Mysterious Banging/Thumping Noise from Walls – Any Ideas?

Hello all, i am a new homeowner in california. I’ve been hearing a strange banging or thumping noise coming from within the walls of my house, and I’m hoping someone here can help me figure out what might be causing it. The sound happens randomly during the day, mostly when it’s warm outside, and lasts for about 20-30 seconds in a continuous pattern. What’s puzzling is that it happens when neither the AC nor the heater is running. There’s no whole-house fan, and all the bathroom exhaust fans are humidity sensor-operated. I initially thought that maybe a few fans were turning on and off automatically, causing something to rattle, so I disconnected the humidity sensors and manually turned multiple fans on and off, but I couldn’t recreate the noise. I’ve also had the roof inspected, and everything checked out fine. I even looked at the exterior dampers and added some insulation to rule them out, but the sound persists. I recorded the noise here: https://jmp.sh/ljeXYqFX. Does anyone have any ideas on what HVAC components could be responsible for this? submitted by /u/Inside-Hat-8065 [link] [comments]

Mar 19, 2025 - 19:12

Hello all,

i am a new homeowner in california. I’ve been hearing a strange banging or thumping noise coming from within the walls of my house, and I’m hoping someone here can help me figure out what might be causing it. The sound happens randomly during the day, mostly when it’s warm outside, and lasts for about 20-30 seconds in a continuous pattern. What’s puzzling is that it happens when neither the AC nor the heater is running.

There’s no whole-house fan, and all the bathroom exhaust fans are humidity sensor-operated. I initially thought that maybe a few fans were turning on and off automatically, causing something to rattle, so I disconnected the humidity sensors and manually turned multiple fans on and off, but I couldn’t recreate the noise. I’ve also had the roof inspected, and everything checked out fine. I even looked at the exterior dampers and added some insulation to rule them out, but the sound persists.

I recorded the noise here: https://jmp.sh/ljeXYqFX.

Does anyone have any ideas on what HVAC components could be responsible for this?

submitted by /u/Inside-Hat-8065
[link] [comments]