Mystery Intermittent Noise in New House
A friend recently built her 900sf home in New Mexico, zone 5b. It is 2×6 frame, blown in cellulose walls and attic, concrete slab with 32″ foundation. She called a few days ago and told me about an intermittent hum that sounded mechanical, (like a pump) but she couldn’t locate the point of origin. Her mechanical contractor (very competent) couldn’t find anything. My advice was to turn off the main breaker when the noise was happening to see if that would stop it, and then turn on one breaker at a time to isolate the circuit, and then do the unplugs, one at a time, to pinpoint. But the noise continued when the power to the house was shut off. She has radiant heat (open loop) powered with by a propane powered Navien boiler and a pellet stove. Her water line is from city water, run in plastic and her takeoff is about 200 feet away and the run from there to her house is pex. She is on grid, and power lines are run underground. Her septic is a split system, gravity fed. The noise seems to come mostly in the morning or at night – not so much in the afternoon. Does anyone have an idea as to where this sound is coming from or how to trouble shoot it? I am wondering now if it is a hum or vibration from source external to the house that is being transmitted through conduit or pipe.
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Try getting a recording of the sound. Other people’s descriptions of sounds do not often compare well to mine.
The morning and night part make me think it is thermal something expands when it gets warm in the morning and contracts again at night. Does it happen more on days when it is or was sunny? Vinyl siding does move a lot and can make some noise if you are close by and outdoors.
You may want Google” truss uplift sounds”
Walta
Taos Hum?
I agree with Walter in that it might be due to thermal expansion of some kind. Vinyl siding/trim or a metal roof would be good candidates, especially if they are dark colored.
For what it is worth, I had a similar situation in my new home. For two years, we would hear this deep thumping sound coming from the ground near our home. You could feel it as much as you could hear it. It sounded like an earthquake was imminent or that a sink hole was about to open up. But the sound would only happen in the Spring.
Then one day as I was working from home I saw a strange bird walk by through the window and decided to google it. Within minutes, I had figured out what that haunting noise was!
As part of their spring time mating ritual, Grouse find a hollow log and flap their wings so quickly that they create tiny sonic booms. The sonic booms combined with the acoustics of the hollow log are responsible for the deep, center-of-the-earth type thumps.
So- don't rule out mother nature as well!
PS: Here is the video that solved the mystery. The video doesn't do the noise justice. It is a DEEP, DEEP base sound:
https://youtu.be/wmMLb4_f8L0
Thermal expansion is usually a stick/slip/stick/slip type of motion, which makes a sound like "tick, tick, tick" or "thump, thump, thump". The important part is that the sound will usually be of a repetitive, periodic nature. If that's what you're hearing, I'd suspect thermal expansion/contraction if the sound happens when the sun comes up and contraction when the sun goes down, and that could be siding, roofing, or trusses as others have mentioned.
If the sound is a fairly continuos "hummmmmmm" over a periodic of more than a few seconds, I'd suspect some kind of mechanical (or electrical) system. Since you already did the "one breaker at a time" test (good thinking on that, BTW), all that is left is your propane powered boiler. I'm not very familiar with your unit, but I'd check the flue gas flow for possible sound and any circulating water sounds. Sometimes sounds from things like that can carry through the structure which makes it harder to pinpoint the source.
If you find the sound is coming from piping of some kind, the solution is often to add some NON-evenly spaced clamps, ideally connected to a very rigid part of the structure (like a concrete wall). You want to space them somewhat randomly and at odd intervals (like 1/3 or 2/7) to maximize damping of any resonances in the piping. I did exactly that to quiet down my water well pipe which otherwise coupled a fair bit of sound into the floor joists which I thought was annoying. I made some rigid clamps out of 2x4 chunks, attached them to the block wall in the basement, then used 2-hole conduit straps with a piece of 1/8" neoprene sheet wrapped around the pipe under the clamp. There is MUCH less conducted sound now.
Bill