A house shaking at night is usually caused by something that runs during the day too: trucks, trains, a furnace, a pump, or a neighbor’s washer. You just notice it more when the house is quiet and you’re lying still. To find the cause, you need a record of when it happens, how strong it is, and how fast it shakes. The house vibration logger keeps that record with your phone. Leave it on the floor overnight and check the timeline in the morning.
Why you feel it more at night
Three things make night shaking stand out.
- It’s quiet. During the day, noise and your own movement cover small vibrations. At night nothing covers them.
- You’re lying still. Your body rests on the bed and you’re paying attention, so you pick up tiny movements. Caltrans (2020) puts the point where continuous vibration becomes barely perceptible at a peak velocity of just 0.01 in/s (0.25 mm/s).
- Some sources run at night. Freight trains, deliveries and road work often happen late at night or early in the morning.
A bed frame and a wood floor can also amplify a small shake, so it can feel stronger upstairs than it is at the foundation.
Common causes of a house shaking at night
Heavy trucks and buses
A truck or bus hitting a pothole, a speed bump or a raised manhole cover sends a jolt through the ground. Each event is short, a few seconds, and they come at random times. They are worse where the road surface is rough and on houses close to the road. The traffic and train vibration test is set up for exactly this.
Trains
A passing train shakes the ground for longer, often a minute or more. Freight trains often run at night, and events tend to repeat at similar times each night.
Equipment in your own house
Furnace and AC blowers, heat pumps, water heaters, well pumps, sump pumps and refrigerators switch on and off through the night. A loose duct, a pump bolted to a floor joist, or an outdoor unit on a sunken pad can pass that shake into the frame. The pattern is regular: on for a while, off for a while, about the same strength each time.
To test, switch things off one at a time and see whether the events stop. You can check single units with the AC unit vibration test or the refrigerator vibration test. Fixed-speed fridge compressors run at about 3,000 to 3,600 RPM (50 to 60 Hz), faster than a phone can measure, so the frequency shown for them may be wrong.
Neighbors
In apartments, townhouses and duplexes, a neighbor’s washer on spin, a subwoofer, a treadmill or heavy footsteps can travel through shared floors and walls. Late laundry and home workouts are common culprits. The subwoofer vibration test and the treadmill vibration test help you check those.
Wind
Gusty wind can rock a house, especially the upper floor of a wood-frame house or a house on an exposed hill. These events line up with the weather, not the clock.
Nearby work or industry
Night road work, rail maintenance, and plants with big fans or compressors can shake houses nearby. If there is construction next door, use the construction vibration monitor. Its report is made for that situation.
Earthquakes
In active areas, small earthquakes can wake people up. If you felt a single sharp jolt, check the USGS latest earthquakes map. Our online seismometer shows a live trace, but it is not an earthquake warning system.
Things that feel like shaking but aren’t
Low-frequency sound, like a distant engine hum or heavy bass, can rattle windows and feel like shaking even when the floor barely moves. A phone on the floor measures the floor, not sound in the air. If you often feel motion and nothing ever shows up in the log, mention it to your doctor too. Inner-ear problems can feel like movement.
How to log it overnight
- Pick the room where you feel it most. Place your phone flat on a hard floor, screen up, away from where people walk. Don’t put it on the bed or on a thick rug.
- Plug in the charger. The screen stays on while logging, so turn the brightness down. Leave the page open.
- Tap “Start logging.” The default threshold is Noticeable. If the log fills up with small events, raise it to Strong.
- When you feel shaking, write down the time on paper. Don’t touch the phone.
- In the morning, open the timeline. Each event shows the time, the peak velocity in mm/s, the frequency in Hz, and how long it lasted.
- Log for a few nights. One night can mislead you. A pattern over several nights won’t.
Tips for a cleaner log
- Mind the footsteps. Anyone walking near the phone, including pets, shows up as an event. Note when you went to bed and got up so you can ignore those.
- Pick the spot for your question. To know what you feel in bed, log in the bedroom. To know what reaches the house from outside, log on the ground floor near the wall that faces the road or tracks.
- Rule out your own equipment. Run the dishwasher and laundry earlier in the evening. If you suspect the furnace or a pump, log one night with it on and, if that’s safe and comfortable, one night with it off.
Everything stays in your browser. You can download the log as a CSV file or a PDF report, and clear it with “Delete all logs.”
Reading the pattern
| What the log shows | Likely source |
|---|---|
| Short events of a few seconds at random times | Trucks and buses |
| Longer events, a minute or more, at similar times | Trains |
| Regular on-off events of similar strength | Your furnace, AC, pumps or fridge |
| A steady shake all night at one frequency | A machine running nonstop, yours or nearby |
| Events that follow gusty weather | Wind |
| One sharp event that neighbors felt too | Possibly an earthquake |
| Nothing logged when you felt it | Sound, very small movement, or a source faster than about 30 Hz |
The frequency helps too. A machine shakes at the same frequency every time. Traffic events vary from one to the next. For more on reading Hz, see vibration frequency explained.
How strong is too strong?
The logger uses the Caltrans (2020) human response levels for continuous vibration, based on peak velocity:
| Label | Peak velocity |
|---|---|
| Barely noticeable | under 0.25 mm/s (0.01 in/s) |
| Noticeable | 0.25 to 1.0 mm/s (0.01 to 0.04 in/s) |
| Strong | 1.0 to 2.5 mm/s (0.04 to 0.1 in/s) |
| Very strong | over 2.5 mm/s (0.1 in/s) |
Annoying is not the same as damaging. For continuous vibration, Caltrans gives a damage guideline of 0.3 in/s (7.6 mm/s) for older homes and 0.5 in/s (12.7 mm/s) for new ones. That is three to five times the level where Very strong begins. So vibration strong enough to keep you awake is usually well below the level that cracks walls. The construction vibration limits page has the full tables.
What to do with what you find
- Your own equipment: tighten mounts, add rubber isolation pads, level an outdoor unit’s pad, or have the system serviced.
- Neighbors: show them the log and the times. Moving a washer away from a shared wall, or putting a treadmill on a thick mat, often solves it.
- Traffic: report potholes, bumps or loose manhole covers near your house to your city or state road department. Fixing one bad spot can remove the worst events.
- Trains or industry: share the report with the operator and your local officials.
- Cracks or damage worries: talk to a structural engineer. For a dispute, hire a professional vibration monitoring company. Our guide on whether construction vibration can damage your house explains the limits.
The phone log is for your own records and to start a conversation. It is a good guide, not a certified measurement. Start tonight with the house vibration logger.