, it’s probably something on the exterior of your home. If the sound happens when someone uses a sink or shower, that’s probably water pipes. Find the area of the sound first, then take note of what time it happens most frequently, then think about what in that area is going on at that time and you can start to get closer to finding the cause.
Bill
Thanks for the insight we have another appointment for another plumber to come out Monday to test the pressure by turning off the water from the street. But now maybe we will Cancel the plumber appointment and look for a good maintenance man - our HOA should help with this thanks again
Pressure causes water hammer. Water hammer happens when you open or close (usually close) valves like faucets. Water hammer is usually one big BANG or BOOM, not a “tick, tick, tick” sound. The cyclic ticking is usually thermal cycling.
I have sometimes used a one or two sizes too big pipe clamp with a wrap of rubber sheet around the pipe with the clamp over that. This can help damp vibrations. Thin sheets of rigid polyethylene can help on horizontal runs since it acts like a linear bearing.
Another thing that can help quiet down pipes is to rigidly clamp the pipe periodically with the clamp-over-rubber arrangement I described earlier. When doing this, you’ll get the best results if you’re clamps aren’t perfectly evenly spaced. Even spacing can allow resonances. Resonances will be damped if the clamps are all spaced at slightly different intervals. Don’t clamp at halves, either, use odd multiples like 1/3, 3/5, etc. The goal is to maximize the vibration damping.
Bill
gotsameknocking,
Well, back to add a guess. Your sound has a soft start then three major peaks. The lifting truss noise I have heard is more often than not a single bang. Fairly sharp definition, no repeats. The CPVC piping I had in an early home would make a fairly long series of "tik tik tik tik" when drawing hot water. I greased the plastic clips that held the pipe and all went quiet. The big PVC drain that passed through a joist and dragged a bit sounded much the same, only lower pitch. Teflon tape slipped under the contact point fixed that.
The sound you have recorded and presented leads me to guess a partial plugged vent or trap that is being emptied in a cyclic manner, perhaps through suction effect. Are you new to the home or later owner? Any memories of toys or clothing that got sent down the plumbing by accident?
I am basing this guess on two incidents I had with bad plumbing in an old house. The first was an ice cap on my vent stack one winter long ago when the temperatures fell far below zero. The toilets started flushing most oddly with burbles and gulps that confused me. It seemed like a pressure balance issue, so I checked the vent stack and sure enough it was almost totally closed by ice that had formed by freezing the moist vent air from baths and showers meeting sub zero air in a iron pipe. Clearing the pipe cleared the problem. The second was a bathtub with a long horizontal drain with nearly zero pitch ending in a drum trap. Years of hair and goo had reduced the cross section so severely that draining the tub took ages and it would often go "bloop, bloop, bloop" as it drained.
The tests I would suggest, if a one story house, is run sink, toilet, tub in separate cycles to see which one sets off the thumps. It may be several minutes between running water and the sound appearing. If more than one bathroom, start with the one furthest from the vent stack if you can determine where that is. For a two story, check the upstairs sink, then tub, then toilet, waiting several minutes between each fixture.
It is barely possible that a bird or squirrel fell down the vent, but they usually rot fast enough to not make the problem last that long. My guess is you will find a toy or fabric wad stuck in a vertical pipe that holds water back long enough to make the air bubble burst up through the water column and go "bloop, bloop, bloop" like the taped noise. If you have a basement where the long horizontal runs can be felt with your hands, then maybe the long pipes are where the water is stacking up and the vertical vent is just carrying the bloop noise upward. Hope you don't have a slab house.
You didn't say what your weather is, but no place in the US has sub-zero temps at the moment so I'm guessing toys, socks or hair globs. If you have a two story house, the vertical vent line can also be a drain line. I think it is called a wet vent. Others better at plumbing might want to weigh in on how the lines might be installed incorrectly or where to best look for a partial plug.
If you have any sense of the plumbing runs and connection points, try focusing your attention on those areas. If you are really into detective work, a cheap stethoscope might be money well spent.
Maybe try an IR camera or endoscope to determine what is in the walls?
I just discovered this thread, and thought for a moment I had posed the original question. I'm not sure if OP solved the issue. I have the metallic, echo-ey knocking behind the plaster and drywall of my bedroom - far from any pipes or heating. So that would seem to rule out the water hammer, though I'm happy to try. I can hear it inside, but if I stand by the exterior wall on the patio, I can't hear it unless I put a glass to the stucco. It seems to be wind-sensitive for some reason, but not consistently. Today it's breezy, and the noise seems louder than last night when it was much windier. My house is cantilevered from the hillside and does groan and creak a bit. I initially blamed the roofers who put on a new torchdown on my flat roof a few months ago, but they said the roof is "tight." Maybe the noise has always been there and I'm just more sensitive. As for weather, it's a pleasant SoCal sunny winter's day, with none of the extremes found elsewhere. So I don't think it's contraction/expansion. Pretty sure it's not a rodent, unless it's quite rhythmic and too lazy to move about.
P.S. the noise is definitely not as intense as the sound captured in OP's post. We don't have AC either. At a guess, I would say a pipe is involved.
Roof membranes flopping around shouldn't make a metallic banging sound, they'll make more of a "flop flop" sound. Hopefully that makes sense -- even though we have a phonetic alphabet, with letters describing sounds, it's remarkly difficult to explain a sound with words :-)
I would check for any tree branches banging gutters or loose gutter sections, those can make noises in the wind, and maybe with thermal cycling too in extreme cases (although I've not see that myself). Pipe or duct sounds can be carried by the framing, so the actual source of the sound might be a distance away from where you are hearing it.
You can check if it's pipes by running hot or cold water after it's not been run for a while. Pipe banging tends to happen when pipes either heat up or cool off quickly. Thermal-related pipe banging is usually a sort of "snap ... snap ... snap" sound that is periodic in nature, and gradually tapers off once the pipe has warmed up or cooled off all the way.
Water hammer is a different sound, and happens at the time a valve is shut off. Water hammer is usually more a muffled "Bang!", sometimes with a rattle immediately afterwards as the pipe that went "bang!" bounces around for a bit (a second or two).
Bill
Thanks, Bill. I have ruled out the roof, and there are no trees or loose gutters. Pipe or duct sounds carried by the framing could be a good line of investigation. I'm definitely aware of pipe issues as my water heater is 16 years old - and it's the eternal question of should I replace it. We get a rumbling sound connected to my wife's shower usage, not to mine. I wouldn't liken it to a "snap ... snap" - and nor is there a muffled "Bang!" It's simply like a piece of metal or wood striking a pipe, and it's right in the bedroom wall next to where my head lies. Great!
If you have cast iron drains it could be your drain stack or one of the vent lines. Lot of times the vent is run in interior walls, the roofer might have moved it enough during the re-roof that is touching some framing. Check if there is a stack vent on the roof in the area you hear the noise in.
If you find a pipe rubbing on framing (such as the vent stack Akos mentioned), and you can't shift it enough to be clear, you can stick a piece of UHMW polyethylene sheet in between the pipe and whatever it's sliding against. UHMW polyethylene is a sort of linear bearing material, and it's great when you need something to act as a bearing between two things that are sliding against each other. Using a bearing material here is like lubricating the joint, and should eliminate the noise.
Note that you need only a very thin sheet of the material to be effective. I'd probably use 1/32", or whatever was the closest standard size to that. You can even get it as an adhesive tape on rolls. I've used the tape-type UHMW to quiet down drawers that are wood-on-wood instead of real glides. Works great, and makes the drawers a lot easier to operate too.
Bill
Mr. Fussy,
A couple of long shot guesses for things to check. A loose vent screen for a crawl space opening if you have them or the flapper on a vent for bath or kitchen vent fan being sucked out and released by wind. This could account for the variable activity as wind direction would be a factor. A soffit vent with loose screws might do the same.
Possibly a hot water pipe that passes through a joist or wall stud, which of course negates the wind part, though maybe the shower cycle is what is really driving the noise pattern.
I did have one odd wind driven noise in a previous house. The mast pipe for the electrical wire hookup was bolted to the exterior wall of our bedroom. The top retaining clip was oversized for unknown reasons, so when the wind blew hard enough to make the service wires wiggle the sound of the mast pipe moving about in the bracket would transfer via the stud it was screwed into the bedroom. I remember it being more of a creaking and thumping sound.
If you have a Casper mattress, it may just be ghosts.
I know it's a old post but just curious...did you find out what that sound was. We are hearing similar sound in our wyze camera as well.
Hello, hoping this post is still active. We have a thump that occurs always in the same location on house wall. It is significantly loud. No pipes on that side of house, definitely temperature driven I feel as it typically happens only in the early morning. We did have a wall ( non load bearing ) removed about 7 years ago. Could it be a truss issue that you here in a wall. We are worried and frustrated we don’t know where to start. Sorry to piggy back the post. Please help. We are in BC Canada
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Hello, we noticed it the last 4/5 mos it is the dark side of the home. It is quite the thump like done threw a ball at the house.
If it is an exterior wall sounds like it may be temperature driven, an expansion of siding or the like. Sunny side of the house or dark side. Summer only or year-round?
Penster,
I agree that temperature is likely driving expansion of something that pops. You mention a wall was removed 7 yrs ago, has the sound been with you since that time? You need to clarify the type of siding and sun exposure levels. Also, does the pitch of the roof face morning sunlight? If it is an east facing wall or roof, the morning sun load could drive enough warmth in fast enough to make the sheathing expand. If just the wall is catching sun, siding noises tend to be lots of little snaps and pops if aluminum. Vinyl is similar but duller in pitch. A single pop is not too likely unless there is just one piece snagging on a trim edge.
A single large thump once a day suggests a truss end(s) at the top plate. It could be the roof sheathing was set dead tight on a cold day when constructed. The sun hitting the roof could warm the plywood enough to make it snap into a curve to relieve the expansion stress. Not much of a curve, but enough to "pop". The truss(es) might be shifting slightly with the plywood and amplifying the sound thanks to the ceiling drywall. Having removed an interior wall may have expanded the drywall area subject to shifting which enhanced the effect.
A long shot suggestion would be the wall sheathing driving the same effect. I have only heard it once in an unfinished tall wall in a great room. And that was more a mass creaking than a thump. Hopefully, the addition of siding and drywall firmed up wall enough to not creak in the sunlight.
Hello, we only started hearing it about 5 mos ago. We have aluminum siding and it is the dark
Side of the house in morning and sunny side at night. I will run this past a friend who has quite a bit of construction and see if he can check out some of your theories. I very much appreciate you taking they one to provide all the information you have. Thank you.
Penster,
Well, the dark side in the morning with a baseball. Sounds like a new game, "Clue for Builders". Based on your update, my suggestions may well be off base. Possibly still related to some distortion of the roof trusses if that is what you have. A long shot, but perhaps the one or more trusses are not firmly tied to the top plates on the sunny side and the movement is transferred across to the shade side. Hard to believe that a base ball size thump would result though.
Trusses and traditional framing can move more than might be expected. More typically due to humidity changes and slowly not suddenly. I have encountered one situation where the seasonal truss movement from humidity shifts caused a ceiling to fail. The up and down bowing of the bottom chord elements pulled the screws through the drywall in major areas until the weight of the cellulose insulation collapsed the drywall. Fortunately, no one was under it when it went.
There are methods for attaching drywall to the bottom chords of trusses that prevent cracking at wall junctions, so truss movement should be familiar to your friend. Hope he is able to diagnose the thump. Like I noted, truss expansion is a slow-ish process and the thump part is a stumper. If it is a one time event each morning, then the trick will be figuring out what is "resetting" over night.
Another thought: Are you missing some ordinary daily activity you do each morning that might be setting off the thump? I have one floor joist that seems to have gotten short glue when the decking went down and now each evening it will "pop" when I go to bed. Just once, it won't repeat until the next evening. It may be that what sounds like the wall is actually a joist end sending the noise up. Check the joist orientation and see if the ends line up under the noisey wall. Perhaps you are far enough north to be using some heat in the morning and a joist that runs parallel to the heating duct gets warmed up just enough to pop once then cools down over night if you are setting back the heat. I will be interested to see what your friend comes up with for ideas as well.
No one knows it in this world except me trust me.This sounds are made by invisible creatures,they will not harm us if we don't try to harm them.In my cases I have seen so many houses particular wall even one flat 55th floor only one wall was making knock sounds.This is somewhat creepy but we cannot visit you.Let them live,Dont worry they will go after years watching you not leaving that home.
Would this be a good time to re-insert my joke about Casper mattresses?
Hi- We have the exact same sound as the original poster. (Tdjenke) However we live in a two story highrise condo in Hawaii and the noise happens exactly 12 hours apart (1:28am and 1:28pm, give or take a minute depending on how quickly I can check the time.) Sound sometimes repeats within a half-hour exactly! Haven’t determined if I can hear it outside yet. Will provide audio as I know when to catch it.
1) Sound comes from one cement interior wall shared by neighbor unit.
2) Sound can be heard upstairs and downstairs on same wall towards one corner of the room closest to outside.
3) Wall is a firewall with area of separation
4) our unit is first unit above garage pedestal
(Sound unlikely coming from below our unit)
We will be consulting w/blding facility manager to find out what’s behind the walls.
Entire building has had hot water and water pressure problems over the last two years.
If this sparks anymore discussion about the source, of this type of sound, Im all ears.
—Albrunner
I was just googling what could cause a banging noise in an interior wall and came across this thread - has anyone figured it out? I've noticed a single bang noise - periodically in an interior wall of my home - I don't know if it's always been there (the home is almost 4 years old), because I rarely use the room it's in, however, I've moved my office into this space and now I hear it daily. I've had an engineer friend over who suggested plumbing vents, etc., however, when I turn off all the a/c in the house and no fans - the noise still occurs. There are no plumbing pipes in the walls - I'm in Florida. It's random - a single very loud bang - I had an inspector go up in the attic and didn't see evidence of a critter nor any kind of vents in the area on the exterior of the home. I'm about ready to burn some sage. I've included a recording of my noise. I called the builder but they said get an engineer - I called an engineer and he said I need a 'forensic' engineer and gave me a name, however, I've left 3 messages and no return call. I'm at a loss.
I hear a bang and a twang, which makes me think there is some spring action in play (which doesn’t necessarily mean an actual spring involved). Being in Florida, I’m thinking you might have a hurricane tie somewhere that is slipping under a fastener a bit with temperature changes. Much force can be generate by thermal expansion and contraction of materials, easily causing things to give like this. Unfortunately, locating exactly where the offending thing is can be difficult since the sound will carry through the structure making it very hard to reliably pinpoint the exact location where the sound originated from.
Bill
I have a noise and was wondering if Bill or someone could diagnosis it. Thanks in advance.
I recommend you start a new thread for your new noise.
Bill