Smart Home Fix

How to get a phone alert when the washing's done, without an electrician

Last reviewed: 21 July 2026

The washing machine finishes downstairs, you don't hear it, and the load sits wet in the drum until you remember it that evening. Classic. There are smart plugs that watch power draw, but they mean fiddling with the machine's power, they don't like big motors, and if the laundry is out in the garage or a granny flat there's often no decent WiFi out there anyway. There's a simpler way to get a phone alert when the washing's done that needs no electrical work at all: listen for the vibration, not the power.

Why vibration beats power monitoring

A washer or dryer shakes when it runs. A cheap vibration sensor stuck to the machine can feel that, and it tells you the one thing you actually care about, did a cycle start, without ever going near the mains.

The advantages stack up:

You don't need to measure the whole cycle. You just need to catch the start, then let your home hub run a timer.

The trick that stops false alarms

The catch with a vibration sensor is that everything vibrates it, a door slam, someone bumping the machine, a truck going past. If you fire an alert on the first shake, you'll get nonsense.

The fix is a short confirm window. Instead of "one shake means running", the rule is: see several shakes within about ten seconds, then call it running. A door slam is one thump and gone. A spin cycle is continuous. That one rule kills almost all the false triggers.

Then you latch it, once it's decided the machine is running, it sends a single "started" message and stops chattering. It doesn't need to keep reporting; the hub takes it from there.

Let the timer live in your hub, not the sensor

Here's the part people get wrong: they try to make the sensor smart enough to know when the cycle ends. Don't. Sensing the end is fiddly and machine-specific.

Instead, keep the sensor dumb and put the brains in your home hub (Home Assistant, or similar):

  1. Sensor detects the start, sends one "started" message.
  2. Hub flips a "washing running" switch on and starts a timer, say 45 minutes for your usual wash.
  3. Timer ends, hub sends the "washing's done" notification to your phone.

The big win: you can change the timer to match your machine's real cycle length without touching the sensor, no reflashing, no getting the battery back out. Different timer for the dryer, a longer one for towels. It's all in the hub.

What you need

Mounting matters more than the part. Stick the sensor rigidly to bare metal, the top or rear panel of the machine, not onto rubber feet or a soft, damped panel that soaks up the vibration. Get the mounting right and even a cheap sensor is reliable.

Start with one machine

Prove it on the washer first, it's the harder machine and the one that matters most. Watch one real wash cycle, tune the number of shakes it takes to trigger, then add the dryer once you trust it. One sensor, one machine, one timer, get that working end to end before you expand.

The short version

You don't need to rewire anything to get a "washing's done" ping. A vibration sensor catches the start, a short confirm window filters out the bumps, and your home hub runs the timer and sends the alert. Cheap, battery-powered, and it works even when the laundry is out of WiFi range.

This is a how-to based on how we build these sensor nodes; parts named are examples, not the only option.

Want an alert like this built and wired into your smart home, without touching the mains? That's the kind of build we do. No lock-in, no upsell to gear you don't need. Tell us what you want to automate and we'll sort it.